Development of Adjustment Factors for HCM Sixth Edition Freeway Work Zone Capacity Methodology

The objective of this project is to validate the Highway Capacity Manual (HCM) work zone capacity methodology for urban and rural freeways in the SWIZDI states and to develop adjustment factors that produce more accurate estimates of work zone capacity, allowing for broad applicability across the region. Flow rate, speed, and vehicle classification data, as well as work zone schedule and configurations, will be used to estimate work zone capacity, discharge flow rate, and free flow speed. Work zone capacity describes a traffic facility's ability to sustain service flow rates near the operational optimum. Different methods have been used in the literature to estimate work zone capacity based on traffic volume data, including average queue discharge rate, maximum queue discharge rate, prebreakdown flow rate, and 95th percentile flow rate (Yeom et aI., 2015). In HCM Six Edition, work zone capacity is defined as the prebreakdown flow rate. As shown in Figure 2, the prebreakdown capacity is achieved around 6:20 pm before the traffic breaks down. After that, a queue discharge rate can be observed downstream of the bottleneck. In this example work zone, lower queue discharge rate and capacity are observed at the merge area around sensor 4 location. Five tasks have been identified to accomplish the research objective described in the previous section: (Task 1) Technical Advisory Committee (TAC); (Task 2) Data Collection; (Task 3) Validate HCM work zone capacity methodology for urban and rural freeways; (Task 4) Develop adjustment factors that produce accurate estimates of work zone capacity; and (Task 5) Final Report.

    Language

    • English

    Project

    • Status: Active
    • Funding: $70000
    • Contract Numbers:

      Addendum 645

      ISU Proposal 140335

    • Sponsor Organizations:

      Iowa Department of Transportation

      800 Lincoln Way
      Ames, IA  United States  50010
    • Managing Organizations:

      Iowa State University, Ames

      Center for Transportation Research and Education
      2711 South Loop Drive, Suite 4700
      Ames, IA  United States  50010-8664
    • Project Managers:

      Sprengeler, Dan

    • Performing Organizations:

      Iowa State University, Ames

      Center for Transportation Research and Education
      2711 South Loop Drive, Suite 4700
      Ames, IA  United States  50010-8664
    • Principal Investigators:

      Dong, Jing

    • Start Date: 20180401
    • Expected Completion Date: 20190731
    • Actual Completion Date: 0

    Subject/Index Terms

    Filing Info

    • Accession Number: 01656416
    • Record Type: Research project
    • Source Agency: Iowa Department of Transportation
    • Contract Numbers: Addendum 645, ISU Proposal 140335
    • Files: RiP, STATEDOT
    • Created Date: Jan 10 2018 11:39AM