Table of Contents
- Administration
- Human Factors
- Operations
- Pavements
- Safety
- Structures
Introduction
This Turner-Fairbank Highway
Research Center (TFHRC) third Technical Publications Catalog is a comprehensive listing of our research documents
published from October 2006 through September 2007. The catalog includes
listings of fact sheets, flyers, product briefs, reports, summaries, and
TechBriefs, available both in print from our Federal Highway Administration
(FHWA) Product Distribution Center and online at www.tfhrc.gov/techpubcat/index.htm.
This catalog, along with its
two preceding volumes covering October 1998 – September 2003, and October 2003
-- September 2006, are indispensable transportation research resources for
engineers, transportation specialists, policymakers, information specialists,
and other interested groups. Readers can
immediately access most publications online or order a copy from the source
listed.
I hope you find this a useful addition to your reference library. Questions or comments about this publication can be directed to Martha Soneira at Martha.soneira@fhwa.dot.gov,
or (202) 493-3468.
Dennis C. Judycki
Associate Administrator
Research, Development, and
Technology
1 Administration
Directory
Organizational and
Expertise Directory (October 2007)
FHWA-HRT-07-050
The Turner-Fairbank Highway Research Center (TFHRC) is a federally
owned and operated research facility in McLean, Virginia. TFHRC is the home of
the Federal Highway Administration's (FHWA's) Office of Research, Development,
and Technology. The Organizational and Expertise Directory lists areas of specialties, and how to contact individuals.
http://www.tfhrc.gov/about/orgdirectory/index.htm
Summary
Office of Research, Development, and Technology Fiscal
Year 2006 Research Project Status Summary
FHWA-HRT-07-049
This summary presents tables and charts
which reflect the Federal Highway Administration (FHWA) Office of
Research, Development, and Technology's (RD&T) fiscal year (FY) 2006
progress in conducting the program of research identified in the Research, Development, and Technology
Performance Plan: Fiscal Year 2006-2007 (FHWA-HRT-06-037). FHWA is publishing this information as part of
its commitment to hold themselves accountable publicly for carrying out its
research plan. During FY 2006, researchers at the Turner-Fairbank Highway
Research Center (TFHRC) conducted 127 research projects that support the
Agency's strategic goals of Safety, Mobility and Productivity, Global
Connectivity, Environment, National Homeland Security, and Organizational
Excellence. Of the total number of projects, 44 were completed by FY end, and 83 projects are ongoing. Eighty
percent of the total number of projects were on schedule. For those research projects that were not on
schedule in FY 2006, delays were due to staff changes and delayed availability
of funds. Twelve projects in the original plan will not be conducted due to
lack of funds and revised priorities. Fifteen projects that were unanticipated
when the FY 2006/2007 performance plan was developed were added to the table.
These 15 projects were identified as priorities based on stakeholder input
following the passage of the Safe, Accountable, Flexible, Efficient
Transportation Equity Act: A Legacy for Users (SAFETEA-LU).
http://www.tfhrc.gov/about/07049/index.htm
2 Human Factors
Technical Reports
Enhanced Night Visibility
Series, Volume VI: Phase II—Study 4: Visual Performance During Nighttime
Driving in Fog
FHWA-HRT-04-137
Phase
II—Study 4 was part of the Enhanced Night Visibility project, a larger research
effort investigating drivers' visual performance during nighttime driving.
Study 4 helped expand the knowledge of how current vision enhancement systems
can affect detection and recognition of different types of objects during
adverse weather, specifically for fog conditions. Thirty participants were
involved in the study. A 6 by 3 mixed factorial design was used to investigate
the effects of different types of vision enhancement systems and driver's age
on detection and recognition of a pedestrian on the roadway. Subjective
evaluations also were obtained for the different vision enhancement systems.
The
analysis based on objective and subjective results revealed that the infrared
thermal imaging system is the best configuration for detecting pedestrians in
fog conditions. Halogen headlamps supplemented with ultraviolet A (UV–A) was a
better configuration for detecting pedestrians than the halogen and high
intensity discharge (HID) headlamps alone; however, the UV–A technology does
not represent a dramatic improvement over the halogen and HID headlamps used in
this research.
http://www.tfhrc.gov/safety/hsis/pubs/04137/index.htm
Enhanced Night Visibility Series, Volume XV: Phase III—Study 3: Influence of Beam Characteristics on
Discomfort and Disability Glare
FHWA-HRT-04-146
The objective of this study was to evaluate the discomfort and
disability glare produced by oncoming headlamps with varying beam intensity and
distribution. Oncoming headlamps can be visually discomforting and disabling to
drivers at night. In recent years, high intensity discharge (HID) headlamps
have raised some concern because of their increased light output and brighter
appearance than traditional halogen headlamps.
During the discomfort glare portion of this study, participants drove an
experimental vehicle at 32 km/h (20 mi/h) past stationary glare headlamps. They
were asked to rate their overall discomfort using the subjective deBoer scale.
The disability glare portion involved drivers detecting a static pedestrian
either near the road centerline or near the road edgeline while approaching
different sets of glare headlamps. It was hypothesized that there would be
significant differences in detection distance, illuminance at the driver's eye,
and discomfort glare rating across the different glare headlamp, pedestrian
position, adaptation level, and participant age combinations.
The main effect of glare headlamp was the only significant factor in the
analysis for discomfort glare. The main effects of age, glare headlamp, and
pedestrian location were all significant in the analysis for the disability
glare portion. In addition, the interaction of pedestrian location and glare
headlamp was significant. Overall, headlamps that had higher subjective
discomfort ratings were the same lamps that had worse objective disability
measures.
The conclusions of this research will be valuable to the consumer as well as
the manufacturers and designers of future headlamps in revealing how glare can
affect drivers on the road at night. This information can help guide new
designs to maximize forward visibility while minimizing glare.
http://www.tfhrc.gov/safety/hsis/pubs/04146/index.htm
Pedestrian and Bicyclist Intersection
Safety Indices
FHWA-HRT-06-125
The primary objective of this study was
to develop safety indices to allow engineers, planners, and other practitioners
to proactively prioritize intersection crosswalks and intersection approaches
with respect to pedestrian and bicycle safety. The study involved collecting data on pedestrian and bicycle crashes,
conflicts, avoidance maneuvers, and subjective ratings of intersection video
clips by pedestrian and bicycle experts. There were a total of 68 intersection crosswalks selected for the
bicycle analysis included 67 intersection approaches from Gainesville, FL; Philadelphia, PA; and Portland
and Eugene, OR.
