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Publication Series - NCHRP Research Results Digest
Preliminary reports to provide early awareness of research results emanating from Cooperative Research Program projects.
Items found: 290
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329 - Highway Safety Manual Data Needs Guide
6/16/2008
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 329: Highway Safety Manual Data Needs Guide is designed to help potential users of the 1st edition of the Highway Safety Manual (HSM) anticipate the data needs for using the HSM. The guide focuses on the data needed to use the HSM Part C methodologies for rural two-lane highways, rural multilane highways, and urban and suburban arterials. The guide provides information designed to help potential HSM users assess whether their existing data sources contain the data needed to apply the HSM safety prediction methodologies to highways of interest. [More] | |
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328 - Color Effectiveness of Yellow Pavement Marking Materials: Summary
6/2/2008
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digestion 328: Color Effectiveness of Yellow Pavement Marking Materials explores range of chromaticity coordinates that observers classify as yellow and white under daytime and incandescent illumination. The full report of the project described by NCHRP Research Results Digest 328 was produced as NCHRP Web-Only Document 125. [More] | |
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327 - Transportation Implications of Emerging Economic Development Trends
9/1/2008
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 327: Transportation Implications of Emerging Economic Development Trends explores economic development trends and how transportation relates to these trends. The report focuses on business production, inventory, and logistics and distribution trends and practices; site selection research and practices; labor market considerations; urban and rural development practices; and international trade and global market trends and implications. [More] | |
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326 - State Public Transportation Division Involvement in State Emergency Planning, Response, and Recovery
5/15/2008
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 326: State Public Transportation Division Involvement in State Emergency Planning, Response, and Recovery explores the best policies and practices of state transit divisions pertaining to weather-related emergencies. The report highlights lessons learned from recent emergencies, issues associated with the involvement of state public transportation divisions, and best practices. [More] | |
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325 - Continuing Project to Synthesize Information on Highway Problems
1/17/2008
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 325: Continuing Project to Synthesize Information on Highway Problems is a digest of the progress and status of NCHRP Project 20-5, “Synthesis of Information Related to Highway Problems.” [More] | |
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322 - Public Information and Education in the Promotion of Highway Safety
11/9/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 322: Public Information and Education in the Promotion of Highway Safety assesses the role of public information and education programs in contributing to behavior change in the highway safety area. [More] | |
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320 - Current State Issues with Implementing Federal Transit Administration (FTA) Section 5310 and Section 5311 Programs
7/20/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 320: Current State Issues with Implementing Federal Transit Administration (FTA) Section 5310 and Section 5311 Programs examines current issues facing state departments of transportation in the management and administration of their Elderly Individuals and Individuals with Disabilities program (Section 5310) and the Nonurbanized Area Formula program (Section 5311). The report also explores options for addressing these issues. [More] | |
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319 - Buy America Issues Associated with the State DOT Procurement of Paratransit Vehicles Using FTA Funds
7/12/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 319: Buy America Issues Associated with the State DOT Procurement of Paratransit Vehicles Using FTA Funds examines the Buy America requirements applicable to state departments of transportation (DOTs) and their sub-recipients in purchases of paratransit vehicles and examines opportunities for change. The report is primarily focused on rural and small urban areas; however, Buy America regulations apply equally to all motor vehicles purchased with U.S. Federal Transit Administration grant funds, regardless of the program through which the grant was awarded. [More] | |
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318 - An Expert System for Recommending Speed Limits in Speed Zones
6/7/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 318: An Expert System for Recommending Speed Limits in Speed Zones explores the development of a knowledge-based expert system decision-support tool to help identify speed limits in speed zones on highways and local roads that are considered credible and enforceable. The decision-support tool software may be downloaded as an .ISO image. [More] | |
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317 - Prototype Software for an Environmental Information Management and Decision Support System
4/25/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 317: Prototype Software for an Environmental Information Management and Decision Support System explores an effort to design, test, and demonstrate a prototype software program for an environmental information management system (EIMS) that state departments of transportation and others could use to support their environmental decision making throughout the transportation system management process. The EIMS is intended to serve as one component of an agency’s broader environmental management system (EMS). The project resulted in prototype software designed to support environmental management for transportation and planning agencies. The final report, including a user’s guide, is available as NCHRP Web-Only Document 103. [More] | |
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316 - Using Surface Energy Measurements to Select Materials for Asphalt Pavements
5/10/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 316: Using Surface Energy Measurements to Select Materials for Asphalt Pavements summarizes an investigation of the effectiveness and practicality of surface energy measurement as a tool for routine screening and selection of materials for optimum performance of hot-mix asphalt pavements. The summary also includes information on three proposed test methods for determining surface energy. The complete final report of the investigation has been published as NCHRP Web-Only Document 104. [More] | |
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315 - Centralized versus Decentralized State Procurement of Paratransit Vehicles for the Federal Section 5310 Program
6/15/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 315: Centralized versus Decentralized State Procurement of Paratransit Vehicles for the Federal Section 5310 Program examines the procurement experience of states that directly and indirectly procure paratransit vehicles applying funds from the federal Elderly Persons and Persons with Disabilities Program (49 U.S.C § 5310). The report is designed to help states improve their current procurement processes or enable them to strategically consider alternative processes for acquiring vehicles for this program. [More] | |
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314 - State DOT Staff Resources for Administering Federal Public Transportation Programs
5/3/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 314: State DOT Staff Resources for Administering Federal Public Transportation Programs examines the staff resources that state departments of transportation (DOTs) devote to public transportation programs and explores the ability of the states to adequately administer existing and emerging Federal Transit Administration public transportation programs. Appendices A through E to the report were published as NCHRP Web-Only Document 99. [More] | |
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313 - Cost-Allocation Methods for Commuter, Intercity, and Freight Rail Operations on Shared-Use Rail Systems and Corridors
3/29/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 313: Cost-Allocation Methods for Commuter, Intercity, and Freight Rail Operations on Shared-Use Rail Systems and Corridors explores issues associated with the initiation of commuter rail or intercity passenger rail service within a shared-use corridor. The report examines current commuter and intercity passenger shared-use rail arrangements; highlights both the allocation of operating and maintenance costs and the arrangements for making infrastructure improvements; and identifies the cost allocation methodologies, capital investment strategies, and other associated issues. In addition, the report investigates opportunities for potential outreach and buy-in efforts among system stakeholders and identifies potential future research needs. [More] | |
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311 - FMCSA Regulations as They Apply to FTA Section 5310/5311 Providers: A Handbook
2/28/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 311, FMCSA regulations as they Apply to FTA Section 5310/5311 Providers: A Handbook is designed to help state and local governments, transit agencies, and others who provide transportation services supported by U.S. Federal Transit Administration Section 5310 and 5311 grants identify the Federal Motor Carrier Safety Administration (FMCSA) regulations associated with these programs and address those regulations cost effectively. Section 5310 grants provide local operators with funding for public transportation for those who are elderly or have disabilities. Section 5311 grants provide funding to transit providers in rural areas. [More] | |
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309 - Continuing Project to Synthesize Information on Highway Problems
2/15/2007
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 309: Continuing Project to Synthesize Information on Highway Problems is a digest of the progress and status of NCHRP Project 20-5, “Synthesis of Information Related to Highway Problems.” [More] | |
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308 - Changes to the Mechanistic Empirical Pavement Design Guide Software Through Version 0.900, July 2006
12/5/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 308: Changes to the Mechanistic Empirical Pavement Design Guide Software Through Version 0.900, July 2006, summarizes numerous changes made to the original Version 0.7 of the Mechanistic-Empirical Pavement Design Guide (MEPDG) software. Specifically, the digest describes the corrections incorporated in Version 0.8 (released in November 2005) and the mainly technical improvements and enhancements included in Version 0.900 (released in July 2006). [More] | |
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307 - Independent Review of the Mechanistic Empirical Pavement Design Guide and Software
12/15/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 307: Independent Review of the Mechanistic Empirical Pavement Design Guide (MEPDG) and Software explores the findings, conclusions, and recommendations of the independent review of new hot-mix asphalt pavement design, new Portland cement concrete pavement design, composite pavement design, and design reliability. The Digest also examines corrections and improvements to the MEPDG software, which represents the day-to-day implementation of the design guide itself. [More] | |
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306 - Identification of Liability-Related Impediments to Sharing ยง409 Safety Data among Transportation Agencies and a Synthesis of Best Practices
11/21/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 306: Identification of Liability-Related Impediments to Sharing §409 Safety Data among Transportation Agencies and a Synthesis of Best Practices examines liability risks associated with sharing safety data among transportation agencies pursuant to Section 409 of Title 23, U.S.C. The report also explores best practices; reviews the Pierce County, Washington v. Guillen decision and its potential impact on managing state liability risk; and describes potential strategies for overcoming the impediments to data sharing, specifically those related to liability. The appendixes to NCHRP Research Results Digest 306 was published as NCHRP Web-Only Document 89. [More] | |
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303 - Safety Impacts and Other Implications of Raised Speed Limits on High-Speed Roads
5/24/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 303: Safety Impacts and Other Implications of Raised Speed Limits on High-Speed Roads explores the effects of raised speed limits from 55 miles per hour or greater on freeways and non-freeways in rural and urban settings. The effects considered included impacts on safety and operations, as well as socioeconomic and environmental effects. The full report is available on the TRB website as NCHRP Web-Only Document 90. [More] | |
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302 - Core Competencies for Highway Safety Professionals
8/3/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 302 examines to what extent core competencies for highway safety professionals are incorporated into existing safety curricula and suggests strategies to expand their application to a broader audience. [More] | |
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301 - Continuing Project to Synthesize Information on Highway Problems
1/12/2006
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 301: Continuing Project to Synthesize Information on Highway Problems outlines the NCHRP synthesis research process, and provides a list of ongoing and completed NCHRP synthesis reports. [More] | |
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300 - Outcomes of the Environmental Streamlining Pilot Projects
12/14/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 300: Outcomes of the Environmental Streamlining Pilot Projects describes the analysis of 10 environmental streamlining projects and suggests a “toolbox” of best practices for reducing the time associated with highway-project environmental reviews and approvals. The digest discusses the main points presented in the final report for NCHRP Project 25-24, “Monitoring, Analyzing, and Reporting on the Environmental Streamlining Pilot Projects,” published as NCHRP Web-Only Document 79. [More] | |
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298 - Use of Event Data Recorder (EDR) Technology for Highway Crash Data Analysis
8/25/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 298: Use of Event Data Recorder (EDR) Technology for Highway Crash Data Analysis examines the benefits and the costs of using EDR data in highway crash data analysis and research. The report also summarizes the final report of NCHRP Project 17-24 that is available as NCHRP Web-Only Document 75. Web-Only Document 75 examines recommendations for the enhancement of EDRs to meet the specific needs of highway crash data analysis and includes recommended EDR database format for agencies that seek to collect and systematically store EDR data. [More] | |
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297 - New Facility for Calibrating Retroreflectometers
6/22/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 297: New Facility for Calibrating Retroreflectometers announces the results of NCHRP Project 05-16 (National Calibration Facility for Retroreflective Traffic Control Materials), which developed dedicated reference instrumentation to provide national calibration standards for retroreflectivity, thereby improving the accuracy of measurements made by other instruments. [More] | |
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296 - Comprehensive Human Factors Guidelines for Road Systems (Research Results Digest)
5/31/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 296: Comprehensive Human Factors Guidelines (HFG) for Road Systems summarizes NCHRP Web Document 70 of the same title that examines the recommended content, format, organization, and capabilities of the planned HFG. Web Document 70 includes an outline of the HFG and a detailed work plan for development of the first edition of the guidelines. The web document also includes a draft Introduction and one sample chapter of the HFG. The HFG is being developed to help facilitate safe roadway design and operational decisions. [More] | |
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295 - Availability and Accessibility of Liability and Excess Insurance for Public Transit and Private Coach Operators
4/18/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 295: Availability and Accessibility of Liability and Excess Insurance for Public Transit and Private Coach Operators examines alternatives to conventional liability insurance coverage for public transit agencies and private motorcoach (coach) operators in response to the insurance crisis of the early 2000s, which has had, and continues to have, a significant impact on the cost and availability of liability insurance coverage. [More] | |
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294 - Transit-Oriented Development: Developing a Strategy to Measure Success
5/6/2005
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 294: Transit-Oriented Development: Developing a Strategy to Measure Success identifies and evaluates various indicators of the impacts of transit-oriented development, provides the results of a survey of transit-oriented development indicators, and identifies ten indicators that may be used to systematically monitor and measure the impacts of transit-oriented development. [More] | |
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292 - Continuing Project to Synthesize Information on Highway Problems
11/9/2004
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 292: Continuing Project to Synthesize Information on Highway Problems outlines the NCHRP synthesis research process, and provides a list of ongoing and completed NCHRP synthesis reports. [More] | |
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270 - Studying Portland Cement Characteristics and Durability
10/31/2002
TRB's National Cooperative Highway Research Program (NCHRP) Research Results Digest Number 270: Relationship of Portland Cement Characteristics to Concrete Durability examines the effects of cement characteristics on certain aspects of concrete durability and recommends changes to cement specifications. [More] | |
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267 - Utility of Translation Software
6/17/2002
An assessment of the state of the art of software for translating foreign-language documents into English is offered in TRB's NCHRP Research Results Digest 267: Utility of Machine Translation Software. [More] | |
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266 - Asset Management Guidance for Transportation Agencies
4/29/2002
Descriptions of three reports on synthesis, framework, and recommended research on asset management for transportation agencies are included in the National Cooperative Highway Research Program (NCHRP) Research Results Digest 266: Asset Management Guidance for Transportation Agencies. [More] | |
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265 - AASHTO Strategic Highway Safety Plan--Case Studies
4/29/2002
Findings of five case studies documenting the use of the AASHTO Strategic Highway Safety Plan in developing state strategic safety plans are documented in the National Cooperative Highway Research Program (NCHRP) Research Results Digest--Number 265: AASHTO Strategic Highway Safety Plan--Case Studies. [More] | |
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264 - LTTP Data Analysis: Factors Affecting Pavement Smoothness
2/7/2002
TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 264: LTTP Data Analysis: Factors Affecting Pavement Smoothness highlights the factors affecting pavement smoothness, identified in National Cooperative Highway Research Program (NCHRP) Project 20-50(08/13), on the basis of the data available from the Long-Term Pavement Performance (LTPP) studies. The research, completed in August 2001, provided preliminary conclusions regarding the factors affecting pavement smoothness of different types of new and rehabilitated pavement structures. Data related to pavement structure and features, rehabilitation techniques, climatic conditions, traffic levels, layer materials and properties, pavement distress variables, and other factors that may contribute to changes in pavement were extracted from the LTPP data tables and compiled in a project-specific database to facilitate the analysis. The International Roughness Index (IRI) was adopted as the measure of pavement smoothness. This digest provides a summary of the work performed in this research. [More] | |
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263 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
9/4/2002
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it is from research and much from the work of practitioners faced with problems in their day-to-day work. There has been no systematic means for assembling and evaluating such useful information and making it available to the entire highway community. The American Association of State Highway and Transportation Officials has, therefore, through the mechanism of the National Cooperative Highway Research Program (NCHRP), authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study searches out and synthesizes useful knowledge from all possible sources and prepares documented reports on specific topics. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice. Each report is a concise document pertaining to a specific highway topic. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 2002 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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262 - Field Shear Test for Hot Mix Asphalt
2/1/2002
This digest summarizes key results of National Cooperative Highway Research Program (NCHRP) Project 9-18, "Field Shear Test for Hot Mix Asphalt." Of particular interest is the description of the redesign of the field shear test (FST) device which was developed as a potential quality control and quality assurance (QC/QA) tool. The redesigned FST was found capable of performing a variety of tests, but the best results were obtained from the frequency sweep procedure described in American Association of State Highway and Transportation Officials (AASHTO) TP7 at high temperatures and high frequencies. Under these conditions, the equipment produced dynamic modulus values and phase angles in the same range as those generated using the full-sized Superpave shear test equipment described in AASHTO TP7; moreover, these results were found to be fairly sensitive to changes in hot mix asphalt (HMA) composition. However, while the data repeatability of the redesigned FST is similar to other methods for measuring HMA stiffness, it remains too high for QC/QA testing. [More] | |
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260 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
9/5/2001
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there had been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program (NCHRP), authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 2001 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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259 - Guidelines for the Effective Use and Procurement of Advanced Warning Arrow Panels
11/5/2001
This digest provides procedures to ensure the proper visibility, deployment, and maintenance of advanced warning arrow panels. The digest also includes recommended specifications for arrow panels. The contents are as follows: Introduction; Technical Requirements for Arrow Panel Recognition; Development of a Specification for Arrow Panel Lamps; Development of a General Arrow Panel Specification; Procedures to Ensure Proper Arrow Panel Visibility; Final Report Availability; Acknowledgments; References; Appendix A: Photometric Procedure; Appendix B: Recommended Specification for Advanced Warning Arrow Panels; Appendix C: Maintenance Personnel Procedures to Ensure Proper Visibility of Arrow Panel; and Appendix D: Procedures for Field Personnel to Deploy to Maintain In-Service Arrow Panel Visibility. [More] | |
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258 - Development of a Computer Model for Multimodal, Multicriteria Transportation Investment Analysis
9/25/2001
This digest provides the details on and discusses the concepts of a software package (the Transportation Decision Analysis Software, or TransDec) to assist state and local planners in making alternative decisions on modal investment. Working with multiple investment alternatives, objectives that are often contradictory, and measures that do not lend themselves well to quantification is a daunting task made even more difficult by the need to demonstrate consideration of multiple effects of policy decisions. To ease the management of the process, this computer model guides the transportation practitioner through the multimodal, multicriteria analytical framework. TransDec systematizes the mechanics of performing multicriteria investment analysis and relieves transportation planners of the computational burden imposed by the framework. [More] | |
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257 - Effective Motivation of Highway Maintenance
8/3/2001
This digest describes a training course for motivating highway maintenance personnel. The course is particularly suited for first and second line supervisors of state, county, and city maintenance organizations. National Cooperative Highway Research Program (NCHRP) Project 14-11, completed in 1992, developed a training manual and corresponding teaching materials for a course on effective motivation of highway maintenance workers. A pilot presentation of the course materials indicated that the training course was useful but that enhancements were necessary. NCHRP Project 14-11(2) was initiated to address this need. The research, completed in late 2000, presented, on a CD-ROM, course material consisting of a participant workbook and an instructor's manual for effective motivation of highway maintenance personnel. This digest provides a summary of the work performed in this research. [More] | |
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256 - Strategic Plan for Improving Roadside Safety
6/22/2001
This digest provides an overview of a strategic plan for improving roadside safety. Many of the action items outlined in the plan can be immediately implemented by safety practitioners at minimal or no cost. The strategic plan represents the ideas and thoughts of nearly 200 roadside safety professionals. The final report, which this digest is based on, is published on-line as NCHRP Web Document 33. [More] | |
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255 - Impacts of Resurfacing Projects With and Without Additional Safety Improvements
6/18/2001
