Abstract: A WIM system and method for weighing a moving vehicle on a roadway, the system including: (a) a base for anchoring to a roadbed; (b) a weighing platform mounted on the base and adapted to receive the wheel of the vehicle along a longitudinal axis of the platform, the platform having a length within a range of 0.5 to 1.90 meters along the axis; (c) a load cell disposed between the base and platform, and adapted to provide vertical load signals indicating vertical loads applied by the wheel on the platform; (d) a longitudinal differentiation mechanism, mechanically associated with the platform and the base.