FHWA Research Library and http://www.tfhrc.gov/safety/pedbike/pubs/06125/
Pedestrian and Bicyclist Intersection
Safety Indices
FHWA-HRT-06-130
The
primary objective of this study was to develop safety indices to allow
engineers, planners, and other practitioners to proactively prioritize
intersection crosswalks and intersection approaches with respect to pedestrian
and bicycle safety. The study involved collecting data on pedestrian and
bicycle crashes, conflicts, avoidance maneuvers, and subjective ratings of
intersection video clips by pedestrian and bicycle experts. There were a total
of 68 intersection crosswalks selected for the pedestrian analysis from the
cities of Philadelphia, PA; San Jose, CA; and Miami-Dade County, FL. The bicycle analysis included 67
intersection approaches from Gainesville, FL; Philadelphia, PA; and Portland and Eugene, OR.
Prioritization models were developed based on expert safety
ratings and behavioral data. Indicative variables included in the pedestrian safety
index model included type of intersection control (signal or stop sign), number
of through lanes, 85th percentile vehicle speed, main street traffic volume,
and area type. Indicative variables in the bicycle safety models (for through,
right-turn, and left-turn bike movements) included various combinations of:
presence of bicycle lane, main and cross street traffic volumes, number of
through lanes, presence of on-street parking, main street speed limit, presence
of traffic signal, number of turn lanes, and others. Through this User Guide,
practitioners will be able to use the safety indices to identify which
crosswalks and intersection approaches have the highest priority for in-depth
pedestrian and bicycle safety evaluations and subsequently use other tools to
identify and address potential safety problems.
FHWA Research Library and http://www.tfhrc.gov/safety/pedbike/pubs/06130/
3 Operations
Fact Sheets
NGSIM Overview
FHWA-HRT-06-135
Traffic microsimulation models are
becoming widely used and valuable tools in modeling existing and planned future
transportation networks and conditions. These models can help transportation professionals make important
decisions on such topics as new roadway alignments and configurations, new
interchange configurations and locations, the addition of freeway auxiliary
lanes, work zone management strategies and plans, operations and intelligent
transportation system (ITS) strategies and plans, coordination and timing of
traffic signals, and the addition of high-occupancy toll lanes.
FHWA Research Library and http://www.tfhrc.gov/about/06135.htm
Freeway Lane Selection Algorithm
FHWA-HRT-06-136
At the heart of the Next Generation
SIMulaiton (NGSIM) program is the development of freely available driver
behavior algorithms that represent the fundamental logic within microscopic
traffic simulation models. A
comprehensive survey of NGSIM stakeholder groups, coupled with an assessment of
existing microsimulation systems and driver behavior algorithms, revealed a
number of high-priority needs for algorithm development under the NGSIM
program. As a result, researchers
developed the Freeway Lane Selection algorithm as one of the first of several
algorithms under the NGSIM program.
FHWA Research Library and http://www.tfhrc.gov/about/06136.htm
Interstate 80 Freeway Dataset
FHWA-HRT-06-137
To support the development of
microscopic driver behavior algorithms, the Next Generation SIMulation (NGSIM)
program is collecting detailed, high-quality traffic datasets. The NGSIM datasets represent the most detailed and accurate field data collected to date for traffic microsimulation
research and development. The Interstate
80 freeway dataset was the first of several datasets collected under the NGSIM
program.
FHWA Research Library and http://www.tfhrc.gov/about/06137.htm
Evolution of a Traffic Shockwave
FHWA-HRT-07-023
This brief narrative traces the evolution of a minor, lane-specific traffic shockwave using vehicle trajectory
data from the first NGSIM dataset. This dataset tracks the exact position of all 4,733 vehicles that traversed a half mile freeway weaving section on Interstate 80 in Emeryville, California, over a 30-minute period.
FHWA Research Library
Lankershim Boulevard Dataset
FHWA-HRT-07-029
To support the development of
algorithms for driver behavior at the microscopic level, the Next Generation
SIMulation (NGSIM) program is collecting detailed, high-quality traffic
datasets. NGSIM stakeholder groups
identified the collection of real-world, vehicle trajectory data as important
to understanding and researching driver behavior at a microscopic level. The NGSIM datasets represent the most
detailed and accurate field data collected date for traffic microsimulation
research and development. The Lankershim Boulevard
dataset was one of several datasets collected under the NGSIM program.
FHWA Research Library and http://www.tfhrc.gov/about/07029.htm
US Highway 101 Dataset
FHWA-HRT-07-030
Researchers for the NGSIM program
collected detailed vehicle trajectory data on southbound US 101, also known as the Hollywood Freeway, in
Los Angles, California, on June 15, 2005. The study area was
approximately 640 meters in length and consisted of five mainline lanes
throughout the section. NG-VIDEO, a
customized software application developed for the NGSIM program, transcribed
the vehicle trajectory data from the video. This data provided the precise location of each vehicle within the study
area every one-tenth of a second, resulting in detailed lane positions and
locations relative to other vehicles.
FHWA Research Library and http://www.tfhrc.gov/about/07030.htm
Technical Report
Traffic Analysis Toolbox Volume I:
Traffic Analysis Tools Primer
FHWA-HRT-04-038
This primer provides an overview of
traffic analysis tools in the transportation analysis process. Different categories of traffic analysis
tools are defined, and the challenges and limitations of using traffic analysis
tools are presented. A specific
comparison between Highway Capacity Manual analysis and traffic simulation-based
analysis is provided. Criteria for
selecting the appropriate type of traffic analysis tool are described. A list of traffic analysis tools within each
category and their corresponding website links is provided in an appendix. This is the first volume in a series of
volumes in the Traffic Analysis Toolbox.
FHWA Research Library and http://ops.fhwa.dot.gov/trafficanalysistools/tat_vol1/vol1_primer.pdf
Traffic Analysis Toolbox Volume II:
Decision Support Methodology for Selecting Traffic Analysis Tools
FHWA-HRT-04-039
This report provides an overview of the
role of traffic analysis tools in the transportation analysis process and
provides a detailed decision support methodology for selecting the appropriate
type of analysis tool for the job at hand. An introduction to the role of
traffic analysis tools and tool categories is provided. A set of criteria for selecting the
appropriate type of traffic analysis tools is described in detail and each tool
category is scored as to its relevance to the criteria. This is the second volume in a series of
volumes in the Traffic Analysis Toolbox.
