Doctor of Philosophy (PhD)


Civil and Environmental Engineering

Document Type



This study was conducted to identify and quantify the factors affecting highway crash severity in Louisiana. Three candidate models were fit to the crash data to compare their performance and the Ordered Mixed Logit (OML) model was selected as the crash severity prediction model of choice. The factors contributing to crash severity identified by the OML model are: age and gender of the driver, vehicle speed, whether alcohol played a role in the crash, whether seatbelts were used, whether the driver was ejected from the vehicle, whether the crash was a head-on collision, whether an airbag was deployed, and whether one of the vehicles was following too close behind another vehicle. Among the nine contributing factors, alcohol involvement, seatbelt use, and speed are most readily altered by a safety policy or countermeasure. Thus, a detailed analysis was conducted to analyze the impact of these factors on crash severity since they lend themselves to alteration. The following conclusions were presented by the study: for every ten percent drop in alcohol-related crashes, 4.5 % fewer fatalities and 8.7 % fewer serious injuries were predicted to occur. Proportionally, the reduction in fatalities was 5 times higher among young male drivers than the rest of the population; a 10 percent increase of seatbelt use can lead to an 8.4 percent reduction of fatal crashes and more than 6 percent decline of severe injury crashes. Targeting young male drivers and uninsured drivers would be conceivably more efficient in terms of effort per driver than applying countermeasures to all drivers; reducing the maximum speed can greatly reduce fatal crashes whereas reducing average speed can reduce the fatal and all injury crashes. The characteristics of the repeat DUI offenders and the repeat crash takers were also analyzed in the study. Based on the analysis results, safety policies and countermeasures such as a point system were identified to remedy the existing safety problems and reduce the overall crash severity. How to estimate the benefit of a safety policy is addressed at last.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Wilmot, Chester