Length Based Vehicle Classification on Freeways from Single Loop Detectors

Roadway usage, particularly by large vehicles, is one of the fundamental factors determining the lifespan of highway infrastructure, e.g., as evidenced by the federally mandated Highway Performance Monitoring System (HPMS). But the complexity of Weigh in Motion (WIM) and other classification stations makes them difficult and costly to maintain. Some of the classification stations employ axle counters, but the least expensive of these stations use dual loop detectors to measure vehicle length and classify vehicles based on this measurement. To date, collecting reliable length data from single loop detectors has been considered impossible due to the noisy speed estimates. Single loop detectors promise to be an inexpensive alternative to spread classification coverage to the existing count stations and existing traffic operations detector stations. By extending classification to the relatively high density of real time traffic monitoring stations in urban areas, the classification work could allow these urban traffic management systems to better monitor freight traffic within the metropolitan areas. The research seeks to develop a means to reliably classify vehicles using estimated vehicle length from single loop detectors. Single loop detectors are the most common vehicle detector, yet they are not used for vehicle classification due to the inherent noise in the individual vehicle length estimates. This work has developed a means to extract more reliable vehicle speed estimates from single loop detectors, and thus, vehicle length estimates as well. This new, reliable, single loop detector methodology for classifying vehicles based on estimated vehicle length is significant because it will provide a low cost means of collecting vehicle classification data by extending the capabilities of existing single loop detectors. There are thousands of single loop detectors on the freeways within the region served by NEXTRANS.

  • Record URL:
  • Supplemental Notes:
    • This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:


    Purdue University
    3000 Kent Avenue
    Lafayette, IN  United States  47906-1075

    Research and Innovative Technology Administration

    Office of University Programs, 1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Coifman, Benjamin
  • Publication Date: 2009-10-15


  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 142p

Subject/Index Terms

Filing Info

  • Accession Number: 01149505
  • Record Type: Publication
  • Report/Paper Numbers: NEXTRANS Project No. 003OY01
  • Contract Numbers: DTRT07-G-005 (Grant)
  • Files: UTC, TRIS, USDOT
  • Created Date: Jan 15 2010 12:39PM