Understanding the Impacts of Work Zone Activities on Traffic Flow Characteristics

What effect does work activity have on traffic conditions in a work zone? This question has still not been answered satisfactorily in practice. Without knowing the true effect a work activity has on traffic, practitioners are forced to make assumptions while scheduling work. This report attempts to answer this question by studying the traffic flow characteristics for various work activities, i.e., traffic speed versus flow curves, capacity reduction factors, and free-flow speed reduction factors. The importance of the speed-flow curves and reduction factors for work zone planning is also stressed in the latest edition of the Highway Capacity Manual (HCM). The HCM recommends capacity and speed reduction factors for work zones yet does not include specific guidance for including the impact of work activities. Three traffic stream models, Gipps, Newell-Franklin, and Van Aerde, were calibrated using field data from St. Louis, Missouri. The Van Aerde model offered the best fit with the field data compared to the other two models. Using the Van Aerde model-generated speed-flow curves, it was found that the capacity for bridge-related activities varied from 1,416 vehicles per hour per lane (vphpl) to 1,656 vphpl and for pavement-related activities from 1,120 vphpl to 1,728 vphpl. The capacity reduction factor for different work activities was found to be in the range of 0.68 to 0.95, while the free-flow speed reduction factor was found to be in the range of 0.78 to 1.0. The methodology proposed in this report allows the incorporation of work activity effects into traffic impact assessment tools and results in quantitative guidance for work zone planning and design.


  • English


  • Status: Completed
  • Contract Numbers:


  • Sponsor Organizations:

    Midwest Transportation Center

    Iowa State University
    2711 S Loop Drive, Suite 4700
    Ames, IA  United States  50010-8664

    Smart Work Zone Deployment Initiative

    ,   United States 

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Managing Organizations:

    Iowa State University, Ames

    Institute for Transportation
    2711 South Loop Drive, Suite 4700
    Ames, Iowa  United States  50010-8664
  • Performing Organizations:

    University of Missouri, Columbia

    Department of Civil Engineering
    Columbia, MO  United States  65211
  • Principal Investigators:

    Edara, Praveen

  • Start Date: 20160401
  • Expected Completion Date: 20171231
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01618248
  • Record Type: Research project
  • Source Agency: Midwest Transportation Center
  • Contract Numbers: DTRT13-G-UTC37
  • Files: UTC, RiP
  • Created Date: Dec 1 2016 10:36AM