Final Results of the 2002 International Contest on LTPP Data Analysis

University students and professors were invited to participate in the International Contest on LTPP Data Analysis, co-sponsored by the American Society of Civil Engineers (ASCE) and the Federal Highway Administration (FHWA). The contest, now in its third year received 11 papers. It is designed to encourage students and professors from around the world to get involved in using the LTPP database. The contest creates an opportunity for students and professors to use this significant database for research, class projects, and Master's and Doctoral theses. This year students entered the contest on their own or with other students in either the undergraduate or graduate category, or partnered with a highway agency or industry group. There was also a separate category for professors to submit course curricula developed using the LTPP data.

Contest Award Ceremony

The 2001-2002 LTPP International Data Analysis Contest Award Ceremony was held at the ASCE National Meeting in Washington, DC November 3-7, 2002. Attendees included award winners Yuhong Wang, University of Kentucky, and Haleem Salem, University of Idaho. Click here for pictures of the event.

Contest Categories and Prizes

The papers were evaluated using the following criteria:

Usefulness of product and potential benefit to end users.
Originality of concept, demonstrated use of the LTPP database.
Organization of paper, and presentation (including clarity and style).

The following describes the four award categories:

Category 1, Undergraduate Students (Individual or team entry)

Teams consisted of up to three undergraduate students. The analysis was restricted to using data available on the DataPave CD-ROMs. The principal author was a student who primarily conducted the analysis.

Category 2, Graduate Students (Individual or team entry)

Teams were formed of up to three students, including undergraduate students. The principal author was the graduate student who primarily conducted the analysis.

Category 3, Partnership

This category was for undergraduate or graduate students working in partnership with a state highway agency and/or private organization/industry. The teams consisted of up to three students, not including partners. The principal author was the student who primarily conducted the analysis.

Category 4, Curriculum

This category was designed to encourage college/university professors to develop an appropriate curriculum using the LTPP database.

This Year's Winners

UNDERGRADUATE CATEGORY:

No entries this year

GRADUATE CATEGORY:

Prize	Name	Faculty Advisor
1st Place	Hassan M. Aly Salem	Fouad M. Bayomy, PE Professor of Civil Engineering University of Idaho
1st Place	Yuhong Wang	Donn E. Hancher Department of Civil Engineering University of Kentucky
2nd Place	Shameem Dewan	Roger E. Smith, Ph.D., P.E. Associate Professor CE/TTI, 503G Texas A&M University
2nd Place	Mohammed Zulyaminayn	Roger E. Smith, Ph.D., P.E, Assoc. Professor Department of Civil Engineering Texas A & M University
3rd Place	Christopher Raymond	Dr. Ralph Haas, Dr. Susan L. Tighe and Dr. Leo Rothenburg Department of Civil Engineering University of Waterloo

PARTNERSHIP CATEGORY:

No entries this year

CURRICULUM CATEGORY:

1st Place, Neeraj Buch and Karim Chatti

This year's winners will receive cash prizes and the first place winners will be recognized at this year's ASCE National Meeting in November 2002.

Abstracts of the Winning Papers

Effect of Seasonal Moisture Variation on Subgrade Resilient Modulus,
Hassan M. Aly Salem
First Place, GRADUATE CATEGORY

It is well known that environmental changes have severe effects on pavement performance. While an asphalt layer may be more sensitive to temperature, a soil or untreated pavement layer would be more affected by the change in moisture. This research aims at quantifying the effect of subgrade moisture variation, caused by environmental changes, on subgrade's resilient modulus and including its effects in the design process for new and rehabilitated pavements. To achieve this objective, data representing different soil types in non-freeze zones at various LTPP-SMP sites were downloaded from the DataPave 3 software. The downloaded data were analyzed to establish the effect of subgrade moisture variation on subgrade's resilient strength represented by the backcalculated elastic modulus. The analysis indicated that the moisture in the subgrade layer is related to the rainfall intensity. The study also revealed that a Seasonal Adjustment Factor (SAF) could be used to shift the subgrade modulus from a normal season to another. The SAF is considered a key input in the mechanistic-based pavement design system. It allows the inclusion of the seasonal effects on the layer moduli for different seasons. In this paper, a method for calculating the SAF for the subgrade soils is presented. Using the collected data, regression analysis was performed and correlation equations were developed. These equations relate the backcalculated subgrade modulus to the subgrade moisture content and other soil properties. The SAF relates the change in the moisture content to the change in the modulus value.