This digest describes the findings of a study to determine if there is a difference in the crash performance of resurfacing projects with and without safety improvements. Although the results were inconclusive, the study provides recommendations for conducting future studies and will be of interest to safety practitioners. This digest is based on a draft final report prepared by W.E. Hughes, L.M. Prothe, and H.W. McGee of Bellomo McGee, Inc., and E. Hauer, Consultant. [More] | |
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254 - Assessing Pavement Layer Condition Using Deflection Data
7/5/2001
An NCHRP digest of the findings from the final report on NCHRP Project 10-48, "Assessing Pavement Layer Condition Using Deflection Data," conducted by North Carolina State University. Dr. Y. R. Kim served as Principal Investigator. The agency's final report gives a detailed account of the project, findings, and conclusions, including software for the analysis of the condition of layers of full-depth AC pavements and AC pavements with untreated granular bases. The report, which was distributed to NCHRP sponsors (I.e., the state departments of transportation), is available for loan on request to the National Cooperative Highway Research Program, Transportation Research Board, 2101 Constitution Avenue, N.W., Washington, DC 20418. [More] | |
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253 - Recommended Use of Reclaimed Asphalt Pavement in the Superpave Mix Design Method: Guidelines
3/26/2001
These guidelines are intended as reference material for agencies and hot- mix asphalt (HMA) producers using reclaimed asphalt pavement (RAP) in Superpave (registered trademark). They include recommendations on aspects of sampling, testing, designing, producing, and placing Superpave mixtures with RAP. The guidelines are written for the engineers and supervisors selecting or approving RAP mixtures. The contents are organized as follows: Introduction; Determining the Properties of RAP; Determining RAP Binder Properties; Developing the Mix Design; and Field Quality Control- Quality Assurance Testing. A glossary and an appendix containing equations and flow charts are provided. [More] | |
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252 - Development and Demonstration of StratBENCOST Procedure
4/30/2001
This digest provides the details and concepts of a strategic, decision- support tool (StratBENCOST) that will be of interest to highway-planning and budget professionals. It summarizes the capabilities of the StratBENCOST software and highlights example applications. StratBENCOST is designed to assist in comparing large numbers of project options in a jurisdiction, including project options in the concept stage. [More] | |
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251 - Guidance for Selecting Compensatory Wetland Mitigation Options
1/30/2001
This digest summarizes the research and findings to date of National Cooperative Highway Research Program Project 25-16, "Guidance for Selecting Compensatory Wetland Mitigation Options." This digest presents state department of transportation managers with the best available information on wetland mitigation options and compares the success rates of individual mitigation with those of consolidated mitigation. [More] | |
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250 - Improved Visibility for Snowplowing Operations
11/15/2000
This digest describes several means, identified in National Cooperative Highway Research Program Project 6-12, that could improve visibility for snowplowing operations. The research, completed in 1999, identified several means for improving visibility for snowplowing operations. However, limited tests were conducted in this project to fully evaluate the merits of these means or the practicality of their unlimited use by highway agencies. This digest provides a summary of the work performed in this research. The material included in this digest is extracted from the final report on this project. The final report is available for loan on request to the National Cooperative Highway Research Program, Transportation Research Board, 2101 Constitution Avenue, N.W., Washington, DC 20418. [More] | |
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249 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
10/17/2000
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there had been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program (NCHRP), authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. In includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 2000 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and ( 5) Index to Syntheses and Studies. [More] | |
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248 - Updated and Enhanced Database for Macroeconomic Analysis of Transportation Investments and Economic Performance
5/31/2000
This digest summarizes the findings of National Cooperative Highway Research Program (NCHRP) Project 2-17(3)A. The project updated and expanded the database developed in NCHRP Project 2-17(3), which is a disaggregate data set that includes information on different types of public infrastructure, private economic activity within different industries, and national data by region or state. This digest is based on a draft final report prepared by Michael E. Bell of MEB Associates, Inc., for the Institute for Policy Studies at Johns Hopkins University. [More] | |
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247 - The Relationship Between Access Density and Accident Rates: Comparisons of NCHRP Report 420 and Minnesota Data
6/16/2000
This digest summarizes findings of National Cooperative Highway Research Program (NCHRP) Project 3-52A, "Impacts of Access-Management Techniques." NCHRP Report 420, "Impacts of Access Management Techniques" (1999), presents relationships between access density and accident rates. This digest uses additional data from Minnesota to confirm these relationships. The digest is organized as follows: Introduction; Problem Statement; Objective and Approach; Background; Results; Comparisons; and Accident Rate Indices. [More] | |
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245 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
8/24/1999
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day to day work. Because there had been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 1999 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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243 - Proposed Design Guidelines for Reducing Hydroplaning on New and Rehabilitated Pavements
10/14/1999
This digest summarizes proposed design guidelines for reducing hydroplaning on new and rehabilitated pavements developed in NCHRP Project 1-29, "Improved Surface Drainage of Pavements." In this study, and in the PAVDRN computer program, tread depth was assumed to be 3/32 in. (2.38 mm) and tire pressure was assumed to be 24.0 psi (16.75 kPa). These values were selected because the data that were available to the authors for extending the range of the hydroplaning algorithm used in PAVDRN were also based on these assumptions. Four key areas need to be considered in order to analyze and eventually minimize the potential for hydroplaning. These areas are environmental conditions, properties of the pavement surface, geometry of the roadway surface, and the use of drainage appurtenances. Each of these areas and its influence on the resulting hydroplaning speed of the designed section is discussed in detail in this digest. Five geometric design sections, one for each of the basic geometric configurations used in highway design, are considered in the proposed design guidelines: tangent, curve, transition, crest vertical curve, and sag vertical curve. Finally, the use of drainage appurtenances is reviewed. Drainage appurtenances considered include longitudinal edge drains, slotted drains located between travel lanes, and transverse drains. [More] | |
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242 - Metrication and Enhancement of MicroBENCOST Software Package
7/13/1999
This is a digest of National Cooperative Highway Research Program ( NCHRP) Project 7-12(2), "Metrication and Enhancements of MicroBENCOST Software Package." The digest provides details and concepts about a software package consisting of two independent programs on separate disks--an English units version (C:/ MBE) and a metric units version ( C:/ MBM)--that update and enhance the original English unit program ( C:/ MB). All programs are written in the FORTRAN programming language and use the DOS operating system. The MicroBENCOST software provides a planning-level economic analysis tool that can be used to analyze a variety of transportation projects. [More] | |
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241 - 1998 Scanning Review of European Practice for Bridge Scour and Stream Instability Countermeasures
8/5/1999
This digest summarizes the findings of an international technology scanning review conducted with the support of National Cooperative Highway Research Program (NCHRP) Project 20-36, "Highway Research and Technology--International Information Sharing." The scanning review team consisted of representatives from U.S. federal and state agencies as well as the private sector. The review included visits to highway research institutes, hydraulic research laboratories, and field sites in Switzerland, Germany, the Netherlands, and the United Kingdom. Although the review concentrated on bridge scour and stream instability countermeasures, the scanning review team members' inquiries were wide- ranging and included basic scour technology for evaluation and design, laboratory and field research programs, environmental issues, and bioengineering techniques. [More] | |
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240 - Conversion of AASHTO Documents to Metric Units
7/18/1999
This digest summarizes the findings from the final report on National Cooperative Highway Research Program (NCHRP) Project 20-40, "Conversion of AASHTO Publications to Metric Units." The work involved converting 16 major American Association of State Highway and Transportation Officials (AASHTO) publications to the SI (metric) system of measurement units and providing them to AASHTO in reproducible format suitable for publication. This digest discusses the research agency's experience with the conversion of each specific AASHTO document and estimates the time and funds expended for each conversion. Finally, it presents guidelines for the efficient conversion of complex technical documents to assist public agencies tackling this difficult issue. [More] | |
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239 - Improved Safety Information for Highway Design
6/1/1999
This digest of NCHRP Project 17-12, "Improved Safety Information for Highway Design," provides details and concepts for improved safety information systems that will be of interest to highway designers, safety professionals, and information managers. The project identified the critical safety information needed to support project- and policy- level decision making in highway design and to develop the fundamental architecture for systems to acquire, store, access, and use safety information in highway design. [More] | |
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238 - Report on the 1998 Scanning Review of European Winter Service Technology
5/27/1999
This digest describes the findings of the 1998 International Scanning Review of European Winter Service Technology organized jointly under the auspices of the Federal Highway Administration's (FHWA's) International Outreach Program and the American Association of State Highway and Transportation Officials (AASHTO) through the National Cooperative Highway Research Program (NCHRP). The review was undertaken to examine several Japanese and European technologies for winter maintenance originally identified by the 1994 International Winter Maintenance Technology Scanning Review as prime candidates for further, detailed investigation, viz, new sensor developments, integration of winter service road condition in IVHS technology, and pavement anti-icing and deicing systems. The 1998 European scanning review (conducted from March 6 to March 22) was organized to enable team members to do the following: Discover, understand, publicize, and assist with the marketing of state-of-the-art developments in winter maintenance technology and techniques; Focus on methods, equipment, and processes to improve customer service and awareness; Make recommendations on the development and implementation of customer-based performance measures; and Assist state and local agencies to implement state-of-the-art technologies and techniques by using the resources of FHWA, AASHTO, the National Association of County Engineers (NACE), the American Public Works Association (APWA), and the Transportation Research Board (TRB). Chapter 2 of this digest presents the country summaries for Switzerland, France, Norway and Sweden. Chapter 3 contains observations, discussions and recommendations in the following areas: public information and education programs; use of studded tires; road-weather information systems; snow removal in urban areas; performance measures and contracting for winter service; computer-assisted dispatch and other technology applications; Traffic Management Centers; avalanche protection and control; and other equipment, materials, and methods. [More] | |
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237 - Superpave Gyratory Compaction Guidelines
4/1/1999
This digest summarizes key results of NCHRP Project 9-9, "Refinement of the Superpave Gyratory Compaction Procedure." Of particular interest, it presents a recommended reduction in the Ndesign table in AASHTO PP28, "Practice for Designing Superpave HMA," from the original 28 traffic and climate combinations to 4, provides specific Ndesign levels for base mixes, and recommends setting the Superpave short-term aging mix temperature equal to the equiviscous compaction temperature. The Superpave gyratory compaction procedure, developed under the Strategic Highway Research Program (SHRP), is the method required for all Superpave mix designs and mixture process control. The gyratory compactor must provide a density in the compacted laboratory specimen that closely approximates the ultimate density of the hot mix asphalt (HMA) mixture obtained in the pavement when subjected to traffic loads and climate conditions so that an appropriate optimum asphalt content can be selected during the laboratory mix design process. [More] | |
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236 - Emerging Models for Delivering Transportation Programs and Services: A Report of the Transportation Agency Organization and Management Scan Tour
4/1/1999
This digest summarizes the findings of an international technology scanning review conducted with the support of National Cooperative Highway Research Program (NCHRP) Project 20-36, Highway Research and Technology - International Information Sharing. The scanning review team consisted of representatives from U.S. federal, state, and private sector agencies. They examined how other developed countries are coping with budgetary constraints that lead to downsizing and restructuring of their transportation agencies. The countries visited were Australia, New Zealand, Sweden, and the United Kingdom. For each country, findings are reported in the following areas: (1) general background and organizational structure; (2) roles of government and the private sector in the delivery and maintenance of transportation facilities; (3) use of performance measures for producing programs and products and for allocating resources; and (4) innovative approaches for developing and implementing highway programs. [More] | |
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235 - Assessment of Impacts of Bridge Deck Runoff Contaminants on Receiving Waters
1/24/1999
This digest summarizes the initial results of in-progress research associated with the assessment of bridge deck runoff impacts on receiving waters. It presents the findings of a critical review of scientific and technical literature on water-quality impacts and assessment methods for bridge deck runoff, maintenance practices, and spills. The digest also presents the results of a survey of state and provincial highway agencies addressing mitigation measures currently employed or being considered for bridge deck runoff, maintenance activities, and spills. This information will be especially timely for practitioners interested in current literature and practices associated with bridge runoff. [More] | |
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234 - Manual for Bridge Rating Through Load Testing
10/1/1998
This digest describes the research findings from National Cooperative Highway Research Program (NCHRP) Project 12-28(13)A, Bridge Rating Through Nondestructive Load Testing. The project developed and documented processes for performing load tests and using the test results to calculate bridge ratings. The research results are presented in the form of a manual, which provides guidelines for integrating the load testing of bridges with their load rating. The manual is supplemented with a technical report, which presents detailed data on two major technical areas - evaluating unintended composite action and establishing target proof load levels. The contents of the manual are as follows: (1) Introduction; (2) General Considerations; (3) Factors Which Influence the Load-Carrying Capacity of Bridges; (4) General Load Testing Procedures; (5) Load Test Equipment and Measurements; (6) Diagnostic Load Tests; (7) Proof Load Tests; (8) Posting and Permit Considerations; (9) Illustrative Examples; Appendix A - Review of Bridge Load Tests; Appendix B - Procedures for Field Evaluation of Live Load Impact; and Appendix C - Fatigue Life Testing for Steel Bridges. [More] | |
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233 - Summary of Economic Development Research Projects
1/24/1999
This staff digest summarizes the scope and status of current or recently completed National Cooperative Highway Research Program ( NCHRP) and Transit Cooperative Research Program (TCRP) research activities associated with economics and economic development. The digest provides brief descriptions, summaries of objectives, status, and other information. It is intended to give a quick overview of the range of economic research activities being administered through the Cooperative Research Programs of the Transportation Research Board. [More] | |
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232 - Report on the 1997 Scanning Review of Asian Bridge Structures
12/31/1998
This digest describes the findings of an international scanning tour undertaken to obtain a broad overview of bridge design, materials technology, construction procedures, and maintenance practices in Asia. The scanning team focused on identifying technological developments in Asia that have the potential for application in the United States. In addition, the team shared information with their international counterparts on U.S. practices in highway bridge construction, maintenance, and management to promote international exchange and cooperation. The scanning tour concentrated on the following topics: Design standards, codes, and specifications; Design and construction practices; Materials, fabrication, and joining techniques; Bridge protection strategies; Inspection and rehabilitation practices; Programming and management practices; and Innovations. The review was performed by an 11-member team representing several of the states, the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the National Cooperative Highway Research Program. The scanning tour took place from September 12 through September 28, 1997, and involved visits to Japan, South Korea, and Taiwan. In all three countries, site visits were made to major bridges. On the basis of the observations made during the scanning review, the team developed a list of 30 topics for possible application in the United States. The list was then divided into 6 high-priority topics, 7 medium- priority topics, and 17 other topics for consideration at a later date. [More] | |
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231 - Economic Effects of Restricting Left Turns
10/1/1998
This digest summarizes the findings from the final report on National Cooperative Highway Research Program (NCHRP) Project 25-4, Economic Effects of Restricting Left Turns, conducted by Cambridge Systematics, Inc., JHK & Associates, Inc., and HBRS, Inc. G.E. Weisbrod and R. Neuwirth were the principal investigators. This digest will help analysts assess the effect of left-turn restrictions on businesses and describes ways to mitigate those effects. The digest will be of interest to those planning, designing, and constructing left-turn restrictions, regardless of whether the projects are permanent or temporary (in the latter case, being the result of construction or maintenance). The final report for this project will not be published but a copy has been sent to each state's department of transportation. [More] | |
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230 - Review of Travel Assumptions Employed in Emission Factor Models
11/21/1998
This is a digest of the findings from National Cooperative Highway Research Program (NCHRP) Project 8-33, Quantifying Air Quality and Other Benefits and Costs of Transportation Control Measures. The objective of the project is to develop an improved analytical framework for evaluating the air quality and other benefits and costs of transportation control measures. The objective of the task summarized in this digest was to describe important transportation-related assumptions embedded within the emission factor models developed by the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board. This digest is based on the interim project report. The contents are organized as follows: Summary; Introduction; EPA's MOBILE5 Emissions Factor Model; Light-Duty Vehicle Travel Assumptions in MOBILE5; Heavy-Duty Vehicle Travel Assumptions in MOBILE5; California's MVEI7G Emissions Model; The MVEI7G Weight Submodel; and The MVEI7G Burden Submodel. [More] | |
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229 - Developing Measures of Effectiveness for Truck Weight Enforcement Activities
8/1/1998
This digest describes the findings of National Cooperative Highway Research Program (NCHRP) Project 20-34, Developing Measures of Effectiveness for Truck Weight Enforcement Activities, conducted by Fred R. Hanscom, Transportation Research Corporation, Haymarket, Virginia. The digest provides the practitioner with procedures for evaluating truck weight enforcement activities. It employs a set of measures of effectiveness (MOEs) that were developed on the basis of specific truck weight enforcement objectives. Final MOEs were selected on the basis of their ranked abilities to meet highway and enforcement agency needs and then validated in a four-state study to confirm their sensitivity to actual enforcement activity. Sampling procedures and data analysis operations required to apply the MOEs are also described. [More] | |
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228 - Development of Training Material for Highway Construction Personnel
7/1/1998
This digest reports the findings from the final report on National Cooperative Highway Research Program (NCHRP) Project 20-25(3), Development of Training Material for Highway Construction Personnel, conducted by SNI International Resources, Inc. Mr. Richard P. White served as Principal Investigator. In this third phase of the research project, completed in 1997, comprehensive training packages for teaching 12 courses were developed. The plan, developed in the earlier phase of research, for promoting and facilitating the use of the recommended training program was also reviewed and revised. [More] | |
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227 - Systems for Design of Highway Pavements
8/1/1998
This digest provides a summary of the findings from the final report on National Cooperative Highway Research Program (NCHRP) Project 1-32, Systems for Design of Highway Pavements conducted by ERES Consultants, Inc., for which Dr. Michael I. Darter served as Principal Investigator. The research, completed in 1997, provided (1) a catalog of current state pavement design features, (2) a catalog of recommended (good practice) pavement design features, and (3) a prototype knowledge-based expert system. [More] | |
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226 - Multimodal Transportation: Development of a Performance-Based Planning Process
8/1/1998
In recent years, national transportation policy has evolved to support the development of multimodal systems and services tailored to local conditions for improved efficiency and performance. This digest describes how performance-based transportation planning and decision making can be established to effectively guide transportation investment and operational decisions. It is intended to assist transportation planners, policy officials, and other practitioners in improving the transportation planning processes at the state, metropolitan, and local levels. It also presents an action plan for Phase II of the research, which will produce a guidance manual for state departments of transportation, metropolitan planning organizations, and other transportation planning organizations. [More] | |
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225 - Putting Research Into Practice: A Synopsis of Successful Strategies and Case Histories
6/3/1998
This digest summarizes implementation practices leading to the successful and timely application of research findings, and illustrates the use of these practices in several case studies drawn from the research findings. The contents are organized as follows: (I) Introduction; (II) Background Conditions Favoring Innovation; (III) Strategies to Put Research into Practice; (IV) Long-Term Success; and ( V) Case Histories. Much of the information contained in this digest is extracted from the findings of NCHRP Project 20-33, Facilitating the Implementation of Research Findings performed by RAND for which Dr. Tora K. Bikson served as principal investigator. [More] | |
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224 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
9/1/1998
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there had been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, Synthesis of Information Related to Highway Problems. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 1998 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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223 - Development of an Improved Framework for the Analysis of Air Quality and Other Benefits and Costs of Transportation Control Measures
3/31/1998
This digest summarizes the findings from Phase I of National Cooperative Highway Research Program (NCHRP) Project 8-33, Quantifying Air Quality and Other Benefits and Costs of Transportation Control Measures. The objective of Project 8-33 is to develop an improved analytical framework for evaluating transportation control measures. The objectives of the particular tasks summarized in this digest were to outline the desirable long-term characteristics for an improved analysis framework and to identify techniques that could be implemented immediately by state departments of transportation and metropolitan planning organizations. The framework described in this digest is being tested and refined in subsequent phases of the research. This digest will be particularly useful to planners considering upgrading their transportation planning process. [More] | |
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222 - Pavement Marking Assessment System (PAMAS)
1/14/1998
