The Washington State Department of Transportation (WSDOT) dual-loop detector's capability of measuring vehicle lengths makes the dual-loop detection system a potential real-time truck data source for freight movement study. However, a previous study found the WSDOT dual-loop detection system was not consistently reporting accurate truck volumes. (Truck volume estimates by basic length category are developed from the vehicle length measurements produced by the dual-loop detectors.) The problems included under-count, over-count, and misclassification. As an extension of the previous study, this research project investigated and identified possible causes of dual-loop miscount and misclassification under uncongested traffic conditions. A quick remedy method was proposed to improve the performance of the dual-loop detection system without replacing any part of the current system hardware or software. A new dual-loop algorithm that can tolerate erroneous loop actuation signals was also developed to improve the performance of the WSDOT dual-loop detection system. The improved dual-loop detection system will provide reliable and timely truck volume data. WSDOT will benefit from this work by gaining more reliable volume and vehicle classification data without having to resort to any other traffic detection technologies.

  • Record URL:
  • Supplemental Notes:
    • This research was sponsored by a grant from the U.S. Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    TransNow, Transportation Northwest

    University of Washington, Department of Civil Engineering
    129 More Hall, Box 352700
    Seattle, WA  United States  98195-2700

    Department of Transportation

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Zhang, X
    • Nihan, N
    • Wang, Yinhi
  • Publication Date: 2005-2


  • English

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 194 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00989191
  • Record Type: Publication
  • Report/Paper Numbers: TNW2005-02,, Final Technical Report
  • Files: UTC, NTL, TRIS, USDOT
  • Created Date: Apr 12 2005 12:00AM