Development and use of a GIS database for the evaluation of uncoated weathering steel highway bridge performance

Kaur, Dhilvinder
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University of Delaware
Uncoated weathering steel (UWS) has been used in the United States for highway bridge construction since 1964. Thus there is now a significant population of these bridges that have been in service for an extended period of time and it is desirable to evaluate their long-term performance. In furtherance of this goal, first a national UWS inventory was created by compiling quantitative data from the National Bridge Inventory (NBI) for the UWS bridges and associating environmental variables that may affect UWS performance (including atmospheric chemical concentrations, climate characteristics, and geographical parameters) to each bridge location using geographic information systems (GIS). This database describing the environmental conditions and corresponding performance of nearly 10,000 bridges allows for a comprehensive and quantitative description of the UWS bridge population. The next phase of research involved selecting a subset of bridges from this national inventory for further consideration for more detailed evaluation, including field evaluations. To accomplish this, a statistically driven process was created and implemented to form a matrix of bridges that contains single-parameter variations of potentially influential environmental variables, where the environments of interest focused on coastal locations and overpasses over heavily-salted, high volume roadways. The third component of this research was to develop a process for analyzing the performance of the selected bridges, based on compiling data from the owner's inspection reports. Those reports along with information in the national UWS inventory can ultimately be used to inform conclusions regarding the performance of UWS bridges.