This digest contains a brief description of and the operating instructions for a computer program that simplifies the semiquantitative process for measuring the engineering performance, environmental performance, including the impact of volatile organic compounds (VOCs), and health concerns, including an evaluation of the hazardous air pollutants (HAPs), of various classes of conventional pavement marking materials used for highway stripes. This computer program is especially timely because the United States Environmental Protection Agency is expected to regulate the permissible amounts of VOCs in paints and coatings early in 1998. This regulation might proscribe the use of most presently available solvent-borne paints and some water-based paints. [More] | |
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221 - Development of System and Application Architectures for Geographic Information Systems in Transportation
3/19/1998
This digest describes generic, spatially oriented models of department of transportation (DOT) data and activities developed under National Cooperative Highway Research Program (NCHRP) Project 20-27(2), Development of System and Application Architectures for Geographic Information Systems in Transportation (GIS-T). The need for development of enterprise information architectures to facilitate integrated transportation information systems was addressed using information engineering methods. The generic models can serve as templates for transportation agencies embarking upon information strategy planning to reduce high initial costs. DOT decision makers, information managers, and consultants working for transportation agencies should find the generic models useful and the explanation of Utah DOT's experience informative. Analysis of the interactions between data and activities in the generic models revealed a series of generic business systems, each encompassing a closely coupled group of activities and data. Some of the business systems, especially those that support policy development and location referencing, were determined to be foundational in nature. That is, all other business systems depend upon data created, collected, or managed by the foundational systems. All business systems involved with infrastructure management are highly spatial in nature, as are many of those involved with agency management. This suggests that GIS has high priority among the appropriate technologies for information system implementation. The experience of the Utah DOT in using a template- based approach to information strategy planning is described in some detail. Utah realized a savings of around 67% in comparison to the average cost of information strategy planning at other DOTs. The generic data and activity models produced by this research are at a higher level of detail than the template models that were available to UDOT. This means that more effort will need to be devoted to adding detail to these products to meet the specific circumstances of any one agency. However, the potential for significant savings remains.C [More] | |
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220 - Strategies for Improving Roadside Safety
12/19/1997
This digest is an excerpt of a report prepared under National Cooperative Highway Research Program (NCHRP) Project 17-13, Strategic Plan for Improving Roadside Safety. The digest includes the following sections: (1) Roadside Crashes: A Serious Highway Safety Problem; (2) Addressing the Roadside Safety Problem; (3) A Vision for Improved Roadside Safety; and (4) Translating the Vision into Actions. [More] | |
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219 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
9/3/1997
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there has been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, Synthesis of Information Related to Highway Problems. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 1997 Program; (3) NCHRP Project Committee SP20-5; Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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218 - A Generic Data Model for Linear Referencing Systems
9/24/1997
This digest describes a consensus location referencing data model that was developed under NCHRP Project 20-27(2), Systems and Applications Architecture for GIS-T. The model allows linkages to various types of data over all modes. This information will be of use to persons involved with the design and implementation of field location referencing systems as well as the structuring of agency databases for location referencing. [More] | |
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217 - Relationship Between Implemented Transportation Control Measures and Measured Pollutant Levels
7/28/1997
This digest summarizes partial findings from Phase I of NCHRP Project 8- 33, Quantifying Air Quality and Other Benefits and Costs of Transportation Control Measures. The objective of the project is to develop an improved analytical framework for evaluating transportation control measures (TCMs). The objective of the task summarized in this digest was to examine the relationships between implemented TCMs and measured air pollutant concentrations. [More] | |
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216 - Illumination Guidelines for Nighttime Highway Work
12/11/1996
This digest presents the findings from the final report on NCHRP Project 5-13, Illumination Guidelines for Nighttime Highway Work. Nighttime construction and maintenance work is performed by at least 24 state departments of transportation. The preliminary guidelines are intended to assist in planning, designing, and operating nighttime highway work zone lighting systems. These guidelines address visibility requirements, lighting equipment, lighting configuration and arrangement, lighting system design, system operation and maintenance, and economic considerations. [More] | |
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215 - Protocol for In-Service Evaluation of Bridges with Epoxy-Coated Reinforcing Steel
1/2/1997
This digest announces the results of NCHRP Project 10-37B, Protocol for the Evaluation of Existing Bridges Containing Epoxy-Coated Reinforcing Steel. Research and experience indicate the potential for future failures in the performance of epoxy-coated reinforcing steel in concrete bridges. Although not yet experiencing failures and seeing little sign they will, many transportation departments will be examining their existing structures in light of this potential for failure. To foster a better understanding of the problem, a resource document to guide these examinations and to provide some uniformity in the data collected has been prepared. The data to be collected will help define failure mechanisms, improve the prediction of failures, and guide improvements in the corrosion protection of reinforced concrete bridges. [More] | |
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214 - On-Site Evaluation and Calibration Procedures for Weigh-In-Motion Systems
2/7/1997
This digest presents the findings from the final report on NCHRP Project 3-39(2), On-Site Evaluation and Calibration Procedures for Weigh-In-Motion Systems. Widely accepted procedures do not exist for on-site evaluation and calibration of Weigh-In-Motion (WIM) systems. The feasibility of two approaches for evaluating and calibrating these systems were examined. One approach involves a combination of test trucks and vehicle simulation models and the other uses automatic vehicle identification (AVI) equipment. [More] | |
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213 - Nondestructive Testing of Unknown Subsurface Bridge Foundations - Results of NCHRP Project 21-5
12/11/1996
This digest presents the findings of NCHRP Project 21-5, Determination of Unknown Subsurface Bridge Foundations, which evaluates existing and new technologies for use in determining unknown subsurface bridge foundation characteristics. The digest contains information about the feasibility of using nondestructive test (NDT) methods for the determination of unknown depths of bridge foundations. This will be of interest to bridge and other structural engineers; soils, geology, and foundation engineers; and materials and construction engineers. Foundation depth information, in particular, is needed for performing an accurate scour evaluation at each bridge site, along with as much other information on foundation type, geometry, materials, and subsurface conditions as can be obtained. [More] | |
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212 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
7/11/1996
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there has been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, Synthesis of Information Related to Highway Problems. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes five tables: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 1996 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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211 - Current State Practices in Transportation-Tourism Interface
4/2/1996
This digest presents the findings of Phase I of NCHRP Project 2-17(6), Tourism Travel Contributions to Economic Development. This two-phase project is designed to examine and refine the institutional practices of the agencies that are counterparts in the transportation-tourism interface: state transportation agencies (DOTs) and state tourism offices (STOs). Phase I involved a series of data collection and analysis tasks structured to produce an overview of the current state of knowledge and practice in the transportation-tourism interface. The Phase I findings, along with brief discussions, are grouped according to the following three topics: (1) overall policy and institutional coordination; (2) consideration of tourism in statewide planning and programming; and (3) traveler information services. The issues identified in the research so far touch all aspects of the DOT planning process: policies, processes, procedures, and programs. Each state has its unique DOT and STO organizational structure and objectives for tourism to enhance local resources; however, as in any interagency coordination effort, common factors must be addressed. [More] | |
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210 - Effects of Highway Bypasses on Rural Communities and Small Urban Areas
5/9/1996
This staff digest summarizes a study conducted as part of NCHRP Project 20-5, Synthesis of Information Related to Highway Problems, on the impacts of highway bypasses on rural communities and urban areas of less than 50,000 population, and current practices in using this knowledge in the planning of bypass development. The study involved a survey questionnaire to all U.S. state and Canadian provincial departments of transportation and a review of published literature and agency supplied studies. The literature review determined that there is no clear consensus on study procedures and analysis methods that should be used in bypass impact studies. The studies reviewed suggested that, for the most part, bypasses seem to have favorable impact on rural communities and small urban areas but evidence in these studies is often weak. Interviews and surveys of residents and businesses indicate that bypasses increase development potential along the fringe areas served by the new route, and at the same time relieve congestion, safety hazards, and other undesirable conditions in the central areas from which traffic is diverted. In most cases, adverse effects on otherwise viable bypassed businesses appeared to be largely recouped by improved ambiance for patrons and residents in the community, although individual businesses may suffer when a new bypass is opened. Agencies report a variety of measures to avoid or mitigate the adverse impacts of a bypass. The research literature provides no particular guidance on whether such measures have significant effect on bypass impact. [More] | |
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209 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
12/31/1995
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there has been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, Synthesis of Information Related to Highway Problems. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. It includes four tables: (1) Topics Being Studied; (2) NCHRP Project Committee SP20-5; (3) Completed Syntheses; and (4) Index to Syntheses and Studies. [More] | |
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208 - Durability Testing of High-Strength Concrete Containing High-Range, Water-Reducing Admixtures
3/8/1996
This digest has been derived by excerpting the agency report for NCHRP Project 10-32A, Durability Testing of High-Strength Concrete Containing High-Range, Water-Reducing Admixtures. For this project, laboratory freezing and thawing tests were used to evaluate the durability of concretes containing high-range, water-reducing admixtures (i.e., superplasticizers). Two types of concretes were studied--the first had the desired range of slump and air-void system with the admixtures, the second had the desired range of slump and air- void system without the admixtures. To this second concrete, the admixtures were added in order to increase the slump significantly. Among the overall findings of this research was that the characteristics of a well-developed air void system normally associated with durable concretes also are required for durable concretes containing high-range water-reducing admixtures. [More] | |
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207 - On the Implementation of Research Findings in Surface Transportation
6/20/1995
To improve technology transfer and facilitate the rapid use of research findings in surface transportation, there is a need to recognize and address the significant factors that influence implementation, to identify the characteristics of organizations that have succeeded in being innovative, and to develop and apply strategies for the creation of an environment conducive to innovation and timely application of research findings. NCHRP Project 20-33, Facilitating the Implementation of Research Findings, was initiated, with partial funding provided by the Federal Highway Administration (FHWA), to address this need. The first phase of research, completed in late 1994, focused on identifying the factors affecting implementation of research findings, strategies that are expected to promote this implementation, and themes for future research to test the more viable strategies for moving transportation research results into practice. To better understand implementation issues and formulate recommendations for addressing them, the second phase of research--to be completed in late 1995--will involve a nationwide survey of transportation industry organizations to identify successful implementation practices. This Digest provides a summary of Phase I. These are interim findings, which may be revised at the completion of the research. The material in this Digest is extracted from an interim report on the project. The Digest is organized as follows: Introduction; Findings; Strategies for Promoting Implementation; Themes for Future Research; Conclusions; Interim Report (reference citation); and Appendix A: Future Research Themes (with priority ratings). [More] | |
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206 - Training for Highway Construction Personnel
3/24/1995
An initial phase of research conducted under NCHRP Project 20-25, Training Needs for Highway Construction Personnel, developed a national training program that included 62 training courses and determined that the National Institute for Certification in Engineering Technologies (NICET), founded by the National Society of Professional Engineers (NSPE), is the most reliable yardstick available for measuring highway construction knowledge and ability. A second phase of research conducted under NCHRP Project 20-25(2), Training for Highway Construction Personnel, consolidated the 62 courses into 45 courses and developed descriptions and lesson-plan outlines for each of these courses. Also, comprehensive training packages were developed for teaching these courses. In addition, a plan was developed for promoting and facilitating the use of the recommended training program for highway construction personnel. This digest provides a description of the work performed in the second phase of research. The material in this digest is extracted from the final report on this project. [More] | |
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205 - Requirements for Application of Light Emitting Diodes (LEDs) to Traffic Control Signals
4/18/1995
Incandescent lamps are presently the major illumination source for traffic signals. They are, however, inefficient compared with other light sources. Maintenance costs are high for these lamps, and the light output degrades as the lamp ages. These problems--plus the ever- increasing cost of energy--justify considering other light sources. One alternative is light emitting diodes (LEDs). Before existing incandescent lamps are replaced by LEDs, it is necessary to show that LED signals will meet applicable standards for color and intensity, will not adversely affect the safety or operation of the roadway, and will be economically advantageous. NCHRP Project 5-12 was initiated in response to these needs. The objective of the research was to determine the feasibility and implementation potential of LEDs. The project found that red and Portland Orange (pedestrian) LED signals are currently feasible. This digest summarizes the project findings and includes testing results, a discussion of economic analysis, specification guidelines, recommendations for LED use, and suggested future research. The digest will be of interest to those involved in designing and specifying traffic signals. [More] | |
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204 - Winter Maintenance Technology and Practices - Learning from Abroad
2/9/1995
An International Winter Maintenance Technology Scanning Tour was organized jointly under the auspices of the Federal Highway Administration's International Outreach Program and the AASHTO- sponsored National Cooperative Highway Research Program to examine snow and ice control operations in Japan and Europe for technology with potential for domestic application. The scanning team travelled to Japan and Europe in March 1994 and discovered important differences in snow removal equipment, anti-icing/deicing materials and methods, weather monitoring, winter hazard mitigation, and road user information services. Also, the team discovered important differences in the public perception and responsibility for participation in snow removal operations, the methods employed for financing winter maintenance operations, and the cooperation between public agencies and private enterprise in research and development efforts. This Digest presents the findings and recommendations of the scanning team. [More] | |
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203 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
2/8/1995
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. Because there has been no systematic means for bringing such useful information together and making it available to the entire highway community, the American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, Synthesis of Information Related to Highway Problems. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest summarizes the progress and status of NCHRP Project 20-5. It includes four tables: (1) Topics Being Studied; (2) NCHRP Project Committee SP20-5; (3) Completed Syntheses; and (4) Index to Syntheses and Studies. [More] | |
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202 - Congestion Impacts on Business and Strategies to Mitigate Them
9/18/1995
This NCHRP digest summarizes the findings from the final report of NCHRP Project 2-17(5), Impact of Urban Congestion on Business, conducted by Cambridge Systematics, Inc. Principal authors were L.R. Grenzeback and M.G. Warner. A copy of the report, which will not be published, has been sent to each state department of transportation. The digest provides a typology of congestion impacts, discusses how congestion affects different types of businesses, and identifies ways some businesses have mitigated the impact of traffic congestion. The extensive use of interviews with business people helped create a clear view of their perspective. The digest will be of interest to those involved in assessing and mitigating the impacts of traffic congestion on business. [More] | |
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201 - BRI-STARS (Bridge Stream Tube Model for Alluvial River Simulation)
7/26/1994
This NCHRP digest describes the BRIdge Stream Tube model for Alluvial River Simulation (BRI-STARS), Version 3.3, an innovative, operational computer program developed for NCHRP Project 15-11, Computer-aided Analysis of Highway Encroachments on Mobile Boundary Streams. It is a semi-two-dimensional model capable of computing alluvial scour/ deposition through subcritical, supercritical, and a combination of both flow conditions involving hydraulic jumps. This model, unlike conventional water and sediment routing computer models, is capable of simulating channel widening/narrowing phenomenon as well as local scour due to highway encroachments. It couples a fixed-width stream tube computer model, which simulates the scour/deposition process taking place in the vertical direction across the channel, with a total stream power minimization algorithm. The decision making algorithm, using rate of energy dissipation or total stream power minimization, determines whether the simulated sediment erosion satisfying the sediment continuity equation should take place in the lateral or vertical direction. It is this second component that allows the lateral changes in channel geometries. Finally, the bridge component allows computation of the hydraulic flow variables and the resulting scour due to highway encroachments. The model also contains a rule- based expert system program for classifying streams by size, bed and bank material stability, platform geometry, and other hydraulic and morphological features. [More] | |
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200 - Objectives and Decision Criteria for Infrastructure Investment
2/21/1995
The National Cooperative Highway Research Program (NCHRP) has undertaken various research efforts to develop cost-benefit analysis techniques. NCHRP Project 2-17(1), Methodologies for Evaluating the Effects of Transportation Policies on the Economy, developed a Primer for applying the cost-benefit techniques to analyze transportation investments considering a wide range of factors. This Digest describes the application of the cost-benefit procedures outlined in the Primer for the purpose of assessing transportation investment options at the national scale. Although this effort was aimed at the national level, it is believed that variations of the techniques described herein will be useful to state, regional, and local governments in making investment decisions. The Digest is presented in 4 chapters. Chapter 1 discusses the problem and its solution. Chapter 2 examines appropriate objectives for infrastructure investment. Chapter 3 presents a framework for promoting growth-oriented public capital formation, identifies the appropriate decision criteria and corresponding appraisal methodologies for use in identifying growth- related infrastructure projects, and discusses ways in which the federal government can create incentives for states and localities to apply these objectives, criteria, and methodologies to ensure the optimum level, mix, and geographic distribution of public investment. The focus is on program changes that can be achieved immediately. Chapter 4 offers a brief conclusion. [More] | |
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199 - Rapid Static Surveying Using the Global Positioning System
1/1/1994
This Research Results Digest (RRD) is an update on RRD Number 185: NCHRP Supports Advances in Differential GPS Satellite Surveying, published in April 1992. The research has resulted in a technique by which highway engineers and surveyors may rapidly obtain precise positions necessary to maintain geodetic control. The technique uses measurements of the Global Positioning System (GPS), commercially available GPS receivers, and personal computers for data processing. Users of this technique need to occupy each point to be surveyed for only 1 or 2 min, without concern for cycle slips or other phase discontinuities in the phase data that commonly occur. Thus, this technique provides an efficient means to quickly and precisely survey a large number of points. Horizontal accuracies of 1 cm and vertical accuracies of 3 cm have been demonstrated. The software has been written to run on most available personal computers and can be operated with no special skills required. [More] | |
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198 - Development of Comprehensive Bridge Specifications and Commentary
6/15/1998
This digest details the development of the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. The contents are organized as follows: (1.0) Historical Development; (1.1) Project Background; (1.2) Organization of Project; (1.3) Project Objectives; (2. 0) Summary of Reliability Consideration; (2.1) Overview of a Probability-Based Specification; (2.2) Overview of the Calibration Process; (3.0) Suggested Research; (4.0) Acknowledgments; and (5.0) Bibliography. [More] | |
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197 - Fatigue Behavior of Welded and Mechanical splices in Reinforcing Steel
7/18/1994
This NCHRP Digest contains suggested revisions to the AASHTO Standard Specifications for Highway Bridges based on findings from the final report under NCHRP Project 10-35, which was initiated to evaluate the fatigue behavior of welded and mechanical splices for reinforcing bars in bridges and to develop practical design provisions. The research was accomplished by carrying out the following four tasks: a review and summary of published and unpublished literature; the design and conduct of a laboratory program of fatigue tests; a statistical analysis of the experimental results and those obtained from the literature; and the formulation of design guidelines. [More] | |
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196 - A Unique, Hands-On Educational Program for High School Mathematics and Science Classes
1/1/1994
This digest summarizes the background, research results, and prototype materials produced under the NCHRP Project 20-24(3)A, Civil Engineering Careers in Transportation--Outreach Program. The discussion provides information on the high school educational outreach program called TRAC (TRAnsportation and Civil engineering). TRAC, which began as a pilot project in September 1991, is working in six states--California, Florida, Maryland, New York, Pennsylvania, and Washington--to increase awareness about transportation and civil engineering. The primary targets of the TRAC career message are female and minority high school students. Right now, TRAC is focusing exclusively on creating awareness about civil engineering. It is expected that starting in Fall 1995 TRAC will begin to expand the scope of its career message by developing additional prototype materials that illustrate the practices of other fields within the transportation profession. [More] | |
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195 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1993
