Vehicle wheel passage detection device - uses piezoelectric cable inclined to axis of road and having staggered configuration

摘要

The device has a piezoelectric cable extending across the road. The cable has a section which is inclined to the axis of the road extending between two straight end sections each perpendicular to the axis of the road and having a max. length equal to the spacing between each pair of wheels of the smallest vehicle to be recorded. Pref. the device is combined with an indication loop for detecting each type of vehicle using the road. The piezoelectric cable is coupled to an electronic counter, registering the pulses caused by the passage of the vehicle wheels. A height control device using a light source and a photocell located at a given height allows a differentiation to be made between the wheels of heavy and light traffic. The device is used for traffic analysis surveys.