Method and system for detecting with laser the passage by a vehicle of a point for monitoring on a road

A detection system for detecting the passage of a vehicle past a determined point for monitoring a road, comprising a transmitting and receiving device disposed at a remote location for:

• (1) transmitting at least one laser beam substantially continuously to the point for monitoring, (2) receiving reflections from the at least one transmitted laser beam, and (3) determining from the received reflections that a vehicle is passing the point for monitoring,
• wherein the transmitting and receiving device is adapted to transmit at least two substantially parallel laser beams and to determine the moment of passing of the point for monitoring by said vehicle by comparing the received reflections from the various laser beams,
• further wherein the transmitting and receiving device is adapted to determine a time profile of the vehicle from a number of successively received reflections of a laser beam, and to accept a detection that the vehicle is passing the point for monitoring as valid only if the profiles determined from reflections of the various laser beams correspond precisely.