Risk-based bridge inspection practices

Improving bridge safety, reliability, and the allocation of bridge inspection resources are the goals of the proposed risk based bridge inspection practices. Currently, most bridges in the United States are inspected at a fixed calendar interval of 24 months, without regard to the condition of the bridge. Newer bridges with little or no damage are inspected with the same frequency as older, more deteriorated bridges thus creating inefficiency in the allocation of inspection resources. Because of limited resources, it is not possible to spend the necessary time examining bridges that are in poor condition and require extra attention since equal effort is also spent on bridges in good condition. In addition, no quantitative evidence exists to suggest that the 24 month inspection interval is the appropriate interval to achieve the desired level of safety. The proposed methodology incorporates reliability theory and expert elicitation from the Indiana Department of Transportation\u27s Risk Assessment Panel, developed during this research, to rationally determine bridge inspection needs. Assessments are made based on the likelihood and consequence of failure for specific bridge components. The likelihood of failure is determined through attributes based on design, loading, and condition characteristics while the consequence of failure is based on expected structural capacity, public safety, and serviceability. By combining the expressions of likelihood and consequence for each component, an optimum inspection interval for the entire bridge can be determined through the use of risk matrices. The methodology was evaluated through case studies involving Indiana bridges. Over 30 years of historical inspection reports were utilized in the back casting process to evaluate deterioration levels and assess the adequacy of the risk criteria. Results of the case studies conducted during the research indicated that the risk analysis procedures provided suitable inspection intervals ranging from 24 to 72 months for Indiana bridges