Semester of Graduation

Spring 2022


Master of Science in Civil Engineering (MSCE)


Civil and Environmental Engineering

Document Type



The cost of TIMED (Transportation Improvement Model for Economic Development) projects were recently estimated in an economic cost-benefit analysis project currently in progress for the Louisiana DOTD. Aside from the initial construction costs, changes in user and crash costs in the future must be calculated for this task. The use of accurate crash rates is critical to this assessment's correctness. This thesis addresses the issue of estimating future crash rates of TIMED highway projects. These crash rates will be utilized in the economic analysis of the TIMED project to obtain more accurate measurement. Crash rates were determined on route US 61 and US 171. The HPMS (Highway Performance Monitoring System) and the Louisiana Department of Transportation and Development’s (DOTD) Crash databases were utilized for this study. These databases contain information on ADT, length of the road section, urban/rural category, time of crash occurrence, and several other items of information. The weighted mean crash rates were calculated by utilizing the information about ADT, length of road section and the number of crashes for each severity level (PDO, Injury, and Fatal). The crash rates were determined for each roadway classification (2-lane rural, 2-lane urban, 4-lane rural, 4-lane urban) for each crash severity (PDO, Injury, and Fatal). The highest fatal crash rate of 2.99 crashes per 100 million vehicle miles of travel, , injury crash rate of 195.57, and PDO crash rate of 424.57 were determined in the US 61 rural 2-lane category, US 171 urban 4-lane category, and US 171 urban 4-lane category, respectively. Crash rates on urban and rural roads were compared for each lane configuration and crash severity, and were found to be significantly different from each other at the 95 percent level of significance. The relationship between crash rates and the posted speed limit was also investigated using linear regression analysis. The analysis revealed that it is difficult to determine the impact of posted speed limits on crash rates only because crash rates vary widely within each posted speed interval, negating their effect on crash rates. Finally, time series analysis was employed to forecast future crash rates based on historical data. Crash rates by roadway classification and crash severity were forecast for 20 years. It was found that the injury and the PDO crash rate for the US 171 Urban 2 lane category and the fatal crash rate for the urban 4-lane category showed an increasing trend. Crash rates in all the other categories were found to have a decreasing trend. This finding paves the way for further study into the impact that vehicular technological advancements may have in reducing future crashes.



Committee Chair

Wilmot, Chester G.



Available for download on Wednesday, March 14, 2029