Abstract
Suburban arterial roadways must serve two conflicting road functions: regional mobility and access to the abutting land. The potential for conflicts between traffic passing through and traffic accessing road from the neighboring areas could raise safety concerns. Selecting an adequate cross-section is among important decisions that road designers and traffic engineers consider when mitigating the mentioned conflict. The following three alternative treatments offer different access control levels: undivided cross-section with no median, two-way left-turn lane instead of a typical median, and non-traversable median. The frequency of access points and the selected median treatment option should be commensurate.
Although it is known that access control usually leads to better safety performance, selecting a median treatment and under certain operational conditions requires careful consideration that must be associated with a properly selected speed limit. It is a challenging task not well covered in the existing literature. Drivers’ perception of crash risk affects their speed choice and, consequently, the speed limits selected by traffic engineers. On the other hand, the posted speed limits affect both drivers’ speed selection and road safety. Properly estimating this complex relationship is important for providing adequate guidance on median treatment selection.
To properly compare the safety performance of different median treatments on suburban arterial roads and to provide practical median treatment selection guidance for traffic engineers, this study analyzed roadway geometrics, traffic and crash data along 200 road segments across Indiana by applying simultaneous equations to address the endogeneity problem mentioned earlier. A comprehensive crash cost-oriented analysis framework was applied to help identify the most appropriate median treatment among the three types evaluated.
Traffic volume, density of access points, speed limit, and median treatments on the road segments studied were found to significantly affect safety performance. It was also confirmed that the operational conditions affect the crash cost and, consequently, they influence the choice of the median treatment. The study results were used to generate a convenient set of tables and figures to support a median treatment selection. The results presented and implementation suggestions are meant to help end users economically assess the safety performance of median treatments on suburban arterials to select the best alternative.
Keywords
median, suburban arterial, safety performance, median treatment
Report Number
FHWA/IN/JTRP-2025/07
SPR Number
4736
Sponsoring Organization
Indiana Department of Transportation
Performing Organization
Joint Transportation Research Program
Publisher Place
West Lafayette, Indiana
Date of Version
2025
DOI
10.5703/1288284317848
Recommended Citation
Tarko, A. P., Guo, Q., Narayanan, P. D., Romero, M. A., & Bandaru, V. K. (2025). A study of suburban arterial safety performance based on median type (Joint Transportation Research Program Publication No. FHWA/IN/JTRP-2025/07). West Lafayette, IN: Purdue University. https://doi.org/10.5703/1288284317848
SPR-4736 Technical Summary