Method and system for measuring the speed of a vehicle

The invention relates to a method of measuring the speed of a vehicle, using at least three acoustic transducers which are grouped together such as to form at least a first and second pair of transducers, said first and second pairs of transducers defining respectively first and second median planes which are perpendicular to the common axis. The inventive method comprises the following steps, namely: a step (70) consisting in detecting first and second instants of passage, at which the vehicle crosses the first and second median planes respectively, from the noise measured by the first and second pairs of transducers respectively; and a step (74) consisting in establishing the speed of the vehicle at least from the time between the first and second instants of passage and the distance separating the corresponding first and second median planes.