The proposed research expands on the recently established deterioration curves for Montana bridges based on the National Bridge Inventory (NBI) element data with condition state (CS) inspection ratings for bridge elements. Consistent with the experience of other departments of transportation, challenges associated with this database include the narrow rating scale of CS-1 (good) through CS-4 (severe) and low percentage of bridge element areas rated as CS-2 through CS-4. The historical NBI component-level inspection data that uses ratings from zero to nine and other indicators (environment, traffic, and bridge type) will be investigated to improve the current deterioration curve prediction models.
Historical NBI component-level data has been successfully used to improve the reliability of deterioration curves by Illinois, Texas, and North Carolina departments of transportation. Texas and Utah have further refined their bridge deterioration curves by considering specific influencing factors such as maintenance and rehabilitation and surface treatments. South Carolina has concluded that overweight trucks cause exponentially increased damage for increasing truck weight. These studies demonstrate the potential for improvement to deterioration curves by considering other contributing factors, however they do not represent the climate, construction, maintenance, or bridge management practices of MDT.
The objectives of the research are to; 1) Identify significant factors affecting bridge deterioration in Montana. 2) Determine refinements, based on the identified significant factors, to the recently established deterioration curves from the Development of Deterioration Curves for Bridge Elements in Montana research project, and 3) Establish effective data collection, processing, and future research opportunities for improving the accuracy and consistency of Montana’s ability to forecast bridge deterioration.
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