FHWA Research Library and http://www.ops.fhwa.dot.gov/trafficanalysistools/tat_vol2/Vol2_Methodology.pdf
Traffic Analysis Toolbox Volume
III: Guidelines for Applying Traffic
Microsimulation Modeling Software
FHWA-HRT-04-040
This report describes a process and
acts as guidelines for the recommended use of traffic microsimulation software
in transportation analyses. The
seven-step process presented in these guidelines highlights the aspects of
microsimulation analysis from project start to project completion. The seven steps in the process include: 1)
scope project, 2) data collection, 3) base model development, 4) error
checking, 5) compare model MOEs to field data, 6) alternatives analysis, and 7)
final report. Each step is described in
detail and an example problem applying the process is carried through the
entire document. This is the third
volume in a series of volumes in the Traffic analysis Toolbox.
FHWA Research Library and http://ops.fhwa.dot.gov/trafficanalysistools/tat_vol3/vol3_guidelines.pdf
Volume II: Enhanced Night Visibility
Series: Overview of Phase I and Development of Phase II Experimental Plan
FHWA-HRT-04-133
The focus of the Phase I effort was on the establishment of
performance and design objectives to facilitate the deployment of ultraviolet A
(UV–A) headlamps. This report describes the plan to develop UV–A headlamp specifications, evaluate fluorescent infrastructure materials, quantify glare and photobiological risks, expand the cost/benefit analysis, and demonstrate and implement the UV–A technology. It also includes a literature review that was conducted before the Phase II studies. As is often the case in large projects, some of the planned work eventually changed or was replaced to address more pressing issues. The later volumes of this report series detail what research occurred and why.
http://www.tfhrc.gov/safety/hsis/pubs/04133/index.htm
Traffic Detector Handbook: Third Edition—Volume I
FHWA-HRT-06-108
The objective of this Handbook is to
provide a comprehensive resource for selecting, designing, installing, and
maintaining traffic sensors for signalized intersections and freeways. It is intended for use by traffic engineers
and technicians having responsibility for traffic sensors, whether in-roadway
or over-roadway sensor. These two
families of sensors have different characteristics and thus corresponding
advantages and disadvantages that are discussed throughout the Handbook. Topics
covered include sensor technology, applications, in-roadway sensor design,
installation techniques, and maintenance. The sensor technology chapter discusses the operation and uses of inductive
loop detectors, magnetic sensors and detectors, video image processors,
microwave radar sensors, laser radars, passive infrared and passive acoustic
array sensors, and ultrasonic sensors, plus combinations of sensor
technologies. The sensor application
topics addresses safety, operational performance, multimodal issues, and
physical and economic factors that the practitioner should consider.
FHWA Research Library and http://www.tfhrc.gov/its/pubs/06108/index.htm
Traffic Detector Handbook: Third Edition—Volume II
FHWA-HRT-06-139
The objective of this Handbook is to
provide a comprehensive resource for selecting, designing, installing, and
maintaining traffic sensors for signalized intersections and freeways. It is intended for use by traffic engineers
and technicians having responsibility for traffic sensors, whether in-roadway
or over-roadway sensors. These two
families of sensors have different characteristics and thus corresponding
advantages and disadvantages that are discussed throughout the Handbook. Topics covered include sensor technology,
applications, in-roadway sensor design, installation techniques, and
maintenance. The sensor technology
chapter discusses the operation and uses of inductive loop detectors, magnetic
sensors and detectors, video image processors, microwave radar sensors, laser
radars, passive infrared and passive acoustic array sensors, and ultrasonic
sensors, plus combinations of sensor technologies. The sensor application topics addresses
safety, operational performance, multimodal issues, and physical and economic
factors that the practitioner should consider. Appendixes include research, background papers, and implementation
guidance. The information contained in this Handbook is based on the latest research available on treatments and best
practices in use by the surveyed jurisdictions. References are provided for the student, practitioner, researcher, or
decisionmaker who wished to learn more about a particular subject.
FHWA Research Library
4 Pavements
Flyer
LTPP
2006 Year in Review
FHWA-HRT-07-028
Improving the productivity and mobility of the national highway
transportation system are key goals of the Federal Highway Administration
(FHWA). During 2006, FHWA's Long-Term Pavement Performance (LTPP) program
worked toward these goals through its efforts to provide answers to
"how" and "why" pavements perform as they do. To better
understand pavement performance, the LTPP program gathers and processes data
describing the structure, service conditions, and performance of 2,513 pavement
test sections in North America. Highway engineers use these data and data analysis findings to help make decisions that
lead to more cost-effective and better performing pavements. This flyer describes 2006 accomplishments,
LTTP products, and lists LTTP publications for 2006, and describes the future
under SAFETEA-LU.
http://www.fhwa.dot.gov/pavement/ltpp/pubs/07028/
Newsletter
LTPP Newsletter Volume 3 , Issue 1 Winter
2007
FHWA-HRT-07-037
The latest edition of the world's largest pavement performance database is now available from the Federal Highway Administration's (FHWA) Long-Term Pavement Performance (LTPP) program. LTPP
Standard Data Release (SDR) 21 can be obtained as a five CD-ROM set or on a
single DVD-ROM. The SDR is in Microsoft® Access format.
Previously a utility software included as
part of the LTPP SDR package, ESALCalc also is now available via DataPave
Online.
Additional information included in this newsletter are TRB's annual meeting updates, and an announcement of Eric Weaver's new position.
http://www.fhwa.dot.gov/pavement/ltpp/news/07winternews.cfm
LTPP Newsletter Volume 3, Issue 2 Spring 2007
FHWA-HRT-07-047
The Federal Highway Administration (FHWA)
sponsors the Transportation Pooled Fund (TPF) Program as a way for FHWA,
interested States, and other organizations to partner when significant or
widespread interest is shown in solving transportation-related problems.
Partners may pool funds and other resources to solve these problems through
research, planning, and technology transfer activities.
TPF studies cover a wide array of topics,
from asphalt to work zones. Studies address pavement quality and composition,
traffic monitoring and management, bridge design and repair, air quality,
development of training modules, and safety for drivers, pedestrians, and
construction crews as well as fish, deer, and bats. In many cases, the pooled
fund process provides an effective mechanism to promote new technology.
Technology transfer covers activities that lead to the adoption of a new
technique or product. The TPF Program encourages States to include technology
transfer activities in all pooled fund studies, but some projects focus solely
on technology transfer.
