Improving Passing Lane Safety and Efficiency

Field data collected in the passing lane sites shows several important characteristics. The speed in the right lane are consistently higher than the operating speed just upstream from the passing lane. Most importantly, and for both sites, the difference in average speed between vehicles in the right lane and left lane was lower than 3 mph at both locations along the passing zone. Such operations characteristics clearly show a need for intervention measure to slow traffic in the right lane to allow for a safer passing maneuvers. The crash analysis for 67 passing lanes segments identified a total of 137 crashes occurred either at the passing lane segments or at the merging areas downstream of the passing lane. The analysis covered a 10-year period from 2005 to 2015. Of these crashes, 46.15 percent were property damage crashes, 15.38 percent were possible injury crashes, 23.08 percent were visible injury crashes, 13.94 percent were serious injury crashes, and 1.45 percent were fatal crashes. Only 9 of the 137 crashes (6.57 percent) involved alcohol use. The majority of passing lane crashes occurred during clear weather conditions (62.04 percent) and during daylight (76.64 percent). Only 8.03 percent of the crashes occurred during ice/snow conditions. Speeding, improper lane-use, and improper overtaking were the major contribution factors in 84.67 of the crashes. The average crash rates (crash/million vehicle-mile/year) for merging segments, non-merging segments, and passing lane segments are 2.316, 2.228, and 2.271, respectively. While the merging segments, downstream of the passing lanes, have slightly higher crash rates than non-merging roadway segments (3.8 percent higher), the difference is not statistically significant at the 95% confidence level.


  • English


  • Status: Completed
  • Funding: $24788.00
  • Contract Numbers:

    RP 222

  • Sponsor Organizations:

    Idaho Transportation Department

    P.O. Box 7129, 3311 West State Street
    Boise, ID  United States  83707-1129
  • Project Managers:

    Jennings, Brent

  • Performing Organizations:

    University of Idaho, Moscow

    Office of Sponsored ProgramsNational Institute for Advanced Transportation Technology
    P.O. Box 443020
    Moscow, ID  United States  83844-3020
  • Principal Investigators:

    Abdel-Rahim, Ahmed

  • Start Date: 20130107
  • Expected Completion Date: 20150930
  • Actual Completion Date: 20150930
  • Source Data: RiP Project 33237

Subject/Index Terms

Filing Info

  • Accession Number: 01560832
  • Record Type: Research project
  • Source Agency: Idaho Transportation Department
  • Contract Numbers: RP 222
  • Files: RIP, STATEDOT
  • Created Date: Apr 23 2015 1:00AM