MPC
Research Projects (2004-05)

Identifying Number

MPC-250

Project Title

Interactive Effects of Traffic- and Environmental-Related Pavement Deterioration

University

North Dakota State University and University of Wyoming

Project Investigators

Dr. Denver Tolliver, NDSU
Dr. Khalid Ksaibati, UWY

External Project Contact

N/A

Project Objective

The specific objectives are: (1) create an integrated Region 8 pavement, traffic, and environmental database that encompasses both cross-sectional and time-series measurements; (2) formulate statistical models of pavement deterioration consistent with engineering and environmental theory; (3) estimate the models and provide interpretation of parameter estimates and hypothesis tests; (4) assess the precision and predictive capabilities of the models; and (5) illustrate uses of the models in highway planning and pavement management.

The set of potential explanatory variables includes traffic, environmental, and interaction terms. For example, average annual solar radiation and minimum monthly temperature are two environmental factors that may affect cracking and loss of PSI. In a regression model, these variables will be interacted with truck axle loads or ESALs. The interaction terms will capture the interactive effects, while the environmental and traffic variables capture the independent effects. The partial derivatives of the function will describe the overall influence on each traffic and environmental factor.

Project Abstract

Although much is known about pavement deterioration, the interactive effects of traffic and environment are difficult to quantify. The AASHTO design guide recommends that PSI loss attributable to soil swelling and frost heaving be projected for the design period and added to the projected loss in PSI from truck traffic. This approach implies that the causes of deterioration are independent and can be summed. However, this is an unrealistic assumption for some types of deterioration. As a pavement ages, traffic, moisture, and temperature interact to determine the rate of deterioration.

Previous researchers have modeled the separate effects of traffic and environment on pavements, providing a library of invaluable research. However, to fully understand the process of pavement deterioration in cold-weather climates, it is necessary to model the interactive effects. This is difficult to do with mechanistic-empirical models. Moreover, accelerated road tests don't account for the time-dependent interactions of traffic and environment. The overall objective of this project is to comprehensively model pavement deterioration for the cold-weather climates of Federal region 8 using regression analysis.

Task Descriptions

1. Perform literature review including SHRP studies
2. Develop databases from LTPP and time-series HPMS data
3. Analyze and validate the data for purposes of statistical analysis
4. Formulate and estimate regression models
5. Perform regression diagnostics and re-estimate models if necessary
6. Develop report and model documentation

Milestones, Dates

Starting Date: July 1, 2004
Ending Date: June 30, 2005

Yearly and Total Budget

$86,357

Student Involvement

Two doctoral students (1 full time and 1 part time)

Relationship to Other Research Projects

None

Technology Transfer Activities

A comprehensive Region 8 database that can be used in future studies; Predictive statistical models that can be incorporated into highway planning or pavement management systems; and Documentation of data and modeling issues that may prove useful in a follow up national study.

Potential Benefits of the Project

The results of the study will: (1) improve our understanding of the interactive effects of environment and traffic in cold-weather climates, (2) provide estimates of the proportion of pavement deterioration attributable to various factors, and (3) provide maximum life values by pavement type, structural rating, and traffic levels for climatic zones and states. The project will demonstrate the desirability of conducting a broader national study, and provide insights into potential data and statistical issues.

Knowledge of the contributions of environment and traffic to pavement deterioration is necessary to accurately forecast future highway investment needs. Consequently, the results of this study may be useful in highway planning and pavement management. For example, the Highway Economic Requirements System (HERS) forecasts the deterioration rates of pavements as a result of traffic and environment. The results of this study may be useful to HERS or other highway planning models. Moreover, the results may be useful to state transportation department professionals developing or using pavement management systems.

TRB Keywords

Pavement performance