A number of Long-Term Pavement
Performance (LTPP)-related pooled fund studies have been completed or are now
underway and are listed within this newsletter.
http://www.fhwa.dot.gov/pavement/ltpp/news.cfm
Technical Report
Long-Term Pavement Performance Program
Falling Weight Deflectometer Maintenance Manual
FHWA-HRT-05-153
The Federal Highway Administration's
Long-Term Pavement Performance (LTPP) program operates eight Dynatest Model
8000 FWDs to collect deflection data on in-service pavement test sections
across North America. LTPP has collected pavement deflection data
in daily operations for 15 years, and in that time, the FWDs have had very
little downtime. Continuous preventive
maintenance is necessary to keep the complex hydraulic-electrical-mechanical
FWDs operating under demanding conditions to collect high quality data and pass
rigorous annual reference calibrations. The owner's manual from the manufacturer provides guidance on most
repairs and troubleshooting; however, eventually FWDs require service beyond
routine maintenance--in other words, the time comes for a complete
overhaul. The LTPP Southern Region support contractor overhauled one of the FWDs operated for the LTPP
program. During the overhaul, the contractor documented the process photographically and described the process of disassembling and reassembling the FWD components and subcomponents. This document provides FWD owners, operators, and technicians' information as a supplement to the Dynatest 8000 owner's
manual. Maintenance guidelines are based
on continuous operation of FWDs.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/ltpp/pubs/05153/
Improving Pavements With Long-Term
Pavement Performance: Products for Today and Tomorrow
FHWA-HRT-06-109
This report is a compilation of
award-winning technical papers from the Third Annual International Contest on
LTPP Data Analysis 2003-2004, various authors.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/ltpp/pubs/06109/index.cfm
Long-Term Pavement Performance (LTPP)
Data Analysis Support: National Pooled Fund Study TPF-5 (013)
FHWA-HRT-06-121
The objectives of this study are to:
(1) quantify the effects of frost penetration on pavement performance in
climates with deep sustained frost as compared to environments with multiple
freeze-thaw cycles, (2) investigate the effect that local adaptations have on
mitigating frost penetration damage, and (3) estimate the associated cost of
constructing and maintaining pavements in freezing climates. The approach consisted of modeling various
pavement performance measures using both climatic and nonclimatic input
variables and performance data collected as part of the Long-Term Pavement
Performance program.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/ltpp/pubs/06121/index.cfm
Long-Term Pavement Performance Program
Manual for Falling Weight Deflectometer Measurements
FHWA-HRT-06-132
This document provides background
information and field operations guidelines for the collection of Falling
Weight Deflectometer (FWD) data on Long Term Pavement Performance (LTPP) test
sections. It includes equipment setup,
equipment calibration, test locations, and test procedures.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/ltpp/pubs/06132/index.cfm
The Use of Lithium to Prevent or
Mitigate Alkali-Silica Reaction in Concrete Pavements and Structures
FHWA-HRT-06-133
Alkali-silica reaction (ASR) was first
identified as a form of concrete deterioration in the late 1930's. Approximately 10 years later, it was
discovered that lithium compounds can be used to control expansion due to
ASR. There has recently been increased
interest in using lithium technologies to both control ASR in new concrete and
to retard the reaction in existing ASR-affected structures. This facts book provides information on
lithium, its origin and properties, and on its applications. The mechanism of alkali-silica reaction is
discussed together with methods of testing to identify potentially
alkali-silica reactive aggregates. Traditional methods for minimizing the risk of damaging ASR are
presented; these include the avoidance of reactive aggregates, controlling the
levels of alkali in concrete and using supplementary cementing materials such
as fly ash, slag and silica fume. The
final two sections of the facts book discuss the use of lithium, first as an
admixture for new concrete construction and second as a treatment for existing
concrete structures affected by ASR.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/concrete/pubs/06133/index.cfm
Advanced Quality Systems: Guidelines
for Establishing and Maintaining Construction Quality Databases
FHWA-HRT-07-019
The main objective of this study was to
develop and present guidelines for State highway agencies (SHAs) in
establishing and maintaining database systems geared towards construction
quality issues for asphalt and concrete paving projects. To accomplish this, a literature search and
review was performed on the subject matter, followed by a survey of
construction quality practices at nine States and a more detailed review of
practices at four of those nine States.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/concrete/pubs/07019/index.cfm
5 Safety
Fact Sheet
Lankershim Boulevard Dataset
FHWA-HRT-07-029
To support the development of algorithms for driver behavior at
the microscopic level, the Next Generation SIMulation (NGSIM) program is
collecting detailed, high-quality traffic datasets. NGSIM stakeholder groups
identified the collection of real-world, vehicle trajectory data as important
to understanding and researching driver behavior at a microscopic level. The
NGSIM datasets represent the most detailed and accurate field data collected to
date for traffic microsimulation research and development. The Lankershim Boulevard
dataset was one of several datasets collected under the NGSIM program.
http://www.tfhrc.gov/about/07029.htm
TechBrief
Pedestrian and Bicyclist Intersection Safety Indices
FHWA-HRT-06-129
The Pedestrian and Bicycle Intersection Safety Indices (Ped ISI
and Bike ISI) are a set of models that enable users to identify intersection
crossings and intersection approach legs that should be the greatest priority
for undergoing indepth pedestrian and bicycle safety assessment. Using
observable characteristics of an intersection crossing or approach leg, such as
number of lanes and traffic volume, the tool produces a safety index score,
with higher scores indicating greater priority for an indepth safety
assessment. Each leg of an intersection may have different characteristics
affecting pedestrian or bicyclist safety; therefore, the tool is intended to
provide a rating of the safety of an individual crossing (Ped ISI) or approach
leg (Bike ISI) rather than evaluating the intersection as a whole. A
practitioner can use the tool to develop a prioritization scheme for a group of
pedestrian crossings or bicyclist approaches. This method enables the
practitioner to prioritize and proactively address sites that are the most
likely to be a safety concern for pedestrians or bicyclists without having to
wait for crashes to occur.
http://www.tfhrc.gov/safety/pedbike/pubs/06129/index.htm
Safety Assessment of Interchange
Spacing on Urban Freeways
FHWA-HRT-07-031
In this research, we have studied the
urban freeway interchange spacing problem from a safety perspective, and we
have developed a valid fatal/injury crash prediction model using combined data
from California and Washington State for urban freeways. These models quantify the sensitivity of crash rates to interchange spacing for fatal and
injury crashes. A major value of the
model is the ability to evaluate the impact of inserting new interchanges in
existing urban freeway interchange spacings. The developed models should help decisionmakers quantify the safety
impacts while conducting the cost-benefit analysis for projects involving
construction of new interchanges or changes to existing interchanges. This evaluation is limited to freeway safety,
and it excludes consideration of impact on surface streets and their
intersections with new ramps.
FHWA Research Library and http://www.tfhrc.gov/safety/pubs/07031/index.htm
Traffic Performance of Three Typical
Designs of New Jersey Jughandle Intersections
FHWA-HRT-07-032
For this study, researchers used VISSIM
simulations to model typical geometries over a wide distribution of traffic
flow conditions for three NJJI design. Comparisons of NJJIs with conventional intersections for similar volume
conditions revealed that NJJIs produced lower average intersection delays and
higher intersection capacities for near-saturated traffic conditions and
similar traffic performance for undersaturated conditions. Practitioners can use statistical models
documented in this study to assess average intersection delays, average number
of stops per vehicle, and maximum queue lengths for three types of NJJIs.
