Safety Effectiveness Evaluation of the Cable Rail Systems in Tennessee

Performances and safety effectiveness evaluation results of median cable barrier systems in Tennessee are presented in this paper. Twenty seven segments with at least three years of complete crash data before and after cable installations were analyzed. The segments were evaluated in terms of descriptive statistics of factors associated with median crashes whose occurrences were influenced by the presence or absence of the median cable barriers. The cable systems were also evaluated in terms of percentage safety effectiveness and confidence levels comparing before and after cable conditions. The study involved review of crash report hard copies where only 24% were found to be relevant for median cable barriers evaluation, 76% were not related. Descriptive statistics compared the percentage of a certain type of crashes, crash attributes and other elements to the total crashes before and after the barriers were installed. To evaluate the safety effectiveness, the research applied crash modeling in the form of safety performance models, and observational Empirical Bayes (EB) before and after analysis. Safety effectiveness of the installed median cable barrier systems was found to be 93% for fatal crashes, 85% for fatal and incapacitating injury crashes combined and 51% for the combination of fatal and all injury crashes all above 95% confidence level. The study also found that combined fatal and injury crashes were reduced by 21% after median cable installations while fatal crashes only were reduced by 80%. Total number of people killed or injured was reduced by 29% after installation.

• 
• Supplemental Notes:
  • This paper was sponsored by TRB committee AFB20 Roadside Safety Design.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Chimba, Deo
  • Emaasit, Daniel
  • Allen, Steve
  • Hurst, Brian
  • Nelson, Marcie
• Conference:
  • Transportation Research Board 92nd Annual Meeting
  • Location: Washington DC, United States
  • Date: 2013-1-13 to 2013-1-17
• Date: 2013

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 16p
• Monograph Title: TRB 92nd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Before and after studies; Cables; Crash injuries; Crash rates; Crash severity; Fatalities; Highway safety; Median barriers; Performance measurement
• Geographic Terms: Tennessee
• Subject Areas: Bridges and other structures; Highways; Safety and Human Factors; I85: Safety Devices used in Transport Infrastructure;

Filing Info

• Accession Number: 01476157
• Record Type: Publication
• Report/Paper Numbers: 13-0528
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 18 2013 10:10AM