Analysis of Past National Bridge Inventory Ratings for Predicting Bridge System Preservation Needs

A bridge management system (BMS) needs an analytic tool that can predict preservation needs based on the deterioration process of bridges and answer what-if questions. Pontis software was developed to serve this purpose. Because of its intensive data requirement, Pontis has not been fully implemented by the Louisiana Department of Transportation and Development (LaDOTD). Although LaDOTD has initiated a project to collect the Pontis element data, the project will take several years to complete. An innovative approach was developed using readily available National Bridge Inventory (NBI) data in Pontis to evaluate the long-term performance of the bridge system under various BMS alternatives. The deterioration process of three NBI elements was studied, and element deterioration models were developed. Bridge preservation plans and associated cost schemes were defined according to current LaDOTD practice and available information. Findings indicate that using NBI data for BMS analysis with Pontis is not only feasible but also practical. While waiting for the completion of the Pontis database, LaDOTD can use readily available NBI data to analyze and evaluate the long-term performance of the bridge system under various budgetary and operating scenarios. Initial results indicate that LaDOTD's current annual budget of $70 million is sufficient to meet the needs of only bridge preservation, not functional improvement. If implemented successfully, the bridge preservation plan can maintain the system in good operating condition for a long time with a limited annual budget.