This is a digest of the progress and status of NCHRP Project 20-5, Synthesis of Information Related to Highway Problems, for which the Transportation Research Board is the agency conducting the research. This project is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constutite an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. The following five tables are included in this digest: (1) Topics Being Studied; (2) Synthesis Topics Selected for the FY 1994 Program; (3) NCHRP Project Committee SP20-5; (4) Completed Syntheses; and (5) Index to Syntheses and Studies. [More] | |
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194 - Low-Service-Level Guardrail Systems
1/1/1994
This is an NCHRP digest of the findings from the final report on NCHRP Project 22-5A, Warrants for the Installation of Low-Service-Level Guardrail Systems, conducted by Wilbur Smith Associates. Five low- service-level barrier systems were developed and evaluated by full- scale crash testing. In addition, a user's guide was prepared to provide design details for the developed systems and to outline specific warrants for their placement on low-volume roads. This digest provides a description of the developed low-service level barrier systems, test results, and the warranting procedure. [More] | |
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193 - Administration of Highway and Transportation Agencies Project 20-24 Series
1/1/1993
This is a digest on the progress of projects emanating from NCHRP Project 20-24, Administration of Highway and Transportation Agencies. To date, ten projects have been initiated. Four of these have been completed and the others are in progress. Brief synopses of the ten projects are provided. The completed projects are: Project 20- 24(1) - Using Market Research to Improve Management of Transportation Systems; Project 20-24(2) - Executive Management Information Systems for State Departments of Transportation; Project 20-24(4) - Senior Executive Support Program Participant's Manual; Project 20-24(6)A - Performance Measures Used by State Highway and Transportation Agencies; and Project 20-24(8) - Project 20-24 Series - Revisited. The active projects are: Project 20-24(3) - Expanding the Civil Engineering Pool; Project 20-24(3)A - Civil Engineering Careers in Transportation - Outreach Program; Project 20-24(5) - Public Outreach in Transportation Management; Project 20-24(6)B - Business Systems Plan for Highway Engineering Information; Project 20-24(7) - Alternatives to Motor Fuel Taxes for Financing Surface Transportation Improvements; Project 20-24( 9) - State Departments of Transportation--Strategies for Change; and Project 20-24(10) - Customer-Based Quality in Transportation. [More] | |
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192 - Procedure for Determining Work Zone Speed Limits
10/4/1996
This NCHRP Digest summarizes the findings of NCHRP Project 3-41, Procedure for Determining Work Zone Speed Limits. The Manual on Uniform Traffic Control Devices for Streets and Highways has no uniform guidelines for determining work zone speed limits. At their 1988 joint meeting, the AASHTO Highway Subcommittee on Traffic Engineering and the Maintenance Technical Committee of the National Committee on Uniform Traffic Control Devices unanimously concurred that research was urgently needed to establish a procedure for determining work zone speed limits to address safety problems. The research reported here was initiated to meet this need. The researchers sought to answer three fundamental questions: (1) Are work zones with reduced speed limits safer? (2) What are the compliance levels with various speed limit reductions? and (3) What roadway and traffic factors should be considered in determining a work zone speed limit? To answer these questions, Graham-Migletz Enterprises, Inc. (GME) conducted a literature review and interviewed state and local highway agency officials in 12 states to learn about the procedures their agencies used to establish work zone speed limits and the perceived effectiveness of various speed limit reduction policies. In addition, the research included interviews and surveys to determine the attitudes of motorists, construction contractors, and construction liability insurance carriers concerning how work zone speed limits should be set. The results were considered in planning field data collection on vehicle speeds, traffic accidents, and traffic conflicts in work zones. A candidate procedure for appropriate work zone speed limits was formulated early in the research and revised, as appropriate, throughout the remainder of the project. [More] | |
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191 - Management Guide for Implementation of Geographic Information Systems (GIS) in State DOTs
1/1/1993
The purpose of this Management Guide is (1) to provide a basic understanding of geographic information systems (GIS) and geographic information systems for transportation (GIS-T); (2) to describe the factors involved in successful planning and implementation of GIS-T; ( 3) to provide a basic understanding of how GIS-T can benefit transportation agencies; and (4) to describe benefit-cost considerations and methods for evaluating the success of GIS-T implementation. The work reported herein is intended to provide a basis on which individual transportation agencies can develop or revitalize--and then proceed with--plans to exploit GIS technology to the fullest in both the near-term and long-term futures. The Guide is organized in the following chapters: (1) Introduction; (2) Definition and Role of GIS-T; (3) Critical Success Factors; (4) Planning and Implementation Process; (5) Technical and Organizational Considerations; (6) System Justification and Evaluation; (7) Statewide Cooperative Efforts; and (8) Future Directions. A glossary is provided. [More] | |
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190 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1992
This staff digest reports on the progress and status of NCHRP Project 20-5, Synthesis of Information Related to Highway Problems, for which the Transportation Research Board is the agency conducting the research. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. Five tables are presented in this digest showing the following: (1) Completed Syntheses; (2) Topics Being Studied; (3) NCHRP Project Committee SP20-5 Members; (4) Synthesis Topics Selected for the FY 1993 Program; and (5) Index to Syntheses and Studies. [More] | |
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189 - Instrumentation for Measuring Scour at Bridge Piers and Abutments
1/1/1993
This Digest summarizes the findings from the Phase I final report under NCHRP Project 21-3, which was conducted by Resource Consultants, Inc. NCHRP Project 21-3 was initiated in 1989 to develop, test, and evaluate instrumentation that would be technically and economically feasible for use in monitoring and measuring maximum scour depth at bridge piers and abutments. The research is being conducted in three phases. Phase I ( FY '90), which identified and evaluated instruments, included some small-scale laboratory testing. Testing was done in indoor and outdoor flumes at the Hydraulics Laboratory at Colorado State University. Currently underway, Phase II (FY '92) will midify, improve, and field test the most promising techniques identified in Phase I. It is scheduled for completion in March 1994. Phase III will extend development and deployment of devices for remote scour monitoring. The following categories of devices were identified during Phase I as capable of measuring and monitoring the maximum depth of scour at bridge piers and abutments: (a) sounding rods, (b) sonar, (c) buried/ driven rods, and (d) other buried devices. [More] | |
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188 - Ultrasonic Nondestructive Testing for Deterioration of High-Strength Steel Components Embedded in Concrete
1/1/1992
This is a digest of the essential findings from the agency final report on NCHRP Project 10-30(3), Nondestructive Methods for Field Inspection of Embedded or Encased High-Strength Steel Rods and Cables, conducted by the Corrosion and Protection Centre Industrial Services (CAPSIS), University of Manchester Institute of Science and Technology, U.K. The project was initiated to develop a nondestructive testing method suitable for field inspection of bridges to detect serious deterioration of high-strength steel tendons or rods embedded in concrete. The case of posttensioned, prestressed concrete structures, with seven-wire strand steel tendons inside metal ducts, was regarded as a critical case to be addressed. [More] | |
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187 - Distribution of Wheel Loads on Highway Bridges
1/1/1992
This NCHRP digest presents the findings from NCHRP Project 12-26, Distribution of Wheel Loads on Highway Bridges. The project was initiated in the mid-1980s in order to develop comprehensive specification provisions for distribution of wheel loads in highway bridges. The study was performed in two phases: Phase I concentrated on beam-and-slab and box girder bridges; Phase II concentrated on slab, multibox beam, and spread box beam bridges. Three levels of analysis were considered for each bridge type. The most accurate level, level 3, involves detailed modeling of the bridge deck. Level 2 includes either graphical methods, nomographs and influence surfaces, or simplified computer programs. Level 1 methods provide simple formulas to predict lateral load distribution, using a wheel load distribution factor applied to a truck wheel line to obtain the longitudinal response of a single girder. The formulas developed in this study for the level 1 analysis were based on the standard AASHTO HS truck. Levels 2 and 3 analyses may be applied for trucks outside the AASHTO family of trucks. The major part of this research was devoted to the level 1 analysis methods because of its ease of application, established use, and the surprisingly good correlation with the higher levels of analysis in their application to a majority of bridges. [More] | |
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186 - Data Interchange Standards for Bridge Management Systems and Integrated Highway Information Systems
1/1/1992
This digest provides a summary of existing and emerging standards for data interchange that might be adapted to bridge and other infrastructure management systems, and contains a brief account of what might constitute a universal standard. The material for this digest was developed under NCHRP Project 20-7, Task 46, AASHTO Guidelines for Bridge Management Systems, conducted by The Urban Institute, Mr. William A. Hyman, Principal Investigator. [More] | |
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185 - NCHRP Supports Advances in Differential GPS Satellite Surveying
1/1/1992
This Digest is a status report on National Cooperative Highway Research Program (NCHRP) Project 20-23, Kinematic Differential GPS Satellite Surveying. Although the Global Positioning System (GPS) is a satellite system being developed by the Department of Defense, some civilian applications are allowed. Presently, 15 satellites providing positioning information are in orbit. An 18-satellite constellation providing 24-hour coverage is expected to be fully operational in late 1993. This research has resulted in a technique by which highway engineers and surveyors may rapidly obtain precise positions necessary to maintain geodetic control. The technique uses measurements of the GPS, commercially available GPS receivers, and personal computers for data processing. Users of this technique need to occupy each point to be surveyed for only one or two minutes, thus providing an efficient means to quickly and precisely survey a large number of points. Horizontal accuracies of one centimeter and vertical accuracies of three centimeters have been demonstrated. The software has been written to run on most available personal computers and can be operated with no special skills required. NCHRP Project 20-23 is essentially completed; however, the finalized research reports are still pending. [More] | |
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184 - NCHRP Research on Pavements
1/1/1992
This Digest outlines the status of all National Cooperative Highway Research Program (NCHRP) research related to highway pavements. Most NCHRP research in this area focuses on design, materials, construction, evaluation, and management of pavements. This information is provided in five tables. Table 1 concerns research is progress. Table 2 provides information on pending research. Tables 3, 4 and 5 list, respectively, NCHRP publications, agency final reports, and agency final reports receiving special treatment. [More] | |
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183 - Administration of Highway and Transportation Agencies Project 20-24 Series
1/1/1992
This Digest reports on the progress of projects emanating from Project 20-24, "Administration of Highway and Transportation Agencies". To date ten projects have been initiated. Four of these have been completed and the others are in progress. A table is included showing the following: Project Number; Title; Research Agency; Contract Amount; Start Date; Completion Date; and Project Status. [More] | |
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182 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1991
This staff digest reports on the progress and status of NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems," for which the Transportation Research Board is the agency conducting the research. This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This digest describes the synthesis program and summarizes progress to date in the following tables: (1) Completed Syntheses; (2) Topics Being Studied; (3) NCHRP Project Committee SP20-5 Members; (4) Synthesis Topics Selected for the FY 1992 Program; and (5) Index to Syntheses and Studies in Progress. [More] | |
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181 - Video Image Processing for Evaluating Pavement Surface Distress
1/1/1991
This digest presents the findings from the final report on NCHRP Project 1-27, which was conducted by Triple Vision, Inc., Dr. R.A. Fundakowski, Principal Investigator. The objective of NCHRP Project 1- 27 was to develop a system for processing video images to identify, quantify, and classify pavement distress in terms of types, severity, and extent. [More] | |
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180 - Implementation of Geographic Information Systems (GIS) in State DOTs
1/1/1991
This digest presents the essential findings from the interim report on NCHRP Project 20-27, Adaptation of Geographic Information Systems for Transportation, by A. Vonderohe, L. Travis, and R. Smith, University of Wisconsin, Madison. Geographic Information Systems (GIS) offer the potential to assemble and process data from a diversity of sources and present it in an easily understood graphical format. The capabilities of a GIS in the transportation field (GIS-T) will permit the assimilation, integration, and presentation of data collected and stored by each of the divisions within a highway agency. The materials presented in this digest provide (1) a 1990-1991 snapshot of the GIS-T implementation status in the U.S., (2) a description of feasible applications, (3) a review of technological and institutional issues that are faced in implementing GIS-T, and (4) an outline of critical factors that must be considered. [More] | |
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179 - Financing Highway Improvements Through Public and Private Partnerships
1/1/1991
This digest presents the findings from NCHRP Project 2-14, "Public/ Private Partnerships for Financing Highway Improvements," which was conducted by Kimley-Horn and Associates. The overall objective of the research project was to provide guidance to state and local highway officials, and to private developers, on existing and potential public- private partnership mechanisms, including present statutes and ordinances related to private participation in financing highway improvements. [More] | |
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177 - NCHRP Research on Maintenance Engineering
1/1/1990
This digest summarizes the progress and status of maintenance engineering research under the National Cooperative Highway Research Program (NCHRP). Five tables are included which list the following: Research in Progress; Pending Research; Available NCHRP Series Publications; Uncorrected Agency Final Reports; and Agency Final Reports Receiving Special Treatment. [More] | |
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176 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1990
This staff digest reports the progress and status of NCHRP Project 20- 5, Synthesis of Information Related to Highway Problems. There are five tables containing the following: (1) Syntheses of Highway Practice that have been completed under this project and Research Results Digests on topics studied under this project; (2) Topics currently being studied; (3) Membership of NCHRP Project Committee SP20-5; (4) Synthesis topics selected for the FY 1991 Program; and (5) An index to published syntheses and topics under study, as well as those expected to be started through 1991. [More] | |
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175 - NCHRP Research on Construction Engineering
1/1/1990
This digest summarizes the progress and status of construction engineering research under the National Cooperative Highway Research Program (NCHRP). Five tables are included which list the following: Research in Progress; Pending Research; Available NCHRP Series Publications; Uncorrected Agency Final Reports; and Agency Final Reports Receiving Special Treatment. [More] | |
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174 - Determination of Water:Cement Ratio in Fresh Concrete
1/1/1990
This digest presents the essential findings from NCHRP Project 10-25A, Instantaneous Determination of Water-Cement Ratio in Fresh Concrete. The objective of the research was to develop a method of measuring the water:cement ratio in concrete that could form the basis of an acceptance test at the job site. An extensive literature search did not reveal any successful development of a probe, but did suggest the use of a specific ion electrode that would selectively determine the concentration of a water-soluble constituent of the portland cement in the mix water of the concrete. After extensive efforts, however, the specific ion electrode approach was abandoned. Other approaches that were simultaneously investigated yielded two methods for water and one for cement that offer promise. They were developed to the stage where each appears to be equal to or better than any others now available. A brief description of each method is included in this digest. They are: (1) a cement content procedure employing a colorimetric method to determine silica content of cement; (2) a water content procedure employing a microwave oven to determine moisture content of samples; and (3) a water content procedure employing a bromide solution addition to the concrete sample to determine the amount of dilution by the mix water. [More] | |
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173 - Guidelines for Establishing Executive Management Information Systems for State Departments of Transportation
1/1/1990
This digest presents the essential findings from the final report on NCHRP Project 20-24(2), Executive Management Information Systems for State Departments of Transportation. The overall objective was to provide the executive accurate, timely, relevant, and accountable information to measure the accomplishments and status of the department. Specific objectives were to (1) develop a prototype to assist DOT executives in understanding what an Executive Management Information System (EMIS) can do for state DOTs, and (2) outline the step-by-step process that would be needed to design, implement, and support an EMIS. These objectives were accomplished through the following activities: Executive information requirements were determined through interviews and questionnaires; An EMIS prototype was developed and revised based on interview comments; Information requirements were analyzed, producing a matrix describing the relationship of executive requests and the department's base systems; EMIS software and hardware alternatives were identified and evaluated; and EMIS design and implementation guidelines were drafted. This digest presents the findings of the interviews and research performed for this project, the applications and benefits of an EMIS, and the conclusions reached. [More] | |
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172 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1990
The American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program (NCHRP), authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. The Syntheses of Highway Practice that have been completed under this project are listed in Table 1 of this Digest, along with 2 Research Results Digests on topics studied under the project. Work currently underway is listed in Table 2. NCHRP Committee SP20-5 meets each Fall to select topics for study using funds from the upcoming fiscal year. The membership of this committee is given in Table 3. Topics selected for the current program are listed in Table 4. Table 5 contains an index to published syntheses and topics now under study, as well as those expected to be started through 1990. Also included are corrections to errors in published Syntheses 118, 138, 140, 144 and 147. [More] | |
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171 - Pot Bearings and PTFE Surfaces
1/1/1989
This digest provides a summary of the pot bearing synthesis that was performed in Phase III of NCHRP Project 10-20, Elastomeric Bearings Design, Construction, and Materials. Phase III concerned low temperature bearing behavior and prequalifications and acceptance testing. Pot bearings and bearings with PTFE (polytetrafluorethylene) sliding surfaces are widely used in bridge construction. They support heavy compressive loads while permitting large movements or rotations. Despite their wide use, they are typically designed and constructed on a highly empirical foundation based on guidelines proposed by the manufacturer. Present practice in the United States and abroad was examined in some detail. European experience is included because it is frequently longer than that noted in the U.S. The discussion of pot bearings includes structural behavior, design, materials, fabrication and installation, and certification test methods. For PTFE sliding surfaces, the discussion covers applications, material properties, design, installation and fabrication of bearings with PTFE, and certification methods. [More] | |
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170 - Research Program Design Administration of Highway and Transportation Agencies
1/1/1989
Much of the research conducted by the NCHRP is designed to solve specific problems, experienced by practitioners, that are related to the operational and planning functions of state highway departments. Although top management is certainly affected by these problems and benefits from solutions through improved agency performance, this type of research does not necessarily address top management's most immediate needs. A research program designed from the perspective of top management would help provide a needed resource to support the decisions and improve the effectiveness of top managers. Such a program has been initiated under NCHRP Project 20-24. This Digest presents summaries of proposed projects in resource development, decision support, and financial management. The three current projects in the NCHRP Project 20-24 Series are: (1) Using Market Research to Improve Management of Transportation Systems; (2) Executive Management Information Systems for State Departments of Transportation; and (3) Recruitment, Training, and Retention of Professional Employees. [More] | |
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169 - Rapid Replacement of Portland Cement Concrete Pavement Segments
1/1/1989
The objectives of this study were to identify, describe, and evaluate methods that have been, and are being, used for rapid replacement of full lane-width segments of both continuously reinforced and jointed portland cement concrete (PCC) pavements relative to costs, placement conditions, traffic characteristics, performance, and expected service lives. The research has accomplished these objectives and the results have been documented in the agency final report. Useful results were achieved and are reported in this Digest to provide adequate circulation of the outcome of the research. [More] | |
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168 - Continuing Project to Synthesize Information On Highway Problems (Superseded)
1/1/1988
The American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program (NCHRP), authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. The Syntheses of Highway Practice that have been completed under this project are listed in Table 1 of this Digest, along with 2 Research Results Digests on topics studied under the project. Work currently underway is listed in Table 2. NCHRP Committee SP20-5 meets each Fall to select topics for study using funds from the upcoming fiscal year. The membership of this committee is given in Table 3. Topics selected for the current porgram are listed in Table 4. Table 5 contains an index to published syntheses and topics now under study, as well as those expected to be started through 1989. The National Cooperative Transit Research and Development Program (NCTRP) has a separately funded project that produces syntheses of transit practice similar to the highway syntheses produced under NCHRP Project 20-5. Table 6 lists the transit syntheses that have been published to date, as well as those topics that are being studied. [More] | |
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167 - NCHRP Research On Bridge Engineering
1/1/1988
This Digest supersedes NCHRP Research Results Digest 155 published in February 1986. The purpose of the Digest is to outline for easy reference (in Tables 1 through 5) the status of, and inter- relationships between, all NCHRP research related to bridges. Included are projects under development, in progress, and completed. A listing of all related research reports is also provided. [More] | |
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166 - Continuing Project to Synthesize Information On Highway Problems (Superseded)
1/1/1987
There exists a vast storehouse of information relating to nearly every subject of concern to highway administrators and engineers. Much of it resulted from research and much from successful application of the ideas of practitioners faced with problems in their day-to-day work. The American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. This staff digest reports on the progress and status of NCHRP Project 20-5. Table 1 lists the Syntheses of Highway Practice that have been completed under this project. Two Research Results Digests on topics studied under the project are also listed. Work is currently under way on the topics listed in Table 2. NCHRP Project Committee SP20-5 meets each Fall to select topics for study using funds from the upcoming fiscal year. The membership of this committee is given in Table 3. Topics selected for the current program are listed in Table 4. Table 5 contains an index to published syntheses and topics now under study, as well as those expected to be started through 1988. [More] | |
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165 - Legal Techniques For Reserving Right-of-Way For Future Projects Including Corridor Protection
1/1/1987
