Investigating Safety Impact of Edgelines on Narrow, Rural Two-Lane Highways by Empirical Bayes Method

Narrow, rural two-lane highways are mostly characterized by low design features, light traffic volumes with high crash rates, and particularly high fatal crash rates. About 5,000 mi of these highways are administered by the Louisiana Department of Transportation and Development. Run-off-roadway (ROR) crashes are the most common type of crashes on narrow, rural two-lane highways. Because the Manual on Uniform Traffic Control Devices does not require edgelines, edgelines are not found on many such highways because of their low traffic volumes. There are two main concerns for edgeline implementation on narrow two-lane highways: the potential increase in head-on collisions and the added maintenance cost to the already constrained annual maintenance budget. The second part of a study that evaluated the safety impact of edgelines on narrow, rural two-lane highways in Louisiana is presented. On the basis of data collected from 10 locations, the first part of the study proved that edgelines centralized the lateral position of vehicles. This second part of the study evaluated the safety performance before and after the implementation of edgelines on roadway segments selected from all Louisiana districts. By using the empirical Bayes method, the study showed that edgeline implementation significantly reduced expected crash frequencies. Edgeline implementation reduced ROR crashes as well as head-on crashes. The implementation of edgelines benefited primarily male drivers and young drivers. Because of the crash-decreasing trend observed in the 3-year period classified as the after period in this study, the final estimated crash modification factor was 0.85 with a standard deviation of 0.039. The high benefit–cost ratio strongly supports edgeline implementation on narrow, rural two-lane highways in Louisiana.

• Record URL:
  • https://doi.org/10.3141/2433-14
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9780309295215
• Authors:
  • Sun, Xiaoduan
  • Das, Subasish
  • Zhang, Zhongjie
  • Wang, Fan
  • LeBoeuf, Charles
• Publication Date: 2014

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 121–128
• Monograph Title: Geology and Properties of Earth Materials 2014
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 2433
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Before and after studies; Benefit cost analysis; Crash modification factors; Crash rates; Edge lines; Frontal crashes; Highway safety; Ran off road crashes; Rural highways; Two lane highways
• Uncontrolled Terms: Empirical Bayes method
• Geographic Terms: Louisiana
• Subject Areas: Design; Geotechnology; Highways; Materials; Pavements; Safety and Human Factors; I20: Design and Planning of Transport Infrastructure; I82: Accidents and Transport Infrastructure;

Filing Info

• Accession Number: 01514509
• Record Type: Publication
• ISBN: 9780309295215
• Report/Paper Numbers: 14-1831
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Feb 18 2014 5:21PM