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                Safety Effectiveness of Intersection Left and Right Turn Lanes
FHWA-RD-02-089.pdf (1.49 MB)
      
  Publication Information
                  Publication Type:Report
                  Publication Number:FHWA-RD-02-089
              Abstract:This report presents the results of research that performed a well-designed before-after evaluation of the safety effects of providing left- and right-turn lanes for at-grade intersections. Geometric design, traffic control, traffic volume, and traffic accident data were gathered for a total of 280 improved intersections, as well as 300 similar intersections that were not improved during the study period. The types of improvement projects evaluated included installation of added left-turn lanes, added right-turn lanes, and extension of the length of existing left- or right-turn lanes. An observational before-after evaluation of these projects was performed using several alternative evaluation approaches. The three contrasting approaches to before-after evaluation used were the yoked comparison or matched-pair approach, the comparison group approach, and the Empirical Bayes approach.

The research not only evaluated the safety effectiveness of left- and right-turn lane improvements, but also compared the performance of these three alternative approaches in making such evaluations. The research developed quantitative safety effectiveness measures for installation design improvements involving added left-turn lanes and added right-turn lanes. The research concluded that the Empirical Bayes method provided the most accurate and reliable results. Further use of this method is recommended.
              Publishing Date:July 2002
                          NTIS:PB2011108513
                          Publishing Office:Office of Safety Research and Development
                  FHWA Program(s):Safety
              Research
              AMRP Program(s):Safety Data and Analysis
              FHWA Activities:Highway Safety Information System
              Subject Area:Safety and Human Factors U.S. DEPARTMENT OF TRANSPORTATION

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