The value of visual inspections for emergency management of bridges under seismic hazard

One of the major problems in the aftermath of an earthquake is the management of the emergency inspection operations. Traffic restriction, including limited emergency operations or bridge closure due to safety concerns, may be issued to keep an appropriate level of safety. Visual inspections may be conducted to provide useful information on the damage state of the bridge and support the decision of imposing traffic restriction up to the complete closure of the bridge, or for allowing the immediate use of safe bridges after the event. The cost related to the inspection shall be at least balanced by the uncertainty reduction provided by the inspection data and the benefit is higher when the costs associated with taking a wrong management decision are high, but may be negligible if this is not the case. Practical tools and methods to forecast this benefit before collecting the information exist in classical decision theory, but are seldom applied by engineers. In this paper a framework based on the concept of Value of Information (VoI) from the pre-posterior Bayesian decision analysis is adopted and applied to the case study of a two span reinforced concrete bridge.