To ensure that overloaded vehicles do not cause excessive damage to roads, most countries, including Australia, impose axle load limits on vehicles. Successful detection of overloaded vehicles is expected to lead to a reduction in the overall road network rehabilitation and maintenance costs.
Weighbridges have been deemed as being too costly to operate, with their fixed location allowing enforcement avoidance. Furthermore, portable static scales were regarded as too slow and cumbersome.
The resulting benefits to the community accrue from the reduced disruption to the transport industry through the selective interception of overloaded vehicles. The effects on industry using heavy vehicles would be significant in terms of reduced disruption to general operations through the process of targeting overloaded vehicles only.
Some Australian road agencies identified a potential ten-fold reduction in disruption costs utilising this process as compared with the existing static process of total interception.
Some WIM systems can automatically classify, measure dimensions (length, height and width) and weigh each vehicle as it passes at highway speed.
Some WIM systems (such as Culway) have been used in certain regions to assist with the identification of times and days of the week (overall trends) where enforcement activities can be utilised.
WIM systems can also be integrated with other systems (such as video detectors) to detect long-distance speeding, unregistered vehicles, stolen vehicles, pollution regulation breaches, and overloaded vehicles.
Applications in weighing for enforcement and detection are as follows:
- collection of vehicle load data to quantify the occurrence of overloading for compliance, policy and strategy formulation
- screening or filtering high speed WIM systems designed to improve the efficiency of more accurate static weighing systems or low speed WIM systems
- collection of GVM and IAM data for the development of enforcement strategies allowing efficient utilisation of enforcement resources
- collection of vehicle load data on a route or network level to access potential environmental impact
- development of vehicle load-based safety programs
- the protection of specific road pavements, bridges or unsound structures (load-based or otherwise) from vehicles above a pre-defined mass
- provision of an overload warning threshold
- audit of vehicle based on-board weighing systems
- reduction of static weigh-station congestion, vehicle backup and air pollution during testing
- collection of vehicle load data on specific sites to correlate with noise measurements.