The authors have developed ultrasonic vehicle identification equipment that identifies vehicles as they pass on the road. This is accomplished by recording a vehicle profile, which consists of height data gathered from reflected ultrasound. With two such devices placed 1 or 2 km apart, the travel time of vehicles between two points can be determined once they pass the second device, which prepares a second profile and compares it with those received from the first device that have yet to be identified. In order to verify the viability of measuring travel time by this method, a field test of the vehicle-identification equipment was conducted in a snowy area. The travel times reported by the vehicle-identification equipment were compared with travel times actually measured by by visually reading the license plates at the same two points where the equipment being tested was located, and the validity of this system has been confirmed. This is an effective system for measuring travel time in an environment where sufficient accuracy is not obtainable with Automatic Vehicle Identification (AVI) machines because of heavy snow, and for measurement of travel time at relatively low cost and in a simple manner.
Abstract