FHWA Research Library and http://www.tfhrc.gov/safety/pubs/07032/index.htm
Synthesis of the Median U-Turn
Intersection Treatment, Safety, and Operational Benefits
FHWA-HRT-07-033
This synthesis summarizes the
advantages and disadvantages of the MUTIT compared to conventional, at-grade
signal-controlled intersections with left turns permitted from all
approaches. The synthesis presents
design guidelines including the location and design of the median crossovers on
the major roads. Many of the guidelines
presented in the synthesis are from the Michigan Department of Transportation,
and address directional and bidirectional crossovers and widened areas called
"loons" that facilitate the U-turn maneuver by larger vehicles and at roads
with narrow medians. The synthesis also
discusses application criteria for the MUTIT, and presents information on the
capacity and crash experience at these intersections relative to traditional
intersections.
FHWA Research Library and http://www.tfhrc.gov/safety/pubs/07033/index.htm
Drivers' Evaluation of the Diverging Diamond Interchange
FHWA-HRT-07-048
In recent years, the Federal Highway Administration (FHWA) has been advocating novel intersection designs as a way to promote intersection safety while meeting the often conflicting demands for increasing capacity, decreasing congestion, and minimizing the cost of new infrastructure. One of these novel designs is the diverging diamond interchange (DDI). This study suggests that, where it is adopted, the DDI will deliver safety benefits. The prospective safety benefit combined with predicted operational
benefits and reduced roadway width requirements for overpasses or underpasses
should make the DDI an attractive interchange design alternative.
FHWA Research Library
Technical Report
Software Reliability: A Preliminary Handbook
FHWA-HRT-04-080
The
overall objective of this handbook is to provide a reference to aid the highway
engineer, software developer, and project manager in software verification and
validation (V&V), and in producing reliable software. Specifically, the
handbook:
- Demonstrates the need for V&V of highway-related software.
- Introduces the important software V&V concepts.
- Defines the special V&V problems for highway-related software.
- Provides a reference to several new software V&V techniques developed under
this and earlier related projects to address the special needs of
highway-related software:
- Wrapping,
i.e., the use of embedded code to make a program self-verifying.
- SpecChekTM, a V&V tool to check software with its specifications.
- Real-time computation of roundoff and other numerical errors.
- Phased introduction of new software to minimize failures.
- Helps the highway engineer, software developer, and project manager integrate software V&V into the development of new software and retrofit V&V into existing software.
The handbook emphasizes techniques that address the special needs of highway software, and provides pointers to information on standard V&V tools and techniques of the software industry.
http://www.tfhrc.gov/safety/pubs/04080/index.htm
Enhanced Night Visibility
Series, Volume XI: Phase II—Cost-Benefit Analysis
FHWA-HRT-04-142
This volume of the Enhanced Night Visibility project is a
cost-benefit analysis of the vision enhancement system (VES) and roadway
marking technologies evaluated in the Phase II experiments of the Enhanced
Night Visibility project. The cost-benefit analysis indicates that neither the
ultraviolet-A (UV–A) headlamp nor the fluorescent pavement marking technologies
are fully developed for implementation. Under the conditions simulated in the Virginia Smart Road tests, most of the combinations of experimental VESs and experimental marking
materials show no net improvement in sight distance in comparison to the
combination of halogen (i.e., tungsten-halogen) low-beam headlamps and a
nonfluorescent pavement marking.
The best-performing VES configurations were the halogen low beam (HLB) and five
UV–A + HLB. HLB serves as the benchmark, with both its estimated crash
reduction benefit and its incremental cost defined to be zero. The slight
overall benefit of five UV–A + HLB over HLB would lead to a positive crash
savings, but its cost of implementation would result in a cost-benefit ratio of
0.001 and in negative net benefits of less than zero.
Among the pavement markings tested, the fluorescent paint generally performed
worse than the fluorescent thermoplastic. Neither of the tested fluorescent
pavement markings is forecast to generate positive benefits in comparison with
the performance of the nonfluorescent pavement marking.
http://www.tfhrc.gov/safety/hsis/pubs/04142/index.htm
Users Manual for LS-DYNA Concrete
Material Model 159
FHWA-HRT-05-062
An elasto-plastic damage model with
rate effects was developed for concrete and implemented into LS-DYNA, a
commercially available finite element code. This manual documents the theory of the concrete material model,
describes the required input format, and includes example problems for use as a
learning tool. A default material property
input option is provided for normal strength concrete. The model was developed for roadside safety
applications, such as concrete bridge rails and portable barriers impacted by
vehicles, but it should also be applicable to other dynamic applications.
FHWA Research Library and http://ntlsearch.bts.gov/tris/record/tris/01052039.html
Evaluation of LS-DYNA Concrete
FHWA-HRT-05-063
An elastoplastic damage model with rate
effects was developed for concrete and implemented into LS-DYNA, a commercially
available finite element code. This
manual documents the evaluation of the concrete material model, including the
selection of the concrete model input parameters. The model is evaluated through correlations
with test data; drop tower impact of 1/3-scale beams, bogie vehicle impact of
full-scale reinforced beams, pendulum impact of bridge rails, and quasi-static
loading of a safety-shaped barrier. Although the model was developed and evaluated for roadside safety
applications, it should also be applicable to many dynamic problems.
FHWA Research Library
Interchange Safety Analysis Tool (ISAT): User Manual
FHWA-HRT-07-045
This
User Manual describes the usage and operation of the spreadsheet-based
Interchange Safety Analysis Tool (ISAT). ISAT provides design and safety
engineers with an automated tool for assessing the safety effects of geometric
design and traffic control features at an existing interchange and adjacent
roadway network. ISAT can also be used to predict the safety performance of
design alternatives for new interchanges and prior to reconstruction of
existing interchanges. The primary outputs from an analysis include: the number
of predicted crashes for the entire interchange area, the number of predicted
crashes by interchange element type (i.e., mainline freeway segments, ramps,
ramp terminals and intersections, and crossroad roadway segments), the number
of predicted crashes by year, and the number of predicted crashes by collision
type.
