Abstract
Two adjacent loops can measure the speed of passing vehicles. Exact measurement is necessary of the time-lapse between the activation of both loops. Faults may stem from three causes, one of them being a defected loop itself. This article deals with two types of accurate detectors, viz. an analogue one for loop calibration and a digital one for measuring data. The first one was compared with a laser speedometer at the roadside. Further experiments have been planned for the next future.