Abstract: An estimate of the number of vehicles crossing a loop inductor having one or more interconnected discrete loops of the type found in vehicle detector system installations. A measuring signal follows changes in loop inductance caused by the influence of vehicles crossing the loop inductor. A vehicle count threshold value is computed by observing changes in the measuring signal caused by the first car crossing the loop. Subsequent excursions of the measuring signal between relative minima and relative maxima are tested against the threshold and a vehicle count event is registered when the differences exceed the threshold. After a predetermined count period, the number of vehicle counts is estimated from the total count events by multiplying them by an interpolation factor determined empirically from the type of loop inductor. Apparatus for perfoming the method is combined with a conventional vehicle detector system in a switch selectable apparatus for specifying vehicle detector mode or vehicle count mode.

Abstract: The device comprises: an elongate support part (4) suitable for being embedded in the path and having a low upstanding wall (17) running along the edge thereof; a plate (30) cantilevered out from the low wall (17) with its cantilevered portion being subdivided into tongues (38) by slots (39) which extend perpendicularly to the longitudinal direction of the support part (4); pressure transducers received in the support part (4) beneath said tongues (38); resilient means between the tongues (38) and the transducers; and electrical connection means (350) making connections with the pressure transducers.