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of specific problems in highway law. This report presents a general outline of highway reservation laws, discusses the constitutionality of related legal techniques, and describes some of the associated NEPA ( National Environmental Policy Act) problems. This paper was prepared under NCHRP Project 20-6, Legal Problems Arising Out of Highway Programs, for which the Transportation Research Board is the Agency conducting the research. The contents are as follows: Introduction; The Taking of Property Problem in Highway Reservation Laws; A General Outline of Taking Law; The Constitutionality of Legal Techniques for Reserving Right of Way; Problems Under the National Environmental Policy Act; Some Guidelines for Drafting Highway Reservation Laws; Appendix A: Model Laws for City and County Official Map Acts; Appendix B: State Enabling Legislation for City and County Official Map Acts; Appendix C: State Highway Reservation Laws; and Footnotes. [More] | |
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164 - Rights Abutting Property Owner Upon Conversion of Uncontrolled-Access Road Into Limited-Access Highway
1/1/1987
This paper deals with the rights of a landowner whose property abuts on a conventional road that is converted into a limited-access highway. In the typical situation prior to the conversion the owner has direct access to the adjoining unlimited access highway and after the conversion his means of ingress to and egress from the new controlled- access highway is limited either to travel along a frontage road that has a point or points of connection with the new highway, or, in the event his property abuts on another existing public road, he is relegated to travel along such road to a point where it connects directly, or through other roads in the public highway system, with the new highway. In either case his travel is circuitous when compared to his former right of direct access. The question is whether he is entitled to damages for the impairment of his former right of direct access. The question is basically one of the adequacy of substitute access. And the answer is that if the substitute access is reasonably adequate, the owner is not entitled to compensation, but if the substitute access is not reasonably adequate, or constitutes a material or substantial impairment of the former right of access, the owner is entitled to compensation. Significant cases, the majority of which were decided in the period immediately following the enactment of the law creating the Interstate System, are reviewed and the measure and elements of damage where compensation is required are considered. [More] | |
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163 - Supplement to Competitive Bidding and Award of Construction Contracts in Selected Studies in Highway Law
1/1/1987
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of specific problems in highway law. This report supplements and updates a section in Volume 3 of Selected Studies in Highway Law, published by the Transportation Research Board, dealing with the competitive bidding process used for transportation projects. An overview of federal and state legal requirements is provided, along with a discussion of the various steps in the process. [More] | |
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162 - Continuing Project on Legal Problems Arising Out of Highway Programs (Superseded)
1/1/1987
The National Cooperative Highway Research Program Project 20-6, established to meet the need for the analysis and evaluation of operatiing practices and legal issues associated with highway projects is described. Part of the products of this Project (20-6 ) is the 4- volume "Selected Studies in Highway Law." The contents of these volumes are listed in this digest. Published papers from this study are also distributed through the NCHRP Research Results Digest series. New topics of current interest will continue to be researched, and the text will continue to be updated and supplemented. Topics currently approved for research but not yet completed are listed. [More] | |
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161 - Public and Private Partnerships for Financing Highway Improvements
1/1/1987
This report addresses the legal considerations related to alternative funding mechanisms being used for highway improvements. It focuses on the various approaches being used by different states and local agencies to develop funding strategies involving both the public and private sector, and the legal basis for each approach. The paper consists of 4 sections. The first section provides an introduction to legal doctrine related to each of the approaches. The second considers both tradiitional and non traditional special assessments. The third section addresses subdivision exactions and recently developed impact fees. The final section discusses contract and conditional zoning and development agreements. The text provides supporting citations in extensive footnotes. [More] | |
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160 - Acquisition of Uneconomic Remnants Under 23 U.S.C. 109(f)
1/1/1987
This report addresses the conflict between the provisions of 23 U.S.C. 109(f) and the terms of 42 U.S.C. 4651(9) as they relate to the purchase of uneconomic remnants of land involving Federal participation. An uneconomic remnant is defined as: A remaining part of land, after a partial acquisition, that is of little or no utility or value to the owner. This research should prove helpful to highway and transportation administrators, their legal counsel, right-of-way officials, federal administrators, and others involved in the purchase of right-of-way and the defense of the state in lawsuits regarding partial acquisitions. The author's opinion on the resolution of the apparent conflict between the two provisions of the U.S. Code, based on a review of the case law, should provide useful guidance in future cases. [More] | |
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159 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1986
This publication reports on a continuing study, "Synthesis of Information Related to Highway Problems," which searches out and synthesizes useful knowledge from all possible sources and prepares documented reports on current practices in the subject areas of concern. Reports from this effort constitute the National Cooperative Highway Research Program's series, "Synthesis of Highway Practice." Each synthesis is an immediately useful document that records practices that were acceptable within the limitations of the knowledge available at the time of its preparation. The Syntheses of Highway Practice that have been completed under this project are listed, as well as topics currently being studied. Topics that have been selected for study in FY 1986 are also listed. [More] | |
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158 - Legal and Procedural Issues Related to Relocation Assistance
1/1/1986
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems in highway law. This report deals with the legal and procedural issues that public officials face in administering relocation assistance programs for the acquisition of land for transportation projects. A comprehensive analysis of these issues is provided. This paper will be included in a future addendum to " Selected Studies in Highway Law," published by the Transportation Research Board. [More] | |
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157 - Supplement to Licensing and Qualification of Bidders in Selected Studies in Highway Law
1/1/1986
This report supplements and updates a section in Volume 3 of "Selected Studies in Highway Law" dealing with licensing and qualification of public works contractors. The report gives an overview of state legislation, and describes prequalification policies and procedures, and suspension and revocation procedures. Statutory structure and the scope of the licensing requirement are examined and a table summarizes the licensing requirements in the State of New Mexico. State practice regarding prequalification of bidders on highway construction contracts is covered, and a summary of state laws and regulations relating to qualification of bidders is tabulated. The report also covers the appeal and review of adverse actions, and the prequalification and certification of disadvantaged business enterprises. [More] | |
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156 - Continuing Project on Legal Problems Arising Out of Highway Programs (Superseded)
1/1/1986
The National Cooperative Highway Research Program (NCHRP) Project 20-6 was established to meet a continuing need for analysis and evaluation of operating practices and legal issues associated with highway projects. The project also compares individual state practices for possible national application. As part of this project, the Transportation Research Board introduced "Selected Studies in Highway Law" (SSHL) which covers many branches of the law including contracts, torts, eminent domain, evidence, and taxation. SSHL fills a void in American legal literature by furnishing a rerference that is directly and exclusively concerned with highway law. SSHL provides a compilation of cases dealing with highways and is a clearinghouse for analysis and discussion of the rules of law annouced therein. This report briefly notes the content of various volumes of SSHL. The report also tabulates NCHRP Research Results Digests emanating from Project 20- 6. It also lists topics approved for study as well as Project Committee members. [More] | |
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155 - NCHRP Research on Bridge Engineering (Superseded)
1/1/1986
The purpose of this Research Results Digest is to outline for easy reference the status of all NCHRP research related to bridges. Included are projects completed, in progress, and under development. A listing of all related research reports is also provided, with directions for obtaining copies. This digest supersedes RRD 143 published in February 1984. (Author) [More] | |
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154 - Trial Strategy and Techniques in Enforcing Laws Relating to Truck Weights and Sizes
1/1/1986
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems in highway law. This report deals with the enforcement of load limit violations by overweight trucks through relief against the persons or corporations who load or unload the vehicles as well as the truck operators. [More] | |
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152 - Enforceability of the Requirement of Notice in Highway Construction Contracts
1/1/1986
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems of highway law. This report deals with highway construction contractor claims for compensation beyond the original contract amount and the requirements for advance notification of such claims. [More] | |
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149 - Exaction of Right-of-Way by Exercise of Police Power
1/1/1986
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems in highway law. This report deals with the legal issues related to exactions, i.e., the compulsory dedication of private property for a public use without payment of compensation. Illustrative test cases are described related to the exaction of highway right-of-way. [More] | |
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148 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1985
The American Association of State Highway and Transportation officials, through the Natural Cooperatives Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP 20- 5 "Synthesis of Information Related to Highway Problems" to search out and Synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. The report series "Synthesis of Highway Practice" assembles the various forms of information into single concise documents pertaining to highway problems or sets of closely related problems. Information from numerous sources including State highway and transportation departments are analyzed and a panel of experts guides researchers in organizing and evaluating the data and reviewing the report. The Syntheses that have been published are tabulated. The topics on which work is currently under way are also tabulated. This present publication also explains the process for submision and selection of topics and the conduct of the studies. An index to published syntheses topics now under study is included. [More] | |
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147 - Mineral Rights in Rights-of-Way: Acquisition, Valuation, and Disposition
1/1/1985
This report addresses three specific issues related to the acquisition and ownership of highway rights of way: the status of the title acquired by the highway agency, valuation of mineral lands, and disposal methods for minerals underlying highway rights of way. The paper explores several valuation questions that have plagued courts and describes the recent cases that may indicate a trend toward liberalization of the rules regarding the evidence admissible on the valuation of mineral lands under condemnation. The paper also describes some of the issues and answers and gives practical suggestions for dealing with the problems associated with the leasing of oil and gas. This report, prepared under ongoing NCHRP Project 20- 6, "Legal Problems Arising Out of Highway Programs," will be included in a future addendum to a 3-volume text entitled "Selected Studies in Highway Law". [More] | |
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146 - Minority and Disadvantaged Business Enterprise Requirements in Public Contracting
1/1/1985
This paper deals with the history and development of the minority and women business enterprise programs in public contracting and reviews the treatment these programs have received in the courts including an extensive discussion of the United States Supreme Court regarding affirmative action. It concludes with a practical discussion regarding the certification process in dealing with potential fronts and appeals regarding certifications. [More] | |
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145 - First Amendment Aspects of Control of Outdoor Advertising
1/1/1985
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems in highway law. This report deals with the significance of a recent court decision, Metromedia, Inc. vs. City of San Diego, regarding the First Amendment guarantee of free speech when applied to control of outdoor advertising. (Author) [More] | |
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144 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1984
The American Association of State Highway and Transportation Officials has, through the mechanism of the National Cooperative Highway Research Program, authorized the Transportation Research Board to undertake a continuing study, NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems." This study is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice, that collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. The 117 Syntheses of Highway Practice that have been completed are tabulated as are also the 26 topics currently being researched. The membership of the NCHRP Project Committee SP20-5 which selects the study topics are also listed. A table of topics selected for the FY '85 program is included. [More] | |
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143 - NCHRP Research on Bridge Engineering
1/1/1984
The purpose of this Research Results Digest is to outline for easy reference the status of all NCHRP research related to bridges. Included are projects completed, in progress, and under development. A listing of all related research reports is also provided, with directions for obtaining copies. This digest supersedes RRD 132 published in May 1982. (Author) [More] | |
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142 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1983
The NCHRP (National Cooperative Highway Research Program) Project 20-5 " Synthesis of Information Related to Highway Problems" attempts to search synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. The reports from this project constitute a report series, " Synthesis of Highway Practice", which assembles the information into simple concise documents pertaining to specific highway problems. The series also makes specific recommendations where appropriate but without detailed directions. The 107 published Syntheses of Highway Practice are listed in this pamphlet. The pamphlet also describes the submission and selection of topics for synthesis preparation, and the conduct of the studies. The pamphlet also includes an index to the published syntheses and topics now under study. [More] | |
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140 - Development of a New Highway Capacity Manual: Status Report (Superseded)
1/1/1983
A status report is provided on the research that is being directed to the development of a new Highway Capacity Manual. This research is being conducted by NCHRP (National Cooperative Highway Research Program), FHWA (Federal Highway Administration), the TRB ( Transportation Research Board) Committee on Highway Capacity and Quality of Service (A3A10), and others. The NCHRP project is a multiphase effort with the overall objective of providing the basis for a revision of the 1965 Manual. The objectives of the first phase of the study. NCHRP and FHWA projects are briefly reviewed and the content of the new manual is summarized. [More] | |
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139 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1983
This staff digest of the current progress and status of NCHRP Project 20-5, "Synthesis of Information Related to Highway Problems", lists 100 published Synthesis of Highway Practice prepared under this project to date; two Research Results Digests on topics studied under the project; 23 topics currently being studied; and 18 topics selected for FY '83. All synthesis topics, whether published, currently under study, or proposed, are listed together in an alphabetical index. [More] | |
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133 - Evaluation of Winter-Driving Traction Aids
1/1/1982
A set of test procedures has been selected to measure the braking, driving traction, and controllability of (1) vehicles fitted with tires and tire-associated traction aids intended to increase available friction on ice and snow surfaces and (2) vehicles fitted with drive- train aids intended to make better use of available friction. The performance of traction-aids intended to increase available friction, such as tire chains, snow tires, studded tires, and improved rubber compounds, may be determined from a combination of the following test data: 1. Locked-wheel braking friction or locked-wheel stopping distance at a speed of 20 mph (32.4 km/hr). 2. Spinning driving traction at a vehicle speed of 5 mph (8.1 km/hr) with the traction force measured at a slip ratio greater than 1. 3. Spinning driving traction with the test vehicle stationary and tire slip speed greater than 10 mph (16.2 km/hr); and 4. Limiting (minimum) lateral tire force measured with a single-wheel tester. The standardized test procedures for obtaining the test data are described in the report. The performance of traction-aids intended to make better use of available friction, such as the limited slip differential, nonlocking brakes, and the four-wheel drive, may often be calculated directly from the relevant vehicle characteristics and an assumed tire/friction factor. A simulation program was written and used to study the controllability performance of vehicles fitted with these aids. (Author) [More] | |
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131 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1982
This staff digest of the progress and states of NCHRP Project 20-5, " Synthesis of Information Related to Highway Problems," lists 88 published Syntheses of Highway Practice that have been prepared under this project to date, two Research Results Digests on topics studied under the project, 23 topics currently being studied, and 21 synthesis topics for the FY '82 program, along with an index of topic subjects. [More] | |
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130 - Variability in Temperature Susceptibility of Asphalt Concrete
1/1/1981
Temperature susceptibility of asphalt cement is an important control parameter during the mixing, placing, compaction, and performance of asphaltic concrete. Early methods of measuring this characteristic involved the use of needle penetration devices. Viscosity began to appear in specifications in the 1920's. Today's specifications often make use of viscosity and penetration measurements at 140 F and 275 F both before and after laboratory aging. Recent testing equipment developments have made low temperature (20 F) viscosity measurements possible, adding to the ability to determine temperature susceptibility of asphalt cements. There does not appear to be one generally accepted measurement method for this particular characteristic of asphalts; however, the report describes several methods that have been used. The primary task of the study--to collect and analyze temperature susceptibility data--was accomplished by (1) the review and summarization of data from several published reports by such agencies as The Pennsylvania State University, the Federal Highway Administration, the Asphalt Institute, and several states; and (2) the laboratory testing of selected asphalt cements from individual refineries and field construction projects. The published literature indicates that the physical properties, including temperature susceptibility, of asphalt cements produced in recent years have the same range of values as those produced in 1964 and during the 1965-1973 preembargo period. Mean values and their distributions for particular physical and chemical properties have varied over the years on a national and regional basis. However, the published literature contains little information on relationships between the variations in asphalt cement properties and pavement construction and performance problems. Detailed asphalt test data were obtained from 5 states representing 23 refineries in all regions of the United States. A statistical analysis of the data indicates a significant variability with time of temperature susceptibility of the asphalts. This does not imply that the temperature susceptibility varied to such an extent that pavement construction and performance were affected. [More] | |
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128 - Continuing Project on Highway Right-of-Way and Legal Problems
1/1/1980
This digest reports the progress and status of NCHRP Project 20-6. It contains a list of the digests emanating from this project and presents the contents of Volumes 1, 2 and 3 of the TRB special publication, Selected Studies in Highway Law. Topics selected for study under this project but not yet completed are also listed. [More] | |
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127 - The Vehicle-Miles of Travel -- Urban Highway Supply Relationship
1/1/1980
The objective of this research was to determine whether a relationship exists between measures describing urban highway supply and VMT and, if so, to quantify the relationships. Furthermore, highway supply measures were to be related to air pollution rates and fuel consumption through the use of known VMT/air pollution/fuel consumption relationships. To be useful to practitioners, the relationships were to be generalized and in the form of tables, graphs, and monographs. The review of previous research and the analysis process carried out in this project have led to the conclusion that there is a relationship between urban highway supply and vehicle-miles of travel (VMT). Although this conclusion is not unanimous among previous analysts of the topic, many previous studies point to this relationship. The work reported here shows that when urban travel is simulated using a detailed set of empirical models, validated against observed data, VMT changes do occur as highway supply changes are specified. Even when the total VMT change in a large urban area is predicted to be insignificant, its variations by location, type of highway facility, and highway speed result in much more significant changes in a wide range of VMT-related impacts: mobility, quality of travel service, air quality, fuel consumption, and safety. (Author) [More] | |
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126 - Performance Evaluation of Signalized Network Control Strategies
1/1/1980
This digest presents the findings from the final report on NCHRP Project 3-18(4). This Project had the objective of developing a methodology that would enable traffic engineers to select the most appropriate network performance measure of effectiveness (MOE) and to quantify that MOE using efficient, simple, and inexpensive data collection techniques. [More] | |
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125 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1980
This digest reports the progress and status of NCHRP Project 20-5. The 73 published Syntheses of Highway Practice that have been prepared under this project are listed, along with two other Digests. The 29 topics currently being studied under this project are also listed, followed by those topics selected for the FY 81 program. Finally, an index to published syntheses and topics now under study, as well as those expected to be started through 1981, is presented. [More] | |
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124 - A Modified Foundation for Breakaway Cable Terminals (Superseded)
1/1/1980
This digest recommends a modification to the foundation detail for the timber post version of the breakaway cable terminals (BCT), and reemphasizes a feature of the BCT which has been shown by accident experience to be crucial to proper performance. Questions which this research study attempted to answer are; how can the cost of the concrete footings for the breakaway posts be reduced; how can removal of broken timber posts from the concrete footings be facilitated; how can the guardrail BCT be adapted for use where site conditions do not allow the 4-ft glove specified in the recommended design? The foundation detail developed by the Illinois Department of Transportation is described. This project included a limited study of the anchor strenghth of this detail. Dynamic tests were conducted and detail was modified to produce acceptable test results. The test procedures and results are summarized. The installation of the BCT is illustrated with diagrams and alternative foundation systems are described. [More] | |
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123 - Evaluation of Performed Elastomeric Joint Sealing Systems
1/1/1980
This digest presents the findings from the final report on NCHRP Project 4-9. The project achieved the objective of developing guide specifications for preformed elastomeric seals. These specifications are presented in the appendix of this digest. [More] | |
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122 - Noise Barrier Acoustical Parameters -- Experimental Results
1/1/1980
This study attempted to determine those factors which would help improve existing noise barrier prediction models such as included in FHWA's "Noise barrier design handbook" and NCHRP Report 74, "Highway Noise--A design guide for prediction and control." Three specific aspects of the models were investigated: (1) the effects of ground absorption; (2) the relative effects of different cross- sectional shapes, and (3) the barrier surface absorption properties Laboratory Tests (summarized in this digest) were conducted to validate the theoretical findings of the first phase of this study reported in Research Results Digest 105. It is noted that the main area for improvement in current manuals is in the manner of dealing with terrain attenuation, both with and without barrier present. Insertion loss predictions and aspects of ground reflection phenomena are also discussed. Differences in barrier cross-sectional geometry do not significantly affect performance of common barrier configurations beyond the effects already accounted for in the models. Absorptive surfaces on barriers slightly improve barrier effectiveness. Absorptive coverings of highway barriers are treated fairly thoroughly in the final report of this project. [More] | |
