Austroads defines WIM as a device that measures the dynamic axle mass of a moving vehicle to estimate the corresponding static axle mass. That is, the WIM device captures and records the axle or axle group mass, hence GVM as the vehicle is moving.
WIM systems should not be confused with on-board vehicle weighing systems. On-board weighing systems are mounted or attached to the vehicle, while WIM systems are independent of the vehicle being weighed.
WIM systems fall into two broad groups:
- low speed (less than or equal to 15 km/h)
- high speed (greater than 15 km/h).
Stationary or low speed WIM systems using load cells have long been used to monitor vehicle or axle loads at weighbridges for compliance to legislation on mass limits.
The research in the last three decades has been largely on high speed WIM systems installed on road, measuring vehicles in the traffic stream.
This website content relates to high speed, permanent WIM.
Vehicle mass and relevant information collected from WIM systems can be applied in:
• asset management and pavement design
• road safety and enforcement
• freight management
• traffic management and network operations.