This
User Manual presents basic information for getting started with using ISAT, the
general methodology that users will follow when conducting an analysis with
ISAT, input requirements of the program, default data incorporated within the
program and recommendations on when and how these default data should be updated
by the user, output reports generated by ISAT, and general information on
different applications for which ISAT can be applied. An example problem is
also provided on the safety performance of a rural diamond interchange and
surrounding roadway network, illustrating user inputs and generated output
reports.
http://www.tfhrc.gov/safety/pubs/07045/index.htm
6 Structures
TechBrief
Wind Induced Vibration of Stay Cables
FHWA-HRT-05-084
This TechBrief is a summary of the
complete report FHWA-HRT-05-083, Wind Induced Vibration of Stay Cables. At the time of the present investigation, it
was evident that the rain-wind problem had been essentially solved for
practical provisions for its mitigation. However, some further experimental and analytical work was needed to
supplement the existing knowledge base on several other stay cable vibration
issues in order to formulate adequate design guidelines. The objectives of this project were to: (1)
identify gaps in current knowledge base; (2) conduct analytical and
experimental research in critical areas; (3) study performance of existing
cable-stayed bridges; (4) study current mitigation methods; (5) develop
procedures for aerodynamic performance assessment; and (6) develop design and
retrofit guidelines for stay cable vibration mitigation.
FHWA Research Library
Freeze-Thaw Resistance of Concrete with
Marginal Air Content
FHWA-HRT-06-118
Freeze-thaw resistance is a key
durability factor for concrete pavements. Recommendations for the air void system parameters are normally 6± 1 percent total air and a spacing factor of 0.20 millimeter. However, it was observed that some concretes
without these commonly accepted thresholds presented good freeze-thaw
resistance in laboratory studies. This
study evaluated the freeze-thaw resistance of several marginal air void mixes
with two types of air-entraining admixtures, a Vinsol® resin and a synthetic
admixture. To conduct the study,
researchers used rapid cycles of freezing and thawing in plain water, with no
deicing salts.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/concrete/pubs/06118/
Guidelines for Establishing Maintaining
Construction Quality Databases
FHWA-HRT- 07-020
The primary purpose of construction
quality databases is to help State highway agencies assess the quality of
materials production and placement, including the establishment of pay factors
for quality. A secondary purpose is to
support other agency activities, including performance analysis and
improvements to current standards and specifications. These databases have become a critical
component in construction quality assurance programs. The study upon which this TechBrief is based,
Advanced Quality Systems: Guidelines for Establishing and Maintaining
Construction Quality Databases provides a detailed description of an ideal
construction quality database.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/concrete/pubs/07020/
Strengthening Historic Covered Bridges
to Carry Modern Traffic
FHWA-HRT-07-041
This document is a technical summary of
the unpublished Federal Highway Administration report, Strengthening Historic Bridges to Carry Modern Traffic. This TechBrief describes research on the use
of glass fiber reinforced polymer (GFRP) composites to strengthen wooden
superstructure components of historic covered bridges. The research was conducted during the years 2000 to 2004.
FHWA Research Library and http://www.tfhrc.gov/structur/pubs/07041/index.htm
Multiple Corrosion Protection Systems
for Reinforced Concrete Bridge Components
FHWA-HRT-07-044
This is the interim report on a Federal
Highway Administration project that is fully documented in a separate report
under the same title (FHWA-HRT-07-043). The purpose of this study is to evaluate methods for making ECR more
corrosion resistant by using multiple corrosion protection strategies in bridge
decks, as well as for bridge members in marine environments where abundant
salt, moisture, and high temperatures are prevalent.
FHWA Research Library and http://ntlsearch.bts.gov/tris/record/tris/01055102.html
Current Provisions and Needed Research
for Lightweight Concrete in Highway Bridges
FHWA-HRT-07-051
This document is a technical summary of
the unpublished Federal Highway Administration (FHWA) report, Synthesis of Research and Provisions
Regarding the Use of Lightweight Concrete in Highway Bridges which is
available only through the National Technical Information Service
(ww.ntis.gov) This TechBrief summarizes
a synthesis report on completed research and current American Association of
State Highway and Transportation Officials (AASHTO) provisions related to lightweight
concrete used in highway bridges. The
synthesis report is intended to provide a reference point for an FHWA research
program aimed at addressing perceived shortcomings in the AASHTO specifications
pertaining to lightweight concrete. The
synthesis report also makes recommendations for future research efforts,
focusing on the use of lightweight concrete in bridge structures.
FHWA Research Library and http://www.fhwa.dot.gov/bridge/pubs/07051/index.cfm
Technical Reports
Compilation and Evaluation of Results
from High-Performance Concrete Bridge Projects, Volume I: Final Report
FHWA-HRT-05-056
In 1993, the Federal Highway
Administration initiated a national program to implement the use of
high-performance concrete (HPC) in bridges. The program included the construction of demonstration bridges throughout the United States
. Other States have implemented the use of HPC
in various bridge elements. The
construction of these bridges has provided a large amount of data on the use of
HPC. This project is composed of four
parts. The first part involved
collecting and compiling information. The second part involved a review of the American Association State Highway and
Transportation Officials (AASHTO) Standard Specifications for Transportation
Materials and Methods of Sampling and Testing, and the Standard Specifications
for Highway Bridges, and the Load and Resistance
Factor Design Bridge Design Specifications and the Bridge Construction
Specifications. The third part of the
project involved the development of proposed revisions to the AASHTO
specifications. The fourth part of the
project involved the development of specific recommendations for needed
research.
FHWA Research Library and http://www.tfhrc.gov/structur/pubs/05060/index.htm
Compilation and Evaluation of Results
from High-Performance Concrete Bridge Projects, Volume II: Appendixes
FHWA-HRT-05-057
In 1993, the Federal Highway
Administration initiated a national program to implement the use of
high-performance concrete (HPC) in bridges. The program included the construction of demonstration bridges
throughout the United States
. Other States have implemented the use of HPC
in various bridge elements. The
construction of these bridges has provided a large amount of data on the use of
HPC. This project is composed of four
parts. The first part involved
collecting and compiling information. The second part involved a review of the American Association State Highway and
Transportation Officials (AASHTO) Standard Specifications for Transportation
Materials and Methods of Sampling and Testing, and the Standard Specifications
for Highway Bridges, and the Load and Resistance
Factor Design Bridge Design Specifications and the Bridge Construction
Specifications. The third part of the
project involved the development of proposed revisions to the AASHTO
specifications. The fourth part of the
project involved the development of specific recommendations for needed
research.
FHWA Research Library
Optimized Sections for High-Strength Concrete Bridge Girders--Effect of Deck Concrete Strength
FHWA-HRT-05-058
This report contains an evaluation of
the effect of high-performance concrete on the cost and structural performance
of bridges constructed with high-performance concrete bridge decks and
high-strength concrete girders. Bridge
designers and owners are the main audience.
