The NCDOT manages approximately 13,500 bridges across the state bridge inventory, including about 1,500 bridges considered structurally deficient which require an estimated cost of $3.8 billion to repair or rehabilitate. Currently, NCDOT relies on the Bridge Deterioration Model (BDM) to select bridge preservation projects, which is a system-wide estimation approach based on an overall bridge distribution profile. The BDM is neither suitable to determine the preservation priority according to individual bridge element conditions, nor does it consider social or economic impacts to enable a holistic approach to the asset management of existing bridges. NCDOT Structures Management Unit (SMU) and Division engineers need a tool to determine the triggering criteria for bridge preservation activities and to prioritize preservation projects based on individual bridge conditions to provide the lowest overall lifecycle cost, the best return on investment, and more value to local businesses and the public.
Bridge Criticality Levels
The proposed research will develop a tool to assist NCDOT SMU and Division engineers to determine the triggering criteria for preservation activities and prioritize weight-restricted bridge project preservation. The research will include six tasks. After a comprehensive literature review on the methods and factors used for bridge preservation project prioritization by state and federal agencies (Task 1), the research team will interview SMU and division experts and establish a database including the trigger criteria and associated preservation activities (Task 2). This research will then use the Structure Element Scores from Structure Safety Reports and the cost database for preservation activities from SMU to develop candidate preservation activities, calculate the equivalent annual cost of preservation activities, and determine the optimum preservation plan (Task 3). A cost estimation model summarizing the total budget for each bridge will be established in Task 4. Task 5 will develop a two-stage cost-benefit tradeoff model to evaluate the cost and overall impact on local business based on GIS analysis of bridge criticality to freight routes. In this framework, preservation activities will be prioritized for bridges that have heavy freight use and inefficient detours. Finally, a report and user manual will be developed in Task 6.
This research results will assist NCDOT in making informed decisions for bridge preservation actions based on individual bridge conditions, and effectively utilizing limited funding to address bridge preservation needs considering comprehensive factors.
