ABSTRACT
For accurate structural assessment of bridges, detailed information on traffic loads is required, preferably at the location of the bridge. Regular Weigh-in-Motion (WIM) stations are able to measure the axle loads, axle distances and velocity for every passing vehicle. However, WIM stations are seldom present close to the bridge that is to be assessed. Therefore, the actual traffic loads on the bridge remain uncertain. As a solution, Bridge Weigh-in-Motion (BWIM) systems have been developed. In a BWIM system, measurements on the bridge are used to estimate the axle loads and other vehicle parameters. The developed BWIM system described in this paper focuses on bridges typical for the motorways in The Netherlands. The system thus needs to operate with multiple lanes in which multiple vehicles are present at the bridge simultaneously. The system is divided in several components with specific tasks, such as calculating velocity and estimating axle weights. By using sensors on different type of elements of the bridge, these tasks can be fulfilled optimally. The modularity of this system can be used to optimize new to be installed BWIM systems or to utilize an arbitrary set of already available measurements to estimate the traffic load. Depending on the sensor layout, detailed (e.g. axle loads) or more general (e.g. vehicle load) information about the traffic loads can be obtained. Results of the BWIM stations can be used as input for assessment of the bridge. This paper describes the developed BWIM system as well as a validation of the system using strain measurements of known vehicles. A comparison between BWIM and a conventional WIM system shows the potential of the BWIM system.
