Nothing-on-road bridge-weigh-in-motion used for long-span, concrete-box-girder bridges: an experimental case study

Nothing-on-road bridge-weigh-in-motion (NOR-BWIM) leverages the response of an instrumented bridge to identify various aspects of traffic information. This system circumvents many of the current issues with traditional BWIM systems, such as lane closure, expensive installation, etc. Most of the current studies are performed on short or medium-span T-beam and span-on-girder bridges. However, longer span lengths, construction methods, etc. can affect the efficacy of the NOR-BWIM. Thus, there is a need to further evaluate this technique on other bridges such as concrete-box-girder bridges with longer spans, in an effort to ascertain whether or not NOR-BWIM systems would still work effectively on such bridges. This work presents an experimental investigation conducted for a long-span concrete-box-girder bridge (144 m span). A total of 18 experimental tests were performed on the bridge. Moreover, a cost-effective sensor placement was developed for general use on similar long-span concrete-box-girder bridges. It was found that the number of axles is detectable with an accuracy of 100%. Moreover, the estimated mean-absolute-error for axle spacing, vehicle speed, and gross vehicle weight, were 4.6%, 2.6%, and 4.6%, respectively. Finally, it was also demonstrated that the developed cost-effective NOR-BWIM system is capable of lane identification and truck position detection.