ALICE: AUTOMATIC LENGTH INDICATION AND CLASSIFICATION EQUIPMENT. AN EQUIPMENT FOR AUTOMATICALLY CLASSIFYING VEHICLES AND MEASURING THEIR SPEED

The system, "ALICE" uses standard commercial detector equipment to measure vehicle length, the number of and distance between axles, vehicle speed and the gap between vehicles. Two inductive loop detectors are used in tandem. The sensor configuration is less than 5.5M long and it is assumed that a vehicle's speed is constant for this distance. A crystal oscillator generates clock signals when an axle is detected, permitting time-related events to be measured as distances. The author describes a system of counters which effect the summation of unit distances measured by the clock signals, thus facilitating the measurement of vehicle and traffic parameters. Vehicle speed may also be calculated in selected units. Field trials were conducted to test the accuracy of the equipment and to judge whether it is possible to identify vehicles, automatically categorised, according to manual classifications. The initial trial demonstrated that "ALICE" measures for wheelbases compared favorable with the manufacturer's measurements, but actual length measurement was much less accurate. The differences between two-wheeled vehicles is difficult to distinguish; many private cars and light goods vehicles cannot be differentiated, and articulated vehicles should be individually classified. An overall accuracy of better than 96% is shown in various field trials, and reasons for errors are described. Possible future developments include the use of microprocessors. /TRRL/

  • Availability:
  • Corporate Authors:

    Printerhall Limited

    29 Newmart Street
    London W1P 3PE,   England 
  • Authors:
    • Nash, D D
  • Publication Date: 1976-12

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Filing Info

  • Accession Number: 00153337
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Sep 20 1977 12:00AM