The article surveys the available options for above-ground technologies concerning road vehicle detection, which are becoming increasingly important due to the problems of underground magnetic loop detectors. The outstanding advantage of above-ground detectors is their minimal ongoing cost of maintenance. Their installation is relatively inexpensive on multiple-lane high-speed roads with existing overhead structures. The options for above-ground detection include: (1) active infrared, where a stream of coded infrared, with typical wavelength 0.8-1.1 micron, is emitted onto a road surface, and a receiver examines the reflected signal; (2) passive infrared, which is sensitive to wavelengths, typically 8-14 micron, which are naturally broadcast by the targets; (3) ultrasonic, emitting ultrasonic waves which are reflected by targets; (4) CCD cameras, which are imaging systems operating in visible light or near infrared; (5) Doppler radar, which seeks small frequency shifts of radar reflected from moving targets; and (6) FMCW radar, which emits frequency modulated radar signals. In the UK and Belgium, Doppler radars have been used widely instead of loop detectors. Typical applications include: (1) pedestrian detection; (2) incident detection; and (3) traffic counts, speed estimation, and classification. Loop sensors are still best for detecting stationary vehicles. For the covering abstract see IRRD 877920.

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  • Corporate Authors:

    UK and International Press

    120 South Street
    Dorking, Surrey RH4 2EU,   England 
  • Authors:
    • Bullimore, E D
  • Publication Date: 1996


  • English

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Filing Info

  • Accession Number: 00723053
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Jul 26 1996 12:00AM