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A Benefit/Cost Analysis of Paved Shoulder Installation on High Priority Road Segments on Two-Lane Rural Highways in Alabama




Ayala, Renee

Type of Degree



Civil Engineering


There are currently more than 40,000 deaths a year that occur as the result of motor vehicle traffic accidents, which have been ranked among the leading causes of death for Americans. In addition, a reported 55% of all roadway fatalities are the result of roadway departures. In an effort to reduce the number of accidents that occur on two-lane rural highways the Alabama Department of Transportation established a new policy in 2006 to begin installing 2-ft of paved shoulders on both sides of the highways during resurfacing and reconstruction projects. This type of countermeasure provides an additional recovery area for vehicles that have veered out of the traveled way as well as a reduction in accidents. Since the policy that ALDOT established in 2006 has only been in effect for two years, a before-and-after study to quantify the benefits of installing 2-ft paved shoulders was not possible. However, a hypothetical benefit/cost analysis was needed to evaluate the potential benefits and lay the foundation for future research in this area. As part of this analysis a detailed methodology was created to assist in the identification of high priority segments that could experience a significant reduction in accidents if this treatment were implemented. The CARE 8 software program that has been developed and maintained by the University of Alabama CARE Research and Development Laboratory was used to conduct a high accident analysis. Based on this analysis, two different lists of high priority segments were created which contained accident and location information for the top 5% of the road segments that were identified based on two criteria: crash rate and severity. The economic benefits associated with the installation of paved shoulders at these locations were calculated based on a range of crash reduction factors. The cost of installing 2-ft paved shoulders was determined based on 41 projects that had already been let to bid by ALDOT. The resulting benefit/cost ratios for the high priority segments in each of the criteria ranged from 0.08:1 to 2.20:1 for the segments identified based on crash rate and 1.22:1 to 8.18:1 for those segments identified based on severity. The results of this preliminary analysis indicated that the installation of 2-ft paved shoulders on two-lane rural highways in Alabama is a cost effective countermeasure that has the potential to significantly reduce accidents and improve safety.