Bridge weigh-in-motion (BWIM) technology takes the instrumented bridge as a large sensor to identify axle weights and gross vehicle weights of passing vehicles.Generally,BWIM technology takes the mid-span influence line (IL) as a reference to identify axle weights.Therefore,to obtain an IL which is close to the actual condition of the instrumented bridge is substantially important for improving the accuracy of axle weight identification.Commercial BWIM systems usually assume the IL along the transversal direction of the bridge to be identical,and the bridge is considered as a one-dimensional structure.It is reasonable for the case that the bridge deck is not wide and the number of bridge girder is less.However,when the bridge deck is wide and composed of large number of girders,the successful application of BWIM technology in this type of bridge needs further investigation.