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121 - Development and Field Evaluation of Prototype Soil Moisture Sensors
1/1/1980
This paper discusses a study where moisture determinations from nuclear magnetic resonance (NMR) and dielectric sensors were compared with moisture measurements obtained by nuclear depth probes and gravimetric analysis of soil borings. The following are general observations and conclusions of the field evaluation phase of the study: some operational problems were encountered with several sensors of each type; with suitable calibration, both sensors are capable of determining in situ moisture content with an estimated accuracy of 2 percent; although the actual moisture levels encountered in the field were only in the 20 to 30 percent range, on the base of the results of laboratory tests, the actual operating range of the sensors is estimated to be 0 to 50 percent; best results are obtained by calibrating the sensors using the soils of interest; special installation procedures devised for the sensors produce minimal disturbance of the subgrade soil; laboratory studies of temperature effects showed that the dielectric sensor can be used to determine with a high degree of certainty when freezing of pore fluid occurs; and on the basis of current fabrication costs, the price to the user for production quantities is estimated to be $125 per sensor, $1,000 for the dielectric readout, and $5,000 for the NMR readout. The results of this research indicate that both the dielectric and the NMR measurement systems can be potentially useful for in situ determination of moisture in pavement subgrades; and with proper calibration, the accuracy of moisture measurement with these sensors can be at least comparable to existing in situ sensor types such as moisture blocks. [More] | |
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120 - Residential Dislocation -- Costs and Consequences
1/1/1980
Research was conducted to develop techniques for predicting dislocation consequences of alternate route and design proposals and to identify related legislative or regulatory constraints and recommend modifications to ensure equity to the displacees. This digest presents recommendations for changes in compensation, in relocation practices and in the highway planning process. Recommendations to modify existing legislation or regulations were largely found to be unnecessary. [More] | |
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118 - NCHRP Research on Bridge Engineering
1/1/1980
This digest outlines the status of all NCHRP research related to bridges and includes projects which are completed, in progress, and under development. A listing of all related research reports are also provided with directions for obtaining copies. Tables are provided which chronologically list all NCHRP publications of bridge research including the NCHRP Report series, the NCHRP Synthesis of Highway Practice, and the NCHRP Research Results Digests on studies related to bridges. [More] | |
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117 - Guidelines for Selecting Traffic Signal Control at Individual Intersections
1/1/1980
An NCHRP Project 3-27 comprehensive guidelines were developed to help traffic engineers evaluate the costs and benefits of various control alternatives while taking roadway and traffic conditions into account. Although the emphasis was on traffic control at isolated intersections, adjacent intersections were considered in regard to the need for coordinated operation. This digest discusses the approach used and gives the findings and conclusions of the study. Graphs are presented giving a comparison of controller performance in terms of delay per vehicle and percent stops per vehicle. [More] | |
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115 - NCHRP Research on the Durability of Reinforced Concrete Bridge Components
1/1/1979
Numerous studies on the durability of reinforced concrete bridge components have been included in the National Cooperative Highway Research Program (NCHRP). In recent years, concurrently with a growing national awareness of bridge deterioration, a substantial number of research projects on this problem have been referred to NCHRP by the program sponsors, the American Association of State Highway and Transportation Officials (AASHTO). The purpose of this Digest is to outline the status of this research for easy reference. Information is included on all projects either completed or in progress (Table 1). All relevant NCHRP publications are listed, (as well as some unpublished reports) with directions for obtaining copies. /Author/ [More] | |
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114 - Energy Analysis Methodology for Assessing Environmental Impacts
1/1/1979
Several years of developmental research have contributed to the evolution of an energy analysis methodology to assess the environmental impacts of transportation facilities. Recent energy analysis research projects and case study applications have indicated that the methodology may offer significant improvements to the environmental analyses used to assess the impacts of transportation facilties and operations. NCHRP Project 20-11B was therefore established to develop an applications manual that succinctly describes the theories, tools, procedures, and data sources necessary for applying the energy analysis methodology. The project has succeeded in this regard and, through explicit descriptions of energy analysis procedures and identification of their range of applicability in the transportation field, the states have available to them a manual that will provide a better understanding of the methodology and facilitate its use. In the manual developed in NCHRP Project 20-11B, energy is used as the common measure. It is used in a procedure to quantitatively evaluate the effect on human-system processes of environmental impacts due to transportation actions. Comparable energy accounts are evaluated for a variety of individual impacts to the natural environment. The energy analyses follow the laws of thermodynamics to evaluate the minimal energy cost of replacing natural-environment goods and services that may be stressed by transportation actions. The severity of different kinds of environmental impacts may be compared according to those energy costs. In addition, knowing energy use/dollar correlations for a given economy, the energy costs may be translated into money costs. By having evaluated the various free work contributions from the natural environment, the analysis shows how much the individual or aggregated environmental impacts may change the total effectiveness of transportation investments. /Author/ [More] | |
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109 - Control of Conflicts of Interest in Highway Construction Contract Administration
1/1/1979
State highway departments and transportation agencies have a continuing need to keep abreast of operating practices and legal elements of special problems involving contracts, as well as highway law in general. This report deals with legal questions surrounding conflicts of interest involving public officials. An extensive body of law has been developed to control or prevent conflicts of interest in public transactions. From common law origins dealing chiefly with bribery of judical officers and employees, state legislation has extended the scope of these laws to reach all types of governmental functions and classes of public officers and employees, and has enlarged their purpose to include prevention as well as punishment of unlawful conflicts. Much of the present body of conflict of interest law applicable to the award and administration of highway contracts is in response to numerous investigations by executive and legislative bodies, including a thorough inquiry by the House Special Subcommittee into the Federal Aid Highway Program. Use of administrative power and procedures added flexibility to the enforcement of conflict of interest rules and paved the way to the most recent developments in this body of law, namely: enactment of codes of ethics for public officials and establishment of financial disclosure laws. These laws have set forth requirements that must rely more on voluntary compliance and the disciplinary processes of personal administration than on enforcement in the criminal courts. Acceptance of these conditions as part of the terms of public employment has not as far impaired constitutionally protected rights, but financial disclosure laws have raised more serious constitutional issues. [More] | |
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107 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1979
The continuing project, "Synthesis of Information Related to Highway Problems" is intended to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. Reports from this project constitute a National Cooperative Highway Research Program (NCHRP) report series "Synthesis of Highway Practice", which collects and assembles the various forms of information into single concise documents pertaining to specific highway problems or sets of closely related problems. The 56 published syntheses of Highway Practice that have been prepared to date are listed in this digest. Work currently underway on a further 24 topics are also listed. Project procedures concerning the submission and selection of topics are also listed. Project procedures concerning the submission and selection of topics are outlined. This digest also gives brief details of the conduct of the studies. [More] | |
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106 - Use of Waste Materials in Highway Construction and Maintenance
1/1/1979
A study of existing information is reported. Reference is made to a report prepared under the sponsorship of the Organization for Economic Co-operation and Development--"Use of Waste Materials and By-Products in Road Construction"--which reviews the use of materials from mining and quarry wastes and products, metallurgical wastes and by-products, industrial wastes and by products, municiapl wastes, agriculture and forestry wastes and by-products. This study focuses specific attention on economic, environmental, and energy considerations. A summary table is included, which indicates established or potential highway construction uses for each type of waste material. [More] | |
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105 - Selected Acoustical Parameters of Highway Noise Barriers
1/1/1978
A need existed (a) to determine the influence of selected barrier characteristics on barrier performance and (b) to develop procedures to incorporate these effects in the design process. Thus, the objective of this investigation was to examine the manner in which noise propagates over barriers of different cross-sectional shape (e.g., thin walls, sharp wedges, trapezoids, walls on trapezoids, and round-topped berm-like shapes). An additional objective was to investigate and describe the effect of the terrain cover behind a barrier and the effects of partially absorptive barrier coverings on the net effectiveness of noise abatement behind a barrier. The research aimed at accomplishing these objectives was theoretical in nature, being based on adaptations of previously developed theory and carried out with explicit assumptions about conditions of highway alinement, source characteristics, ground surface, and so on. The models thereby reasonably represent realistic highway noise situations. The project has been highly successful in accomplishing its objectives. As yet, however, and pending follow-on work, the results have only limited applicability in practice. As noted, the effects of the barrier parameters were explored in theoretical terms. A second phase of the project, started in 1978, is expected to validate these findings by scale-model testing and measurement. Even so, the current research results will be of interest in their own right to at least two audiences. For readers who are not acousticians, the report has been designed to communicate some feeling for the impacts of the selected barrier parameters on barrier attenuation and insertion loss. For acoustic specialists, the report seeks to provide tools for modifying design manuals. This latter group will find that the report appendices offer comprehensive details for their consideration. /Author/ [More] | |
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104 - NCHRP Research on Bridge Engineering
1/1/1978
The status of all NCHRP bridge related research projects that have been completed, are in progress, or under development, is outlined. The projects listed cover a wide range of problem areas related to design, construction, and maintenance of bridges. Both durability and structural behavior are included, with particular emphasis on methods of prevention and repair of damage caused by fatigue in steel members or corrosion of reinforcement in bridge decks. A listing of all related research reports is also provided, with directions for obtaining copies. [More] | |
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101 - Retrofitting Procedures for Fatigue-Damaged Full-Scale Welded Bridge Beams
1/1/1978
Bridge beams on the east and westbound bridges of span No. 1 at Yellow Mill Pond in Bridgeport, Connecticut, were inspected for fatigue cracking and then retrofitted, using either the peening or the gas tungsten arc remelting procedures. The retrofitted beams were then subjected to fatigue strength tests. The results indicated that both procedures could be used to successfully extend the fatigue life and prevent further crack growth. Only details with initial crack depths greater than 1/8 inch did not achieve the desired life increments. For details with very small or no visible crack, the peening procedure appears to provide a reliable and the most economical means of retrofitting fatigue damage; for details with slightly larger cracks ( up to 3/16 inch deep) the gas tungsten arc remelt process is preferred. [More] | |
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100 - Safe Conduct of Traffic Through Highway Construction and Maintenance Zones
1/1/1978
The principles for safe management of traffic at work zones that were developed are based on operational experience and limited available research results. They include, among others, the following: Traffic safety in the workzone should be an integral and high priority element of every project from the planning stage through the design and operations, careful attention should be given to providing safe areas for storage of equipment and materials and to removing all construction and maintenance debris, the roadway should be kept clear of obstacles as much as possible; worksties should be carefully monitored under varying conditions of traffic volume, light, and weather, to ensure that traffic-control measures are operating effectively. The growing awareness of the importance of traffic controls at construction and maintenance work sites has generated a number of training courses, developed on a national or local level. There have been several studies that deal either directly or indirectly with construction-zone traffic-control devices, design, and operations. Some of the conclusions are as follows: Activities located on a roadway generally reduce the amount of roadway for vehicular travel, motorists often become irritated if construction activities linger on, the volume of traffic on a roadway will affect the selection of types of traffic control to be used in a construction zone. Current research to improve the safety of the travel public and workers in construction and matinenance areas are described as well as future areas for study. It is noted that the legal implications of a highway departments' efforts to conduct traffic safely through construction or maintenance activity zones are extremely important. [More] | |
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98 - Safety at Narrow Bridge Sites
1/1/1977
This study for determining methods (other than widening) for reducing the hazards associated with narrow bridges, included the developing of a bridge safety indes (BSI) for determining priorities in dealing with problems involving bridges having restricted width. The BSI approach is presented in the form of tables and figures readily usable by practicing engineers. An example problem is used to define BSI and permit its direct application to practice. The corrective measures to reduce the probability and severity of accidents at potentially hazardous sites are described briefly: realign roadway where sight distance problems are apparent and traffic control measures appear to fail; replace bridge rail (installation of smooth rail increases probability of redirecting vehicle); change approach grades when grade continuity is a problem; install approach guardrail; place edge lines and transition markers; install narrow bridge and advisory speed signs; install signs and remove centerline strips on one-lane bridges; re- route commercial vehicles; and environmental control of distracting lights and other roadside disturbances. [More] | |
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96 - Continuing Project on Highway Right-of-Way and Legal Problems
1/1/1977
A study project has been established to meet the need of state highway and transportation departments regarding the assembly, analysis and evaluation of operating practices and the legal elements of special problems involving right-of-way acquisition and control and highway law in general. A 1976 publication, which was a product of this project and which fills a void in American legal writing, collects the cases dealing with highways and provides a clearinghouse for analysis and discussion of the rules of law announced therein. This publication will consist of 3 volumes: The first two deal principally with problems in the field of eminent domain; the third volume will deal with highway- related problems in the field of contract law, environmental law, intergovernmental relations, and tort liability of state highway departments and their employees. The selected papers published in the above publication are also published as National Cooperative Highway Research Program (NCHRP) Research Results Digests. [More] | |
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94 - Disaggregate Travel Demand Models
1/1/1977
Disaggregate models are policy-sensitive travel demand forecasting models that are consistent with travel choice theory using data at the level of individual travelers. Such models were found to advance the existing state-of-the-art in explaining present travel behavior. Disaggregate models can also be applied with greater ease than aggregate models to corridor and project planning within urban areas. This study has developed new disaggregate demand models for work-trip mode choice and for shopping choices as follows: Mode, destination, frequency, and time of day. Specific findings related to these models are presented. The report gives hypothetical examples to illustrate how disaggregate models can be used to forecast the effects of travel changes in the price of gasoline, of a reduction in off-peak transit fare, of an increase in driving time to the downtown, and of change to the transportation models available to individuals. [More] | |
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93 - Impact Assessment Guidelines for Evaluating the No-Build Alternative in Transportation
1/1/1977
The general objective of no-build research has been to strengthen the techniques and procedures available to transportation planners and engineers in three areas: The definition of no-build alternatives; the prediction and measurement of the consequences of no-build alternatives; and, the use of no-build alternatives in plan evaluation. This objective has been partially met with the development of a set of interim quidelines and a Phase I research report. The quidelines are organized as follows: introduction and summary; the role of the no- build alternative; definition of alternatives; impact assessment; plan evaluation. Four technical appendices include: techniques dictionary: glossary; notes on the impact assessment process; and, references. These guidelines will be of use to all professionals concerned with the analysis of transportation alternatives, and all will benefit from gaining an understanding of the role of the no-build alternative and how it may be structured. [More] | |
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92 - Freight Data Requirements for Statewide Transportation Systems Planning
1/1/1977
Since freight planning on a statewide basis is in the early stages of development, a basic core of knowledge about goods transport must be developed and existing freight data source material must be identified. This project determined the data requirements for statewide freight transportation planning and prepared a manual on how the states may obtain primary and secondary data. The result was an extensive catalog of freight data sources for use by state and regional planners. Procedures and techniques for obtaining primary and secondary data are described. Five types of planning activities and analysis techniques were examined to determine specific data requirements: demand forecasting, mode choice analyses, network analysis, economic evaluation, and impact estimation. States are not advised to conduct their own primary surveys except in cases where limited, specialized information is required that is not available from any other source. States should generally rely on existing secondary data for freight transportation system planning purposes. The specific methods presented in the user manual were taken from previous planning studies and can be successfully applied by other agencies. [More] | |
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91 - Motorist Response to Guide Signing
1/1/1977
This study of the relationships among the many measures of response to signs encompassed by Sections 2E and 2F of the "Manual on Uniform Traffic Control Devices", was oriented toward methods that can be implemented readily by the staffs of traffic engineering organizations. Phase I of the project, the identification of potential MOE's (measures of guide sign effectiveness) and other sources of variance, involved review of 300 documents in 3 categories: vehicle action; driver information processing; and driver predisposition. Phase II addressed the key issues of field evaluation of potential measures and assessment of the suitability of various methods to obtain those measures. The sign-relatedness of each candidate measure is summarized. All studies established 4 target behaviors (detection, interpretation, preference, information processing) as guide sign MOE' s. Group differences linking driver sign responses with each behavior is also summarized. The driver factors and vehicle performance selected for evaluation in the field studies are discussed. The field study findings including target behaviors and microflow vehicle performances are presented, as well as a number of methods for the collection of derived MOE's. [More] | |
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90 - Continuing Project to Synthesize Information on Highway Problems (Superseded)
1/1/1976
A project is reported which is designed to search out and synthesize useful knowledge from all possible sources and to prepare documented reports on current practices in the subject areas of concern. A product of these effort is the report series, "Synthesis of Highway Practic" which assembles information into concise documents pertaining to specific problems. For each topic, the project objectives are to: locate and assemble documented information; learn what engineering practice has been held for solving the problems; identify ongoing research; learn what problems remain unsolved; evaluate and document the information; and evaluate the effectiveness of the synthesis. The sources of information include, among others, the state transportation and highway departments. The 39 published synthesis prepared to date and listed as well as the 22 topics currently being investigated. [More] | |
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89 - Guidelines for Skid-Resistant Highway Pavement Surfaces
1/1/1976
The work is outlined and the findings are summarized of a project to identify and evaluate procedures suitable for implementation that will improve resistance of pavements to polishing and wear caused by conventional and studded tire traffic. The project was also designed to identify innovative procedures for improved wear-resistant and skid- resistant pavements, and evaluate (by experimentation) selected procedures. The ten systems selected as most suitable are: portland cement concrete with sharp, polish-resistant fine aggregate and coarse texture (tined) surface; dense-graded asphaltic concrete with polish- resistant coarse aggregate; open-graded asphaltic concrete with polish- resistant coarse aggregate; gap-graded asphaltic concrete with polish- resistant coarse aggregate; asphaltic concrete with rolled-in, precoated, polish-resistant chips; epoxy-modified asphaltic concrete with polish resistant coarse aggregate; asphalt seal coat with polish- resistant chips; rubberized asphalt seal coat with polish-resistant chips; and sawed longitudinal grooves in existing portland cement concrete. Five descriptive groupings are suggested for the purpose of identifying potentially promising aggregates for the desired level of service. The final report covers the applicable type and condition of pavement, traffic conditions, performance, laboratory and field work, and specifications for materials and construction. [More] | |
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88 - Summary of Project 3-18(3) Traffic Signal System Surveys
1/1/1976
A questionnaire survey was conducted which was designed to identify and define the range of traffic surveillance and control system alternatives to which a cost effectiveness methodology (for evaluation of signalized street network surveillance and control systems) is to be applied. Tables and commentaries are presented related to responses from researchers, designers and manufacturers who were asked for both qualitative and quantitative answers to questions about preliminary studies (plans, specifications, estimates), construction, management, and system effectiveness. Information on selection criteria concerning the range of alternative systems use, evaluation, design and implementation of systems, operational and maintenance aspects were collected from systems users. The survey showed that evaluation methodologies must be sensitive to local policies and traffic control philosophies, and expected system levels of performance. Respondents using digital computer systems reported a greater need for engineering personnel, rated components as having lower reliability than agencies with non-digital systems, needed and used more timing plans and felt system flexibility was more important. Findings related to backup capabilities, display map, and the establishment of performance criteria are also reported. [More] | |
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87 - Current Practices in Use of Retroreflective Signing Materials
1/1/1976
