Uncertainties in Seismic Risk Assessment of Highway Transportation Systems

The paper aims to assess the uncertainty involved in the estimated seismic risk of highway transportation systems. For this purpose, the highway transportation network in the area of Los Angeles and Orange County in California is considered. A set of USGS hazard-consistent future earthquakes are used that approximately represent the regional seismic hazard. Post-earthquake network damage is assessed through the predictive simulation of damage states of all highway bridges under these future earthquakes. An integrated traffic assignment model is utilized to evaluate the post-event performance of the network in terms of social cost arising from driver delay and opportunity loss. Seismic risk curves are developed that show the annual exceedance probabilities of various levels of total social cost in the network due to future seismic events. Uncertainty associated with these seismic risk curves is then investigated by quantifying uncertainties involved in various components of the risk assessment framework. Such investigation is extremely important for a reliable evaluation of system risk under extreme natural hazards.