In this study, five field tests were conducted to determine the feasibility of using commercially-available infrared light-beam sensors for counting, classifying, and perhaps weighing vehicles. It was demonstrated that a single, reflex-type infrared sensor mounted just off the shoulder and working off a retro-reflective raised pavement marker in the center of the outside traffic lane can be used to count the tires on one end of each axle of a moving vehicle with accuracy comparable to human observers or to a flush-mounted piezo-strip sensor. Sensor installation involved no pavement cuts and only minimal interference to traffic. Tests were not conducted in snow or heavy rain. Arrays of two or more infrared light-bean sensors can be used to sense vehicle-body presence, to calculate vehicle speed, axle spacing, and tire-contact patch dimensions, to indicate single or dual tires, to detect direction of vehicle movement, and to sense over-height vehicles. Off-shoulder reflex-type infrared sensors with retro-reflective raised pavement markers operated for up to three months without cleaning. A two-sensor array tested in the Houston high-occupancy-vehicle (HOV) lane indicated promise as a replacement for loop-detector arrays. Infrared sensors can supplement weigh-in-motion systems by indicating off-transducer vehicle tires, but correlations between infrared light-beam sensor measurements and weight were not sufficient to make adequate weight estimates from such measurements practicable.

  • Supplemental Notes:
    • Research study title: Infrared Detectors for Counting, Classifying, and Weighing Vehicles.
  • Corporate Authors:

    University of Texas, Austin

    Center for Transportation Research, 3208 Red River Street
    Austin, TX  United States  78705

    Texas Department of Transportation

    Transportation Planning Division, P.O. Box 5051
    Austin, TX  United States  78763

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Garner, J E
    • Lee, C E
    • Huang, Liysheng
  • Publication Date: 1990-12


  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 80 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00625038
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/TX-91+1162-1F, Res Rept 1162-1F, CTR 3-10-88/0-1162-1F
  • Contract Numbers: Study 3-10-88/0-1162
  • Created Date: Oct 5 1993 12:00AM