The major findings are presented of a questionnaire survey (of what material combinations are being used and the basis for their selection) which was part of a research effort to define the optimum relationship between sign background and legend luminance as a function of several pertinent variables. The questionnaire elicited information on the types of signing material; paractices relating to illumination; inspection and maintenance practices; criteria and methods for refurbishing existing signs, and determining the time of replacement; and the useful life of various sign face materials. Material combinations must frequently used are summarized in a table. The combinations must frequently mentioned were button copy on paint or porcelain enamel and button copy on engineer-grade sheeting. With reference to sign employing direct-applied letters, symbols, or legends, material use was evenly divided between engineer grade and high-intensity sheeting. Findings related to illumination of road signs, photometric specifications, quality control, maintenance and replacement are also discussed. [More] | |
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85 - Bridge Deck Repairs
1/1/1976
The findings are presented of the preliminary field survey stage of a study designed to determine the relative effectiveness of the various repair methods in arresting corrosion of the reinforcing steel, and whether some of these methods could actually aggrevate the corrosion problem. This effort reviews the causes of deck deterioration, and analyzes the preventive and remedial solutions that have been applied to the problem. Primary attention was directed to the problem of delamination and spalling of concrete bridge decks due to salt- accelerated corrosion of the reinforcing steel. The survey indicates a great diversity in bridge deck repair practices. Methods for evaluating the condition of concrete bridge decks include electrical potential measurements, delamination detection, chloride analysis, nondestructive measurements of concrete and construction, and visual assessments. The bridge deck repair and rehabilitation rationale ( responsibility for monitoring, decision-making related to optimum repair, etc.) are detailed. An FHWA classification which includes 3 categories that reflect deck condition is outlined, and temporary, permanent and replacement methods are briefly discussed. Repairs involving placement of cold-mix AC in spall-holes is the most commonly used. More permanent repairs involve a number of factors including removal of deteriorated concrete, removal of corrosion product, application of bonding agent, and placement of repair material plus overlay or membrane. Comments are made regarding overlay materials and the depth and extent of removal of unsound or chloride contaminated concrete. [More] | |
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83 - Liability of State and Local Governments for Snow and Ice Control
1/1/1901
Generalizations on the probability of jury verdicts for plaintiffs, and the relative size of jury awards where a governmental body is the defendent are noted, the erosion of sovereign immunity is discussed, the current state of liability of Federal, State and local governments is reviewed, and comments are made on the duty to remove snow and ice. Limitations of duty, care concerning use of abrasives, governmental- proprietary test of immunity, and discretionary-ministerial duty test of immunity are also discussed. Public authorities at the city, county and state level are now liable in tort for negligence in the failure to remedy snow and ice hazards on the highways. Cases hold public authorities liable in many instances where they fail to salt or sand an icy road hazard or rail to provide adequate warning of danger. In those jurisdictions having "highway defect" statutes the courts hold that specific snow and ice hazards that are untreated or have inadequate warning may constitute a highway defect. Defenses of public agencies for negligent snow and ice removal do not appear to include immunity for governmental action, several courts holding that snow and ice removal and the use of abrasives constitute maintenance or proprietary activity. The defense that snow and ice control is a "discretionary activity" and, therefore, innune from liability also appears to be inapplicable, whether an action is brought in a common law jurisdiction or in one having a tort claims act. A snow and ice removal program, however, adopted by a public body having discretionary authority that contained an inadequate or defective feature may be immunized because of the courts' reluctance to second-guess the judgements of public authorities with legislative or quasi-legislative attributes. However, this initial immunity may be lost or fail to attach under certain circumstances. It is pointed out that there may be a duty to review any snow and ice control program in order to discover and correct any features that are hazardous in actual operation. [More] | |
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82 - Design of Continuously Reinforced Concrete Pavements for Highways
1/1/1976
This report summarizes the essential findings of a research study undertaken to develop an improved structural design procedure for continuously reinforced concrete pavement. A three-directional approach consisting of a theoretical study, field surveys, and a laboratory investigation was used in the research effort. The theoretical study produced a design behavioral model that solves for the state of stress and strain in CRCP systems resulting from drying shrinkage and temperature drop. A computer program, CRCP-1, was developed for application of the model in pavement design. Information obtained in field performance surveys at 133 pavement locations in 14 states was used in the development of a series of regression models for use in design as an alternate to, or in conjunction with, CRCP-1. The laboratory work involved repetitive load studies made on ten continuously reinforced slabs 3 ft x 6 ft x 4 in. cracked at mid-panel. Data from the laboratory study were used to develop regression equations to predict surface spall and deflection at cracks due to traffic loading. Water penetration was also investigated. The full study led to the proposal of a step-by-step design process that can be given practical application once several limiting criteria that are now missing are established. The field study also produced several observations of performance that may be of assistance to future CRCP users. [More] | |
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81 - Crash Testing and Evaluation of Attenuating Bridge Railing System
1/1/1976
The results of the analysis (using computer program BARRIER IV) of an idealized vehicle barrier system indicate that the barrier which was designed to prevent penetration by a standard-size automobile weighting 4,000 to 5,000 lb and impacting at 25 deg. and 65 mph, would meet the desired criteria. A key feature of this steel bridge rail design is the function of the attenuator that supports the two rails of gectangular structural tubing. It is designed to absorb energy as it deforms on impact; the resisting force builds up, yeilds plastically and remains at a relatively constant level around 13 kips through about 36 in. of deformation. Three full-scale vehicle crash tests were conducted and the results are summarized in a table. Two attenuators were subjected to static force-deformation tests to document their energy absorbing characteristics, and to dynamic pendulum tests for the same purpose. Although attenuator design does not meet current AASHTO specifications, the railings may be exempted from conforming because they have been successfully tested by full-scale impact tests. The attenuating bridge railing concept is concluded to be a very attractive simple system providing excellent driver visibility, and is recommended for immediate application. [More] | |
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80 - Liability of State Highway Departments for Design, Construction, and Maintenance Defects
1/1/1901
Four principles involved in a tort action for negligent design, construction, and maintenance are discussed: (1) a primary defense is the state's immunity from suit and liability; (2) in those states where the action is based on a general waiver statute the case is decided in the same manner as any negligence or personal injury action, with certain exceptions; (3) in many jurisdictions the action is purely statutory with a distinctive body of case law and procedures; (4) the question presented where tort claims are in force usually is whether negligence in the plan or design, construction, or maintenance of the highway is "discretionary" and therefore immune. The various approaches and principles pertinent to the defense of sovereign immunity, the statutes waiving tort immunity of the department, the governmental- proprietary test of immunity, and immunity based on discretionary function or activity are detailed, and relevant cases are quoted. Tort liability has received varying treatment by the courts. In a few jurisdictions, the state cannot be sued without its consent; in others suit may be instituted only in a prescribed manner; and in still others, suit may be authorized only where it falls within the ambit of some special highway statute creating liability for breach of duty. Although the laws sometimes permit tort suites of this nature based on negligence principles as if the state were a private person or corporation, the prevailing trend is to authorize suit only as set forth by the legislature in a tort claims act. The cases are fairly uniform in holding that the design of a highway is discretionary because it involves high-level planning activity with the evaluation of policies and factors. Exceptions to design immunity which have been noted by the courts are listed. Negligent construction is not likely to be immunized by reason of the discretionary function exemption. However, it might be immunized where the plan or design specifies in elaborate detail how a feature is to be completed. Negligent maintenance is least likely to be immune from liability. [More] | |
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79 - Personal Liability of State Highway Department Officers and Employees
1/1/1901
The legal questions sorrounding liability for negligence by highway department personnel and the legal authority relative thereto are reviewed. Influenced by various reasons for treating public officials differently from private persons with regard to liability for torts and other policy considerations, the law developed along the lines of conditional immunity. Cases adopting the theory of absolute immunity are reviewed in which the rationale developed is that because a county cannot be held liable for view has been taken that a suit against public officals is no different from that against private persons. Of the various tests evolved to determine whether liability should be imposed, the most important is the test of whether the activity is discretionary or ministerial. The special privileges afforded to judges are discussed and the terms involved in the concept are defined. The planning operational dichotomy adopted by the Federal Courts in interpreting the discretionary exemption of the Federal Tort Claims Act serves to explain the results of cases. Specific aspects of highway design that have been held to be discretionary are listed. Maintenance activities at the planning stage, as opposed to maintenance activities at the operational stage, which are held to be within discretionary exemption are reviewed. Although the operation of a motor vehicle by a highway department employee is considered a ministerial duty, 2 cases are quoted which hold that the operation of a snowplow cannot be so classified. It is pointed out that discretionary exemption does not extend to situations in which an official has exceeded his jurisdiction. Cases are described that enunciate a distinction between public duties and private duties. Cases involving misfeasance- nonfeasance are also reviewed. Three cases are described in which the defense of acting under orders was successfully interposed. It has been firmly established that the doctrine of respondent superiority has no application to public officials, and that the state is entitled to indemnification against the employee where the state has responded in damages for the negligence of that employee. [More] | |
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78 - Traffic Signal Warrants -- A Bibliography
1/1/1975
This annotated bibliography of relevant literature was compiled in an effort to evaluate the adequacy of existing warrants in meeting current needs for determining whether a traffic signal should be installed, and to determine the need for revised or additional warrants. The literature reviewed in the preparation of the bibliography was restricted to material published since 1967 and the references are restricted to those pertaining to traffic signal warrants for isolated intersections. The bibliography consists of 2 parts: the first covers the general subject area and contains 152 entries; The second, containing 29 entries, includes supplementary material on accident occurrence and costs. [More] | |
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77 - Earth-Berm Vehicle Deflector
1/1/1975
In an attempt (limited) to provide factual information that could be of assistance toward rationalizing the selection of earth-berm configurations as safety elements in the highway system, a modified version of the Highway Vehicle Object Simulation Model (HVOSM) was used to investigate vehicle behavior on earth-berm slopes. Rigid-body mechanical equations were also used to predict vehicle paths. Details are noted of the initially assumed operating conditions for the computer simulations as well as of additional simulations. The results of computer simulation analysis led to the selection of a berm with a slope of 1.2:1, a height of 12.5 ft, and a length of 250 ft for construction and full-scale testing. Two criteria were used to judge the capability of the earth-berm slopes to safely restrain or redirect traversing vehicles: vehicle rollover and vehicle accelerations tolerable to humans. Five full-scale lists were conducted using a 1963 Ford Galaxie similar to the vehicle used in the computer program. The results showed that the peak and average accelerations (g's) that occurred when full-scale vehicle impacted 1.2:1 earth-berm slope and the length of berm traversal were in good agreement with those predicted by the HVOSM computer simulation. The vertical height of vehicle climb was about twice that which was predicted by computer; two unpredicted rollovers also occurred. Relatively simple rigid-body equations that neglected friction between the vehicle and the slope surface and assumed the vehicle mass to be concentrated at a point showed promise as a means for estimating the height of the vehicle climb and the length of the slope traversal. It was concluded that although very steep slopes (1.2:1 and steeper) are not appropriate for earth berms it is recommended that this research approach be applied to further studies in the field. [More] | |
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76 - Field Evaluation of Vehicle Barrier Systems
1/1/1975
Two studies are reported. The study initiated by Calspan Corporation which concentrated on accident statistics, was planned to determine the degree to which accident data currently being accumulated by various agencies can be used to evaluate the field performance of barrier systems and, if warranted, to recommend new approaches that may better be used to make such an evaluation. The second study (by A.L. Elliot) set out to determine the feasibility of evaluating barrier systems through personal interviews with maintenance, safety, and traffic operations personnel in highway agencies; five representative states were visited for this purpose. In the Calspan study, specific data items of interest were identified through analysis of available data, a survey of highway departments, and discussions with the project advisory panel and with individuals in government and private agencies. This data was combined with that from the experience of Calspan personnel in highway accident investigation, crash test programs, barrier design and testing and statistical analyses to determine the data items appropriate to evaluations of barrier performance. The study identified the spot improvement programs conducted in most states as the best potential source of data at present. The study concluded that because of the variations among states with respect to barrier systems, comparative evaluations require some central national system of data collection. The inclusion of a limited amount of barrier information in a broader program by the Federal government appears the most feasible. This will permit statistical evaluation and the detection of problem areas for special study. Mr. Elliot's study concluded that his informal approach to barrier evaluation has real merit and that useful data may be obtained by visiting with selected individuals in a small number of representative states. [More] | |
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75 - Development of Prototype Soil Moisture Sensors
1/1/1975
In an effort to develop innovative sensors for the in situ measurement of moisture in aggregate base and soil subgrade layers of pavements, two prototypes have been developed and laboratory evaluated: a sensor based on nuclear magnetic resonance (NMR) technology and a sensor using dielectric constant technology. Both sensor types are potentially applicable to highway soil moisture measurement problems. Each sensor measures the amount of water in the effective volume of a soil sample and is somewhat influenced by soil type. For a particular soil of known dry density, the percentage water on a dry weight basis can be determined by empirical calibration. Under an extension of this study, the sensors are undergoing (1) refinement and development of ancillary readout equipment; (2) simulated field evaluation over a range of soil, compaction, moisture, and contamination conditions; and (3) field installation and practical evaluation in two different climatic regions. The NMR sensor based on the spin echo approach was tested with bentonite clay, silica flour, and an organic silty clay. The influences of soil density, organic matter and dissolved salts were investigated. In the prototype dielectric model, the sensor electrodes are incorporated as part of a resonance circuit whose frequency of oscillation circuit is contained within the buried sensor; a coaxial cable connects the sensor to the external power supply and readout instrument. It is hoped that in addition to the original objectives, the technology developed in the study may be applied to the development of laboratory instruments for instantaneous measurement of moisture in soil samples without the need for drying. [More] | |
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74 - Electroslag Weldments in Bridges
1/1/1975
In an effort to develop and verify acceptance criteria for the use of electroslag welds in bridges, a 2-phase research project has been initiated. Phase I which is designed to define the necessary acceptance specifications, will include a review of literature; a state- of-the-art report on electroslag welding; testing of laboratory specimens from full-scale welds; development of tentative acceptance tests and criteria for electroslag butt-welds based on the results of previous tasks; a summary of the Phase I findings and a work plan for phase II. Electroslag welding is defined as a process wherein coalescence is produced by molten slag which melts the filler metal and surfaces of the work to be welded. The weld pool is shielded by the slag, which moves along the full cross section of the joint as welding progresses. The conductive slag is maintained molten by its resistance to electric current passing between the electrode and the work. Welding is done in the vertical or near-vertical position, and joints are generally accomplished in a single pass regardless of the thickness to joined. The advantages and disadvantages of the process are listed, and the principles of operation are outlined with special reference to the conventional wire process and the consumable-guide process. Equipment for both processes, and the different power supplies are discussed. The base materials and electrodes used for welding as well as the fluxes and consumable guide tubes are reviewed. The process variables discussed here include joint geometry, thermal cycle, solidification pattern, form factor, imperfections, and distortion and residual stress. Current opinion regarding the mechanical properties of as-deposited electroslag weldments in structural steels is summarized with special reference to tensile properties, notch toughness fatigue and other properties. The results obtained in various testing methods are discussed. [More] | |
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72 - Recommended Modification of Superelevation Practice for Long-Radius Curves
1/1/1975
In an effort to develop guidelines for highway geometrics and pavement surface characteristics which will ensure adequate vehicle control during anticipated maneuvers on highway sections containing a combination of horizontal curvature and vertical grade, an extensive analysis was performed of accident data, computer simulation studies were made, and an in-depth investigation was made of two high-accident sites. The results of the study indicate that drivers are not likely to loose control of their vehicles on curve-grade sites unless they are attempting to perform severe maneuvers on slippery road surfaces with fair to poor tires. It is noted that the AASHTO design procedures as described in "A Policy of Geometric Design of Rual Highways, 1965" and a "Policy on Design of Urban Highways and Arterial Streets, 1973", provide sufficient guidance for geometric design of sites with combined horizontal curvature and vertical grade, provided (1) the selected values of superelevation are large enough to result in adequate pavement surface drainage, and (2) the pavement skid resistance is sufficient for anticipated vehicle maneuvering. Due to the safety implications of the findings and the fact that they are based on both computer simulation studies and accident analysis, certain actions are suggested. AASHTO procedures are briefly reviewed and comments are made on highway agency superelevation practices, reducing driver demand, and existing high-accident sites. [More] | |
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66 - Nondestructive Methods of Fatigue Crack Detection in Steel Bridge Members
1/1/1975
This summary of the state-of-the-art in nondestructive inspection methods, evaluates their reliability and adaptability for the detection of fatigue cracks in welded highway bridges. Emphasis is placed on in- situ testing and on the capability of techniques to define cracks accurately in terms of length and depth. The underlying concept of fatigue failure prevention in explained, and five testing techniques are described. Details of X-ray examination are briefly outlined. The X-ray image on film provides a permanent record of the size and shape of the defect in two dimensions; it does not show its position in depth in the part. In ultrasonic examination, instrumentation includes a sound wave generator and pick-up device and a display screen on which the initial and reflected pulse is displayed. The display instrumentation permits estimation of the position, nautre and size of the defect. The details (modifications, advantages and disadvantages) of the dye penetrant examination, the magnetic particle examination and the eddy current examination are discussed. The general features of these five methods are summarized in a chart. The study indicates that the best methods for surface crack detection are magnetic particle and dye penetrant examination. The opinion is also expressed that the ultrasonic examination would be the most effective for fatigue crack detection if only one nondestructive examination system could be used. The current capabilities of nondestructive examination methods are reviewed, and practical field crack detection is discussed. [More] | |
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65 - Design of Bent Caps for Concrete Box Girder Bridges
1/1/1974
Research is reported that was planned to develop design procedures for bent caps which would include consideration for the location and distribution of critical AASHTO loading for a bent cap, the effect of flaring a column, the effective width of a bent cap, the effect of spreading bent cap reinforcement into an adjacent box girder slab, and the location of critical cross sections. The research which was conducted in two phases (analytical and experimental) consisted of studies of load distribution in bridge entireties and stress distribution in bent caps on two phototype bridges, and the construction and testing of seven scale models. Two of the models, built to one-fifth scale of the prototype bridges, were representative of popular reinforced concrete box girder designs. Model tests provided information on the distribution of loads in the vicinity of integrated bent caps. Another five models represented transverse strips of bridge superstructures parallel to, and including, the bent caps and columns. Column flare and the amount and distribution of bent cap reinforcement varied in these models. These tests provided information about critical sections and the effective width of bent caps. The recommendation is made (based on the results of the investigation) for the use of present AASHTO design methods. It is also recommended that for an integral support to be considered effective, the angle of greatest slope of the surface of the support shall not exceed 45 degrees from the vertical. Conditions governing the effective width of an overhanging compression flange on either side of the web of an integral bent cap are listed as well those conditions governing the effective width of an overhanging tension flange on either side of an integral bent cap. Regarding the design section for negative moment, it is recommended that moments at the face of support may be used for design of the bent cap. The face of support is defined as the limit of the effective support along the center line of the bent cap. The recommendation related to the effect of spreading reinforcement urges the use of provisions specified for the effective flange width tension. Observations are also reported which relate to one of the primary aims of this study, namely, to determine if current design methods resulted in more reinforcement than needed in the bent cap. [More] | |
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64 - Roadway Design in Seasonal Frost Areas
1/1/1974
An NCHRP Synthesis of Highway Practice reviews and synthesizes current pavement design procedures in seasonal frost areas, as well as construction and maintenance practices, and identifies those that might be of greatest value to other road agencies. The study consisted of a literature review, a questionnaire survey of North American road design agencies, and visits to ten agencies for discussion of their practices. The findings of the study are divided into the major categories of (1) factors fundamental to frost action, (2) the process of design, (3) construction and maintenance, and (4) research needs. This Digest concentrates on the portions of the report dealing with design, construction, and maintenance activities for minimizing the detrimental effects of frost action on pavements. [More] | |
