Because serious problems result from using vehicle detectors on or in the pavement, a better method of traffic data collection in high-speed and/or high-capacity areas is needed. Also, working conditions for personnel have become hazardous. Therefore, through the advances in sensor technology, a new product has been developed to circumvent these problems. This paper presents the results of a study to develop an overhead vehicle sensor system. Through careful evaluation, a prototype using an infrared sensor system was constructed and tested extensively. However, it was discovered that this design was too complicated for use as a remote-vehicle sensor. Therefore, a new design using an ultrasonic ranging system was evaluated and implemented. Prototypes were constructed and tested in the laboratory and in the field, and this design was accepted as being highly suitable for use as an overhead vehicle sensor.
Abstract