Development of a Pavement Climate Map Based on LTPP Data,
Yuhong Wang
First Place, GRADUATE CATEGORY

It has long been recognized that climate factors have important influences on pavement performance. To help investigate this influence, the Strategic Highway Research Program (SHRP) long-term pavement performance (LTPP) research has been using on-site or virtual weather stations to record climate information on test sections. The data will facilitate the study of the quantitative relationship between climate and pavement performance. This paper discusses how to develop a climate map using cluster analysis on performance related climate data from the LTPP database, which contains nearly 1,000 virtual weather stations recorded in more than 17 years. The aim of developing this map is to help researchers, who are performing data analysis on the LTPP database, to incorporate or separate climate factors in their models. Another potential use of this map is to help highway practitioners get climate pattern information for their geographical areas so that they can apply the same design criteria, construction requirements, and maintenance strategies to those regions with similar climate patterns.

Transforming LTPP Distress Information for use in MTC-PMS,
Shameem A. Dewan
Second Place, GRADUATE CATEGORY

The severities, types and definitions of surface distresses used in the SHRP database for LTPP sites are not the same as those used in the MTC-PMS system. Therefore, to use the LTPP distress data as inputs in the MTC-PMS software, the LTPP data must be transformed to match the MTC-PMS distress definitions. The objective of this paper is to describe a method to complete such transformations. Data conversion and use of converted data as inputs in the MTC-PMS was performed to develop a model for IRI as a function of pavement condition information, and the IRI model was intended for use in estimating user costs/benefits in the pavement management system. The condition information includes all MTC distress-severity combinations transformed from LTPP data, and corresponding deducts, percent load related deducts, percent non-load related deducts, and PCI values calculated using MTC-PMS software. The paper first presents the differences in definitions of distresses and severities in the two systems. It describes the selection of appropriate LTPP distress types to be transformed to generate required MTC distress data. Then the data transformation techniques for different distress types and severities from the LTPP system to the MTC system are explained. It was found that several types of manipulations were required to conduct the transformation of different distresses. These manipulations were performed based on the differences in definition for distresses and severities in the two systems. An IRI model was finally developed using the transformed distress data and the output from MTC-PMS software.

Adjusting Family Performance Curve for Individual Pavement Sections in Texas Department of Transportation,
Mohammed Zulyaminayn
Second Place, GRADUATE CATEGORY

A Visual Basic computer program for adjustment of the family performance curves in making reasonable predictions of individual pavement section performance has been developed under this study. The methodology formulated under Texas Department of Transportation (TxDOT) research project no. 0-4186 has been followed to adjust the family performance curves. It is assumed that pavement layer information and date of construction are known. Therefore, the appropriate performance curve, along with its basic curve modifiers ", D and $, can be selected from the family of performance curves. When the observed pavement performance data does not match with the family performance curve, the parameter P in the performance equation is to be varied to adjust the performance curve. This adjustment is considered for each category of pavement distress separately. The computer program has been tested using field data from Long-Term Pavement Performance Project (LTPP) collected on TxDOT highway sections. The predicted '5- year-ahead' distress condition and the remaining service life in terms of the distress have also been calculated for individual pavement sections.

Analysis of Influences on As-Built Pavement Roughness in Asphalt Overlays,
Christopher M. Raymond
Third Place, GRADUATE CATEGORY

Pavement roughness immediately after construction is a key measure of quality. The use of smoothness specifications requires an understanding of the influences on as-built roughness for both transportation agencies and contractors. This paper uses data from the Long-Term Pavement Performance (LTPP) program to examine four factors to determine their effects on the as-built roughness of a pavement. These factors include the extent of surface preparation prior to resurfacing, overlay thickness, type of overlay material and pavement roughness prior to resurfacing. Various statistical procedures including paired data analyses, regression analyses and a repeated measures analysis are performed to investigate these effects and any interactive effects. The extent of surface preparation, overlay thickness and pavement roughness prior to resurfacing are determined to have statistically significant effect (at a 95 percent significance level) on the as-built roughness of a pavement either directly or interactively with another variable. The overlay mix type is determined not to have an influence on as-built pavement roughness. Data from the Canadian Long-Term Pavement Performance (C-LTPP) program is used to validate the results for overlay thickness and pavement roughness prior to resurfacing. A series of prediction equations are also developed to allow for estimating the as-built roughness of a pavement under various conditions. Pavement designers, construction engineers and contractors should understand the effects that influence the as-built roughness of a pavement so that they can maximize their designs, smoothness specifications and/or bidding of contracts with smoothness specifications.

The Use of the LTPP Database in the Pavement Engineering Curriculum at Michigan State University,
Neeraj Buch and Karim Chatti
First Place, Curriculum CATEGORY

In this paper the authors demonstrate the inclusion of the Long-Term Pavement Performance (LTPP) data within the pavement-engineering curriculum at Michigan State University (MSU). The paper presents two examples, one from an undergraduate course on pavement rehabilitation and one from a graduate course on pavement analysis and design. The design examples illustrate the use of LTPP data in computing pavement responses, predicting traffic, developing rehabilitation strategies and predicting pavement performance for both rigid and flexible pavements.