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63 - Evaluating Procedures for Determining Concrete Pavement Thickness and Reinforcement Position
1/1/1974
This report summarizes the results of a study that evaluated currently available nondestructive testing systems that appeared to have potential for supplementing or replacing coring in determining concrete pavement thickness and reinforcement location. The evaluation was done primarily in the field. The principal work consisted of the systems under on-the-job conditions on eight paving projects in six states. The measurement techniques were employed in conjunction with statistical acceptance criteria evolved in the course of the study. An ultrasonic gauge developed by the Ohio State University was found to perform thickness measurements on hardened concrete for both plain and reinforced pavement with acceptable accuracy. Before it can be applied routinely, further improvement of its resistance of the rigors of job- site conditions is needed. An eddy current proximity gauge proved satisfactory for measuring the thickness of hardened plain concrete pavement, but not of reinforced pavement. A device called a " pachometer" was found to be satisfactory for determining the depth and position of steel reinforcement in both plastic and hardened concrete. [More] | |
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62 - Systems Approach to Flexible Pavement Design and Management
1/1/1974
A project is reported which resulted in the improvement of the computer program, SAMP5, to an operational program, SAMP6, which provides a basis for selecting flexible pavement design and management strategies with the lowest predicted total cost over a prescribed analysis period when considering such cost elements as initial construction, routine maintenance, periodic rehabilitation, interest on investment, salvage value, and roadway user costs. The SAMP6 program uses the AASHTO Interim Guides as its structural subsystem and the predicted decreases in serviceability with time and traffic as developed at the AASHO Road Test. The SAMP6 is capable of considering all aspects of the systems approach to pavement design and management except those of the cost of seal coats and the cost of skidding accidents. The program requires 12 classes of input variables: program control and miscellaneous variables, environmental serviceability, traffic and reliability; constraint; traffic delay; maintenance; cross-section, cost-model, shoulder; track coat, prime coat, bituminous materials; wearing surface; overlay; pavement material; and shoulder material variables. The output of the SAMP6 program is provided in three parts: Summary of the input data; summary of the best design strategy for each material and layer combination; and a summary of the 80 best design strategies in order of increasing total cost per square yard of traffic lane. The results are given of a limited sensitivity analysis conducted to provide an indication of the influence of the individual variables on the output. As an illustration of the application of SAMP6, a comparison is described of the economics of staged construction and planned rehabilitation versus the "no-overlay", or a strong initial construction approach. Another illustration involved the effect of fluctuating material costs on optimum design. [More] | |
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61 - Wear-Resistant and Skid-Resistant Highway Pavement Surfaces
1/1/1974
Procedures for improving the resistance to wear and polishing of new pavements, and for correcting worn or needs and the associated problems, and how to implement literature was extensively reviewed and method is described for classifying pavement systems with regard to wear and skid resistance, tentative performance criteria. Recommendations are made for use of the systems judged to be most suitable for practical application. An annotated bibliography of more that 500 items on the subject is presented and recommendations are made for more innovative pavement systems. The findings of the investigation are outlined and a brief description is given of ten systems selected as suitable for immediate practical application. Aggregates (selection of which is of prime importance in the design of a wear-and-skid-resistance surface) are divided process, with the assumption that the proposed limits are classification may be employed as a guideline for the selection of fine aggregate to produce polish- resistant portland cement concrete where the surface motar is a more entitled "a motorist radio service" is supported by the resistance than is coarse aggregate. For asphaltic concrete, asphalt surface treatments, and similar systems, it is the coarse aggregate that is more important. The selection of an optimum system for a specific location is discussed. [More] | |
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60 - Fatigue of Welded Steel Bridge Members Under Variable-Amplitude Loadings
1/1/1974
A project is reported the objective of which is to acquire fatigue data on welded bridge members under variable-amplitude random-sequence stress spectrums, such as occur in actual bridges, and to develop an analytical method of predicting variable-amplitude fatigue behavior from constant-amplitude fatigue data. Pertinent past work was studied with particular emphasis on field mearurements of stresses in bridges under traffic. A theoretical study was made to predict, from various hypothese, the fatigue behavior of the small specimens and beams being tested during the program. A program of variable-and constant- amplitude fatigue tests of small specimens was performed to obtain crack growth data and to determine the effects of various stress- spectrum parameters on fatigue life. A program of variable- and constant-amplitude fatigue tests of relatively large beams of various steels was also performed. The results were evaluated, and methods of utilizing the results for design and specification purposes were developed. Field stress measurements of bridges under traffic were collected and evaluated. Distributions were then selected for the variable amplitude stress spectra to be used in the experimentation. An experimental program was also planned on small plate specimens and large beam specimens. Details of the experimental program are outlined. The project findings are discussed and the test results are reviewed. The results of the study provide a link between the type of variable-amplitude random-sequence fatigue loadings that actually occur on bridges and the constant-amplitude fatigue data and allowable stress values that are commonly used in designing such bridges. Applications of the findings are reviewed. [More] | |
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55 - Side-Friction Factors in the Design of Highway Curves
1/1/1974
In order to provide an evaluation of the current AASHTO curve design Standards and to provide the information necessary to substantiate any proposed changes in these standards, a study was made of (part of the complex system of interaction between driver, vehicle, and pavement) those physical characteristics of the vehicle and the pavement that influence the critical cornering maneuver. The study consisted of: the use of mathematical simulations of motor vehicles traversing highway curves; the evaluation of mathematical simulations by means of full- scale vehicle tests; and use of the mathematical simulations in parametric studies to evaluate current AASHTO curve design standards. A modified version of an advanced simulation model was used. Full- scale tests with two vechiles, a 1964 Ford and a 1971 Pontiac, were used to validate the simulation. Details of the vehicle/time combinations are outlined. A modified point-mass equation, similar to the classic equation upon which current AASHTO desing standards are based, was used in the analysis. Results of the study indicate that the current AASHTO geometric design policy will in most cases provide safe, conservative designs for highway curves. The specific findings of this study which are classified as 'direct' and 'indirect' are listed. A major finding of this study is that the skid number (SN) as measured with an ASTM locked-wheel skid trailer equipped with highway- type tires, is a reasonable indicator of the average lateral pavement skid resistance available to cornering vehicles using the same tires when traversing long-radius highway curves (oner 800-ft. radius). [More] | |
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51 - Traffic Control in Oversaturated Street Networks
1/1/1973
The scope and magnitude of the oversaturation problem was defined and the way it may best be combatted with existing methods was determined. The paper reports the beginning of a research process leading to improved operation and controls for oversaturated networks. Six specific objectives of the research are listed. The project was planned in three phases. Phase I was concerned with the definition of the problem and determination of its scope and magnitude. Phase II covered the examination and evaluation of existing traffic control techniques. The third phase dealt with the description of advanced methods of traffic control and with the formulation of a detailed plan and program for test and application of the recommended procedures. The first phase was accomplished by a questionnaire surveys of cities, counties and states in the U.S. and Canada. A figure is presented which illustrates the variation of saturation reported by city size for CBD signalized intersections and for all intersections on the arterial system. The que length characteristics at congested intersections is illustrated by a figure which gives an indication of the range of oversaturated intersection experiences by city size. Information on the means used for timing signals is tabulated. Measures of effectiveness to characterize particular aspects of traffic performance are categorized, and a set of que-related measures was selected as being the most promising for study. In the second phase of the study, a literature review and survey response, identified four causes of congestion. The most effective measures for alleviating the problem are listed. It was found that operational measures leading to increased link storage were more effective in delaying or eliminating oversaturation than were measures aimed at increasing intersection capacity. Some particular findings with respect to signal techniques are presented. In the third phase, 4 relevant advanced control concepts were selected from a review of the literature and each was subjected to an extensive simulation evaluation using three different test networks. The research conducted as part of this study has demonstrated that many existing operations and control techniques can be applied to the reduction or elimination of oversaturation. [More] | |
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50 - Determining Pavement Skid Resistance Requirements at Intersections and Braking Sites
1/1/1973
THE DETERMINATION OF SKID RESISTANCE REQUIREMENTS FOR ANY GIVEN SET OF ROADWAY AND TRAFFIC CONDITIONS IS REPORTED. THE STUDY FOCUSES ON WET PAVEMENT SKIDDING ACCIDENTS AT INTERSECTIONS AND CURVES. THE FEASIBILITY OF IMPLEMENTING THESE PROCEDURES WAS DEMONSTRATED IN THE FIELD. A SIMPLIFIED VERSION OF THE PROCEDURES WAS ALSO DEVELOPED. THE THREE STEPS INVOLVED IN THE PROCEDURE FOR DETERMINATION OF SKID RESISTANCE REQUIREMENTS ARE OUTLINED. THE SYSTEM DEVELOPED FOR MEASUREMENT OF LONGITUDINAL ACCELERATION AT INTERSECTIONS IS BASED ON THE USE OF A SERIES OF EVENT DETECTORS TO DETERMINE THE TIME-POSITION SIGNATURE OF A VEHICLE OVER SOME KNOWN DISTANCE, FROM WHICH ACCELERATION VALUES CAN BE COMPUTED. DATA WAS COLLECTED FOR AN AVERAGE OF 350 VEHICLES AT EACH OF 12 INTERSECTIONS. CONTROLLED SKID STUDIES WERE CONDUCTED TO DETERMINE THE RELATIONSHIP BETWEEN LONGITUDINAL ACCELERATION AND SKID RESISTANCE REQUIREMENTS. A SIMPLIFIED INTERSECTION DEMAND MODEL (IDM) FOR ESTIMATING SKID RESISTANCE IS DESIRED. THIS IS BASED ON THE APPARENT NORMALITY OF DISTRIBUTION OF OBSERVED DECELERATION VALUES AT THE VARIOUS DISTANCE INTERVALS FROM THE STOP LINE OF THE 12 SITES STUDIED. THE FINDINGS INDICATE A STRONG RELATIONSHIP BETWEEN PAVEMENT SKID RESISTANCE AND LOCKED WHEEL BRAKING DECELARATION. ACCELERATIONS AND SPEEDS OF VEHICLES BRAKING AT INTERSECTION ARE NORMALLY DISTRIBUTED AND EXHIBIT STABLE STANDARD DEVIATIONS. A RELATIONSHIP EXISTS BETWEEN AVERAGE APPROACH SPEED AND SKID RESISTANCE REQUIREMENTS. CONSIDERABLY MORE EXTENSIVE FIELD EVALUATIONS ARE NECESSARY TO VERIFY THE APPLICABILITY OF THE PROCEDURES. [More] | |
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47 - Trial Strategy and Techniques Using the Comparable Sales Approach to Valuation
1/1/1901
This paper describes the various strategies and techniques that have been used successfully by the author with respect to the comparable sales approach to valuation. The psychology of a trial, the selection of the jury, the valuation witness and trial preparation are discussed as they relate to the trial outcome. Fair market value, comparable sales approach to value, admissibility of evidence of sales made to a condemming agency, elements of comparability, trial tactics, the use of evidence, selection of witnesses, and the role of the judge are also discussed. [More] | |
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46 - Control Logic for Traffic Signal Networks
1/1/1973
In an effort to develop and spread the know-how for effective innovative methods of computer traffic control, work is reported of the formulation, development and evaluation of an operational software system that represents a significant step in the direction of attaining self- adjusting real-time control applicable in both light traffic and heavily congested conditions. The ASCOT (Adaptive Signal Control Optimization Techniques) software system described here is being tested and evaluated on an installed control system with actual traffic. The system is designed to achieve very flexible modes of traffic control such as: on-line signal plan computation; cycle-to- cycle split variations; cycle-length adjustment, coupled with offset changes at congested intersections; and phase- skip on designated signal phases in the absence of demand. The logic can adapt to conditions affecting an entire network, such as adverse weather, as well as to localized conditions that may affect only a single intersection. The three levels of control of the logic are summarized in a table. The ASCOT software implementation in San Jose, California is outlined. Details are briefly described of the evaluation of the control logic which is based on comparison of total travel times for all vehicles operating in a controlled network. Travel time data are collected by floating-car technique, and expressed in vehicles per hour as a function of service rate in vehicle-miles per hour. An event recorder is described which is used for the field evaluation studies. It is expected that in the final report, ASCTO's functional specification will be sufficiently detailed to enable the widest possible applications on a variety of digital computers and a variety of city networks. [More] | |
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45 - Exclusion of Increase or Decrease in Value Caused by Public Improvement for Which Lands Are Condemned
1/1/1901
Apposite cases of both condemnor and condemnee are collated, discussed and analyzed in the light of federal legislation. Emphasis is placed on the identification of the underlying rationale in recent cases. The paper addresses the problem of whether to include or exclude, in the valuation of lands condemned for a public improvement, enhancement or dimunition value attribute to the improvement. The uniform Relocation Assistance and Real Property Acquisition Act of 1970 is outlined, and case law is reviewed with a view to determining what problems will be presented to the states in making full compliance with the provisions of the law. The basic arguments for and against the allowance of enhancement in value due to a public improvement are summarized. The probability of the inclusion tests, and the condemnation of an unenlarged and an enlarged project are discussed. In a few decisions, enhancement in value has been denied without reference to or reliance on the probability of inclusion test. Cases are described where enhancement in value due to public improvement was allowed without qualification. In some jurisdictions provisions are embodies in the state constitutions, or contained in statute law, to the effect that valuation in eminent domain shall be determined "irrespective" of benefits from or enhancement due to the public improvement for which the lands are taken. [More] | |
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6 - Standing to Sue for Purposes of Securing Judicial Review of Exercise of Administrative Discretion in Route Location of Federal-Aid Highways
1/1/1969
A SUMMARY IS PRESENTED OF RECENT DECISIONS IN THE FEDERAL COURTS SHOWING THAT CHANGES ARE OCCURRING WHICH MAY INDICATE THAT TRADITIONAL CONCEPTS OF STANDING TO SUE TO SECURE JUDICIAL REVIEW OF THE EXERCISE OF ADMINISTRATIVE DISCRETION IN RESPECT TO ROUTE LOCATION WILL NO LONGER GOVERN. A BRIEF REVIEW IS PRESENTED OF EARLY CASE LAW ON THE EXERCISE OF ADMINISTRATIVE DISCRETION IN DETERMINING ROUTE LOCATION. THE FIRST DEPARTURE FROM THE RULES LAID DOWN IN HISTORICAL CASES CAME IN ROAD REVIEW LEAGUE VS. BOYD, 270 F. SUPP. 650 (S.D. N.Y., 1967). IN THIS CASE THE COURT HELD THAT THE LANGUAGE OF THE FEDERAL POWER ACT GAVE PETITIONERS STANDING TO SUE, ALTHOUGH THEY DID NOT AND COULD NOT SHOW THAT THEIR OWN PROPERTIES WERE DIRECTLY AFFECTED OR THAT THEY WOULD SUFFER SOME ECONOMIC INJURY BY REASON OF THE ACTION TAKEN BY THE FEDERAL POWER COMMISSION. THE OPINION WAS BASED ON THE UNITED STATES CODE SECTION 702 OF TITLE 5 WHICH PROVIDES THAT A PERSON SUFFERING LEGAL WRONG BECAUSE OF AGENCY ACTION, OR ADVERSELY AFFECTED OR AGGRIEVED BY AGENCY ACTION WITHIN THE MEANING OF A RELEVANT STATUTE, IS ENTITLED TO JUDICIAL REVIEW THEREOF. CASES PERMITTING JUDICIAL REVIEW WITHOUT RESPECT TO AUTHORIZATION BY STATUTE ARE DISCUSSED. DECISIONS OF THE SUPREME COURT OF THE UNITED STATES ON STANDING TO SUE AND FEDERAL CASES DEALING WITH THE ADMINISTRATIVE PROCEDURE ACT ARE REVIEWED. IT IS HOPED THAT THIS COMMENTARY SHOULD PROVE USEFUL TO STATE HIGHWAY OFFICIALS IN UNDERSTANDING CHANGES THAT ARE OCCURRING WHICH CHALLENGE FORMERLY WELL-ESTABLISHED RULES CONCERNING STANDING TO SUE TO SECURE JUDICIAL REVIEW OF THE EXERCISE OF ADMINISTRATIVE DISCRETION IN ROUTE LOCATION. IF STATE HIGHWAY OFFICIALS UNDERSTAND THE TREND BEING ESTABLISHED AT THE NATIONAL LEVEL, THEY MAY TAILOR THEIR STATE'S HIGHWAY PLANNING PROCESSES IN A WAY TO MINIMIZE COSTLY DELAYS. [More] | |
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4 - Rigid Pavement Performance Influenced by Slab Strength and Thickness
1/1/1969
EXISTING THEORIES FOR STRUCTURAL BEHAVIOR OF RIGID PAVEMENTS WERE EXAMINED IN VIEW OF THE LARGE AMOUNT OF CONTROLLED FIELD PERFORMANCE DATA COLLECTED DURING AN AASHO ROAD TEST. A SIGNIFICANT CONTRIBUTION WAS THE DEVELOPMENT OF A RELATIONSHIP BETWEEN TENSILE STRESS IN THE PAVEMENT SLAB CAUSED BY MOVING LOADS AND THE PERFORMANCE OF PORTLAND CEMENT CONCRETE PAVEMENT. THE FINDINGS SUPPORT MOST EXISTING THEORETICAL METHODS OF RIGID PAVEMENT DESIGN AND WILL BE OF PARTICULAR VALUE IN DESIGN OF PAVEMENTS FOR RAPIDLY INCREASING TRAFFIC, HEAVIER WHEEL LOADS, AND NEW OR MODIFIED CONSTRUCTION MATERIALS AND TECHNIQUES. THE EVIDENCE OF THE RELATIONSHIP BETWEEN TRAFFIC LOADINGS AND CONCRETE SLAB STRENGTH (BASED ON PAVEMENT SLABS 2.5 TO 11 INCHES THICK AND SINGLE-AXLE LOADINGS OF 6000-30,000 LB) IS STRONG ENOUGH SO THAT FURTHER CONFIRMATION IS NOT NEEDED, BUT THAT THE NEED FOR QUALITY CONTROL DURING CONSTRUCTION IS EMPHASIZED. EXAMINATION OF THE FINDINGS INDICATE: (1) SLAB THICKNESS SHOULD BE INCREASED AS THE FIFTH ROOT OF ANTICIPATED NUMBER OF LOAD APPLICATIONS; (2) PAVEMENT LIFE VARIES AS THE FOURTH POWER OF THE CONCRETE STRENGTH; (3) A CONSISTENT 20% OVERLOAD MAY REDUCE PAVEMENT LIFE TO 1/2, AND THE APPLICATION OF ONE DOUBLE LOAD IS EQUIVALENT TO 16 APPLICATIONS OF NORMAL LOAD; AND (4) THE ANALYSES FURNISH A BASIS FOR PREDICTION OF EFFECTS OF TANDEM-AXLE LOADS WITH DIFFERENT AXLE SPACING. [More] | |
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3 - Relocation Assistance Under Chapter Five Of the 1968 Federal-Aid Highway Act
1/1/1969
A SYNOPTIC REVIEW OF CHAPTER FIVE OF THE 1968 FEDERAL-AID HIGHWAY ACT IS PRESENTED. A DISCUSSION AND COMPARISON IS PRESENTED OF STATUTES THAT HAVE BEEN ENACTED TO COMPLY WITH THE NEW RELOCATION ASSISTANCE PROVISIONS. THE RULE IS DISCUSSED THAT COMPENSATION IS FOR PROPERTY TAKEN AND NOT AS A PAYMENT TO THE OWNER, CONSTITUTIONAL AUTHORITY IS DISCUSSED AS TO PROVISIONS FOR PAYMENT IN EXCESS OF THE JUST COMPENSATION REQUIRED BY THE FIFTH AMENDMENT OF THE UNITED STATES CONSTITUTION. AN ANALYSIS IS MADE OF CONSTITUTIONAL PROBLEMS WHICH CAN BE EXPECTED BY THE STATES SECURING COMPLIANCE. SELECTED LEGAL CASES ARE PRESENTED. STATES STATUTES ENACTED TO COMPLY WITH CHAPTER FIVE ARE DESCRIBED. A PROPOSED ACT IS PRESENTED WHICH SHOULD PROVE HELPFUL IN DRAFTING LEGISLATION. [More] | |
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TRBโs Transit Cooperative Research Program (TCRP) and National Cooperative Highway Research Program (NCHRP) have jointly produced Research Results Digest TCRP 65/NCHRP 288 -- A New Vision of Mobility: Guidance to Foster Collaborative Multimodal Decision Making. The single digest summarizes the results of the first phase of a TCRP and NCHRP jointly funded project that will eventually produce a short document for popular distribution, serving as a guidance resource in a โhandbookโ format and a โcompendiumโ of case examples upon which the guidance document is based.
TRB's National Cooperative Highway Research Program (NCHRP) Research Results Digest 287: Highway Capacity Manual Applications Guidebook summarizes the contents of the 
TRB's National Cooperative Highway Research Program (NCHRP) Research Results Digest 286: Development of a Highway Safety Manual presents a summary of the results of a study that developed an annotated outline, prototype chapter, and work plan for the first edition of the Highway Safety Manual. More detailed information on the study is available in 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 285: Laboratory Determination of Resilient Modulus for Flexible Pavement Design describes test methods for measurement of the resilient modulus of hot-mix asphalt (HMA) and for measurement of the resilient modulus of unbound granular base and sub-base materials and sub-grade soils. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 284 -- Refining the Calibration and Validation of Hot-Mix Asphalt Performance Models: An Experimental Plan and Database summarizes activities designed to develop a detailed, statistically sound, and practical experimental plan to refine the calibration and validation of hot-mix asphalt performance models. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 283: Jackknife Testing -- An Experimental Approach to Refine Model Calibration and Validation summarizes efforts to develop a detailed, statistically sound, and practical experimental plan to refine the calibration and validation of performance models incorporated in the pavement design guide with laboratory-measured hot-mix asphalt material properties. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 282: Fiber Reinforced Polymer Composites for Concrete Bridge Deck Reinforcement describes the material requirements for fiber reinforced polymer composites used as internal reinforcement for concrete bridge decks and presents test procedures for evaluating these composites. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 281 - Aggregate Tests for Portland Cement Concrete Pavements: Review and Recommendations identifies aggregate tests related to the performance of portland cement concrete pavements and provides guidance on their use for evaluating and selecting aggregates for use in specific pavement applications. The information and guidance presented in this digest pertain to normal-density aggregates and may not apply to lightweight, heavyweight, or recycled aggregates. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 280: Continuing Project To Synthesize Information on Highway Problems outlines the NCHRP synthesis research process and provides a list of ongoing and completed NCHRP synthesis reports.
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 279: Making the Business Case for Translating Non-English Transportation Information provides an assessment of the benefits that could be realized through translation of non-English language transportation technical information. 
TRB's National Cooperative Highway Research Project (NCHRP) Research Results Digest 278 summarizes Accessible Pedestrian Signals: Synthesis and Guide to Best Practice. The full report is available on the Pedestrian and Bicycle Information Center Web site at 
The Transportation Research Board's National Cooperative Highway Research Program Research Results Digest 277: Review and Improvement of Existing Processes and Procedures for Evaluating Cultural Resource Significance describes information-technology solutions for improving development and use of resource inventories and historic contexts as tools for determining resource significance. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 276: Business Needs for Pavement Engineering summarizes the primary thrust areas of โbusiness needsโ for pavement engineering adopted by the American Association of State Highway and Transportation Officials (AASHTO) Joint Task Force on Pavements to help guide in identifying, evaluating, and prioritizing research problem suggestions. 
TRB's National Cooperative Highway Research Program Research Results Digest 275, Application of European 2+1 Roadway Designs, describes when a European 2+1 roadway design is likely to be effective in the United States and presents recommendations for designing 2+1 roads. A 2+1 road design has a continuous three-lane cross section with alternating passing lanes. 
TRBโs National Cooperative Highway Research Program (NCHRP) Research Results Digest 274: Quality Assurance of Structural Materials examines the state of the practice of quality assurance (QA) related to critical structural materials and components -- those for which failure poses a threat to public safety or to the integrity of the transportation system (e.g., bridge girders, bridge columns, and sign/signal/luminaire supports). 
TRB's Research Results Digest 273, Development of an Improved Roadside Barrier System--Phase I, provides a summary of the state of the art on the use of various guardrail systems, defines strengths and weaknesses of the current systems, and provides recommendations for changes to the strong-post w-beam barrier. 
TRB's NCHRP Research Results Digest 272, A Process for Selecting Strategies for Rehabilitation of Rigid Pavements, summarizes strategies for rehabilitation of rigid pavements subjected to high traffic volumes and a process to help state highway agency decision makers identify the most appropriate maintenance, rehabilitation, and reconstruction strategy for specific project conditions. 
TRB's NCHRP Research Results Digest Number 271, Determination of Insitu Material Properties of Asphalt Concrete Pavement Layers from Nondestructive Tests, presents tentative findings about the suitability of currently available nondestructive testing methods for determining relevant material properties. 
TRB's NCHRP Research Results Digest 268, Performance of Pavement Subsurface Drainage, provides a summary of the effects of subsurface pavement drainage features on the performance of asphalt concrete and portland cement concrete pavements. 