Federally required state department of transportation (DOT) Transportation Asset Management Plans (TAMPs) must include a process for risk management analysis. State DOTs are tasked with prioritizing bridges for preservation, rehabilitation, and replacement within available budgets. Investment strategies result from evaluating various levels of funding to achieve targets for bridge condition and performance effectiveness at a minimum practicable cost while managing risks. Risks include those associated with performance due to extreme events and bridge conditions. While probabilistic data, methods, and tools exist to quantitatively assess the response of bridges to extreme events using system-wide data (e.g., fragility curves), equivalent approaches for condition-related risks remain underdeveloped. Addressing this gap requires a clearer understanding of the mechanisms and circumstances that lead to unplanned bridge postings and closings due to bridge conditions. Unplanned postings and closings related to conditions may result from different causes, including (1) discovery of severe deficiency affecting strength or stability, (2) substantial change in condition since the previous inspection or due to accelerated deterioration, and (3) degradation from normal traffic or environmental loading on compromised members. These situations may be more prevalent in certain bridge types and materials (e.g., timber), component or element types (e.g., truss), element defect types (e.g., corrosion, fatigue), site locations (e.g., wet vs. dry), and so forth. Research is needed to develop procedures and tools for state DOTs to quantify the likelihood of unplanned bridge postings and closings as a function of bridge condition and defining attributes.
