Weigh-In-Motion


Weigh-in-Motion (WIM) is the technology of weighing vehicles while they are travelling at full highway speed. There are several kinds of sensors, most of which are embedded in a groove cut into the road pavement. WIM data is used for pavement and bridge assessment, freight transport studies and, increasingly for enforcement of overloaded vehicles. Prof OBrien was the founding President of the International Society for Weigh-in-Motion and is a recognised world leader in all aspects including procurement, calibration, quality control and the applications of WIM data.

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Bridge Weigh-in-Motion

Bridge WIM is the process of using an existing bridge as a weigh scale to find the axle and gross vehicle weights of passing vehicles. Bridge WIM has been shown to be similar in accuracy to other methods of collecting WIM data but much more durable as the entire process can be done without access to the road surface. Bridge WIM data can be used for any purpose but, when the bridge itself is of interest, it can provide additional data about the bridge behaviour such as the degree of load sharing between beams. Further, a Bridge WIM system can be used to monitor the bridge as any reduction in bridge stiffness manifests itself as an apparent increase in the average weights of passing vehicles. Prof OBrien was part of the original European ‘WAVE’ research project in the 1990’s that led to the commercial Bridge WIM systems being used around the world today.

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