FHWA Research Library and http://www.tfhrc.gov/structur/pubs/05058/index.htm
Users Manual for LS-DYNA Concrete Material Model 159
FHWA-HRT-05-062
An
elasto-plastic damage model with rate effects was developed for concrete and
implemented into LS-DYNA, a commercially available finite element code. This
manual documents the theory of the concrete material model, describes the
required input format, and includes example problems for use as a learning
tool. A default material property input option is provided for normal strength
concrete. The model was developed for roadside safety applications, such as
concrete bridge rails and portable barriers impacted by vehicles, but it should
also be applicable to other dynamic applications.
The
companion report to this manual is entitled Evaluation of LS-DYNA Concrete Material Model 159, FHWA-HRT-05-063.
http://www.tfhrc.gov/safety/pubs/05062/index.htm
Evaluation
of LS-DYNA Concrete Material Model 159
FHWA-HRT-05-063
An elastoplastic damage model with rate effects was developed for
concrete and implemented into LS-DYNA, a commercially available finite element
code. This manual documents the evaluation of the concrete material model,
including the selection of the concrete model input parameters. The model is
evaluated through correlations with test data: drop tower impact of
⅓-scale beams (plain and reinforced), bogie vehicle impact of full-scale
reinforced beams, pendulum impact of bridge rails, and quasi-static loading of
a safety-shaped barrier. Although the model was developed and evaluated for
roadside safety applications, it should also be applicable to many dynamic
problems.
The companion manual to this report is Users
Manual for ls-dyna Concrete Material Model 159, FHWA-HRT-05-062.
http://www.tfhrc.gov/safety/pubs/05063/index.htm
Seismic Retrofitting Manual for Highway
Structures: Part 1 – Bridges
FHWA-HRT-06-032
This report is the first of a two-part
publication entitled: Seismic Retrofitting Manual for Highway Structures: Part
1: Bridges, Part 2: Retaining Structures, Slopes, Tunnels, Culverts and
Roadways. Part 1 of this manual is based
on previous Federal Highway Administration publications on this subject including
Seismic Retrofitting Manual for Highway Bridges, published in 1995. Revisions have been made to include current
advances in earthquake engineering, field experience with retrofitting highways
bridges, and the performance of bridges in recent earthquakes. It is the result of several years of research
with contributions from a multidisciplinary team of researchers and
practitioners.
FHWA Research Library
Material Property Characterization of
Ultra-High Performance Concrete
FHWA-HRT-06-103
This report presents the results from a
large suite of material characterization tests that were completed in order to
quantify the behaviors of a commercially available UHPC. The characteristics of this UHPC under four
different curing regimes were captured. This study focused on strength-based behaviors, long-term stability
behaviors, and durability behaviors.
FHWA Research Library and http://www.tfhrc.gov/structur/pubs/06103/index.htm
Structural Behavior of Ultra-High
Performance Concrete Prestressed I-Girders
FHWA-HRT-06-115
In the past decade significant advances
have been made in the field of high performance concretes (HPC). The next generation of concrete, ultra-high
performance concrete (UHPC), exhibits exceptional tensile and compressive
strength characteristics that make it well suited for use in highway bridge
structures. Prestressed highway bridge
girders were cast from this material and tested under flexure and shear
loadings. These tests demonstrated that
UHPC can carry all shear forces normally demanded of a prestressed I-girder and
can also significantly enhance the flexural capacity of the girder. Based on this research, a basic structural
design philosophy for bridge I-girder design is proposed.
FHWA Research Library and http://www.tfhrc.gov/structur/pubs/06115/index.htm
Freeze-Thaw Resistance of Concrete With
Marginal Air Content
FHWA-HRT-06-117
Freeze-thaw resistance is a key
durability factor for concrete pavements. Recommendations for the air void system parameters are normally: 6±1
percent total air and spacing factor less than 0.20 millimeters. However, it was observed that some concretes
that did not possess these commonly accepted thresholds presented good
freeze-thaw resistance in laboratory studies. This study evaluated the freeze-thaw resistance of several "marginal"
air void mixes, with two different types of air-entraining admixtures—a Vinsol
resin and a synthetic admixture. This
study used rapid cycles of freezing and thawing in plain water, in the absence
of deicing salts. For the specific
materials and concrete mixture proportions used in this project, the marginal
air mixes presented an adequate freeze-thaw performance when Vinsol resin based
air-entraining admixture was used. The
synthetic admixture used in this study did not show the same good performance
as the Vinsol resin admixture.
FHWA Research Library and http://www.fhwa.dot.gov/pavement/pccp/pubs/06117/
Effects of Inlet Geometry
on Hydraulic Performance of Box Culverts
FHWA-HRT-06-138
Each year, the South Dakota Department of Transportation (SDDOT)
designs and builds many cast-in-place (CIP), or field cast, and precast box
culvert structures that allow drainage to pass under roadways. The CIP boxes
typically have 30-degree-flared wingwalls, and the precast have straight
wingwalls with 10.16-centimeter (cm) (4-inch) bevels on the inside edges of the
wingwalls and top slab. Previous research conducted on a limited number of
single barrel box culverts indicated that further research was necessary to
determine (1) the effects of multiple barrel structures, (2) loss coefficients
of unsubmerged outlets, and (3) the effects of 30.48-cm (12-inch) corner
fillets versus 15.24-cm (6-inch) corner fillets. In order to optimize the
design of both types of box culverts, it was also necessary to determine the
effects of span-to-rise ratios, skewed end conditions, and optimum edge
conditions on typical box culvert installations.
http://www.fhwa.dot.gov/engineering/hydraulics/pubs/06138/index.cfm
Durability of Segmental Retaining Wall
Blocks: Final Report
FHWA-HRT-07-021
Segmental
retaining wall (SRW) systems are commonly and successfully used in a range of
applications, including highway projects. Their popularity can be attributed to
a combination of reduced construction costs, versatility, aesthetic appearance,
ease of installation, and an increasing number of proprietary designs available
in the market. Despite these inherent advantages, there have been some reported
problems with durability of SRW blocks in cold climates. The deterioration of
some SRW installations in State highway agency (SHA) applications has resulted
in concern over the long-term performance of SRW systems and has led to stricter
specifications and, in some cases, restrictions on future use of SRW
systems. In response to these concerns,
a Federal Highway Administration (FHWA)-funded research project was initiated
to determine the cause and extent of SRW block distress, to identify and
recommend test methods for improving durability of SRW systems, and to
recommend specifications for SHAs to ensure long-term durability and
performance of SRW systems in highway applications. This report summarizes the
key findings of this project and provides guidance on producing durable SRW
blocks to ensure long-term performance of SRW systems in highway applications.
