System and method for weighing vehicles in motion

A weigh-in-motion (WIM) system adapted to accurately determine a weight of a moving vehicle on a roadway by measurement of vertical forces compensated by horizontal forces applied by a wheel of the vehicle to a weighing platform, the system comprising:

• (a) a base adapted to be anchored to a roadbed of the roadway;
• (b) a weighing platform mounted on said base and adapted to receive the wheel of the moving vehicle along a longitudinal axis of said platform, said platform having a length of at least 0.5 meters and less than 1.9 meters along said axis;
• (c) at least one load cell disposed between said base and said platform, and adapted to provide vertical load signals indicating vertical loads applied by the wheel on said platform;
• (d) a longitudinal differentiation mechanism, mechanically associated with said platform and said base, said longitudinal differentiation mechanism including:
• (i) a mechanical resistance-measuring unit adapted to provide a resistance to a relative horizontal movement between said base and said platform, said movement generally along said longitudinal axis, to differentiate horizontal forces produced by the wheel acting on said platform, and
• (ii) a measuring unit, associated with said resistance-measuring mechanical unit, said measuring unit adapted to make a measurement of a parameter associated with said resistance to said relative horizontal movement, and to produce an output signal relating to said measurement, and
• (e) a processing unit configured to:
• (i) receive said vertical load signals from said at least one load cell, and said output signal from said measuring unit, and
• (ii) measure a weight of said wheel on said platform by effecting a compensation for error in said vertical load signals with said output signal from said measuring unit, to produce a corrected weight signal.