FHWA Research Library http://www.tfhrc.gov/structur/pubs/07021/index.htm
Flexural Capacity of Fire-Damaged Prestressed Concrete Box Beams
FHWA-HRT-07-024
A gasoline tanker truck fire caused significant damage to an
adjacent member box-beam bridge in southwestern Connecticut. It was unclear whether the type
of damage that these box beams experienced was sufficient to critically impair
the structure's ability to serve its intended purpose. Four of the beams were
removed from the bridge and were loaded in flexure to failure. These tests
indicated that each of the beams retained sufficient flexural capacity to
resist a 1,572 kilonewton-meter (kN-m) (1,160 kip-feet (kip-ft)) moment prior
to ultimate flexural failure. This value is greater than the rated ultimate
flexural capacity of each beam. As such, it seems that these beams had
sufficient remaining flexural capacity to serve their intended purpose in the
immediate aftermath of the fire. The long-term viability of these beams is more
questionable. The visual and petrographic examinations indicated that the
damage to the bottom flange concrete was sufficient to allow pathways through
the concrete to the depth of the bottom strands. Therefore, it is possible that
fire may have acted to allow for the accelerated deterioration of the
superstructure and thus decreased the long-term flexural capacity of the
bridge.
http://www.tfhrc.gov/structur/pubs/07024/index.htm
Bottomless Culvert Scour Study: Phase II Laboratory Report
FHWA-HRT-07-026
Bottomless culverts are three-sided structures that use the
natural channel for the bottom. These structures could be used to convey flows
from one side of a highway to the other. As such, they are an environmentally
attractive alternative to box, pipe, and pipe arch culvert designs. Bottomless
culverts range in size from less than a meter (1.5 feet) to more than 10 meters
(35 feet) in width. The failure of such a structure could have severe
consequences similar to the failure of a bridge. On the other hand, since the
cost of the foundation and scour countermeasures represents a significant
portion of the cost of this type of structure, overdesign of these elements can
add significantly to the cost of the project.
Several dozen physical modeling configurations of bottomless culverts were
tested, and the resulting scour at the entrance along the foundation and outlet
was measured. Predictive equations for estimating scour depth were developed
and compared to MDSHA methodology. These equations will provide guidance for
the design of footing depths for bottomless culverts.
The study was conducted in two phases. The first phase focused on measuring
maximum scour depths at the culvert entrance and developing an analysis
procedure using methods found in the literature to approximate prescour
hydraulic parameters that drive the analysis. No fixed-bed experiments were
conducted in the first phase to measure actual prescour hydraulic parameters.
No submerged entrance experiments were conducted in the first phase. The second
phase expanded the investigation to include scour measurements at the outlet,
submerged entrance scour measurements, and detailed velocity and depth
measurements with a prescour fixed bed at locations where maximum scour
occurred. Additional tests were conducted to evaluate the use of various
measures to reduce scour including wingwalls, pile dissipators, riprap, and
cross vanes.
http://www.fhwa.dot.gov/engineering/hydraulics/pubs/07026/
Junction Loss Experiments:
Laboratory Report
FHWA-HRT-07-036
The current study has two objectives. The first is to evaluate
Roger Kilgore's proposed procedure, which requires conducting some of the same
types of tests that were run in the previous study. The new tests conducted
include a wider range of parameters, such as greater plunge-height ratios and
steeper pipe slopes. Previous research was limited in that it was applicable to
storm drain systems located only in relatively flat areas; the research would
not hold up for systems in hilly and mountainous regions of the country where
steep pipe slopes are the norm.
The second and more challenging objective is to characterize the
energy level in an access hole. If that can be accomplished, then the familiar
culvert hydraulics analyses can be applied to the access hole that serves as
the tailbox where inflow pipes enter and to the headbox for outflow pipes where
the water exits. Researchers have attempted numerous analyses of particle image
velocimetry (PIV) data and three-dimensional (3–D) numerical model data, with
uneven results. Characterizing energy in the access hole is highly problematic
because the flow is so chaotic, and arbitrary assumptions had to be made to
obtain results that fall between intuitive limits.
Researchers at the FHWA lab now have investigated the more
organized flow in the contracted area of the outflow pipe, using the
contraction ratio as an indirect measure of the contraction loss in the flow
from the access hole to the outflow pipe to backcalculate the energy loss in
the access hole.
http://www.fhwa.dot.gov/engineering/hydraulics/pubs/07036/index.cfm
Corrosion Resistant Alloys for
Reinforced Concrete
FHWA-HRT-07-039
The present research study is being performed jointly by Florida Atlantic University and the Florida Department of Transportation to evaluate alloys that have been identified as candidate corrosion resistant reinforcements. These include MMFX-XX&153;, solid stainless steels 3Cr12, 2201DX, 2205, and two 316L alloys; and two 316 stainless steel clad black bar products. Black bar reinforcement was included for comparison purposes. Testing methods included three types of short-term exposures: (1) a previously developed method that involves cyclic exposure to synthetic pore solution (SPS) with incrementally increasing chlorides and then to moist air, (2) anodic potentiostatic exposure in SPS with incrementally increasing chlorides, and (3) potentiodynamic polarization scans in saturated Ca(OH)2 at different chloride concentrations. This report details findings for the initial 3 years of this 5 year project.
FHWA Research Library and http://www.fhwa.dot.gov/bridge/pubs/07039/
Multiple Corrosion Protection Systems for Reinforced Concrete Bridge Components
FHWA-HRT-07-043
Eleven systems combining epoxy-coated reinforcement with another corrosion protection system are evaluated using the rapid macrocell, Southern Exposure, cracked beam, and linear polarization
resistance tests. The systems include bars that are pretreated with zinc chromate to improve the adhesion between the epoxy and the reinforcing steel; two epoxies with improved adhesion to the
reinforcing steel; one inorganic corrosion inhibitor, calcium nitrite; two organic corrosion inhibitors; an epoxy-coated bar with a primer containing microencapsulated calcium nitrite; the three epoxy-coated bars with improved adhesion combined with the corrosion inhibitor calcium nitrite; and multiple coated bars with an initial 2-mil coating of 98 percent zinc and 2 percent aluminum followed by a conventional epoxy-coating. The systems are compared with conventional
uncoated reinforcement and conventional epoxy-coated reinforcement. The results presented in this report represent the findings obtained during the first half of a 5-year study that includes longer-term ASTM G 109 and field tests. In the short-term tests used to date, the epoxy-coatings evaluated provide superior corrosion protection to the reinforcing steel. The results also
indicate that the bars will continue to perform well in the longer term, although the tests do not evaluate the effects of long-term reductions in the bond between the epoxy and the reinforcing steel.
FHWA Research Library and http://www.fhwa.dot.gov/bridge/pubs/07043/