Socio-economic effect of seismic retrofit of bridges for highway transportation networks: a pilot study

Abstract A simulation-based study is performed to evaluate the socio-economic effect of seismic retrofit of bridges using the California Department of Transportation (Caltrans) Los Angeles area highway network as the testbed. 47 scenario earthquakes that represent the regional seismic hazard, consistent with the US Geological Survey (USGS) hazard map, are considered. Two sets of bridge fragility curves, before and after seismic retrofit, are used to simulate the seismic performance of the network in both cases. Analysis estimates the total social cost arising from driver delay and loss of opportunity in the degraded network. The benefit of seismic retrofitting is computed in present values as equal to the total future economic losses avoided from social cost and repair/restoration cost over the remaining bridge service lives. Estimated benefit is compared with the retrofit cost to investigate the benefit-cost ratio. Study shows that from the Caltrans point of interest, bridge seismic retrofit is cost-effective when loss avoided due to social cost is considered. Keywords: highway transportation systemseismic retrofitdriver delayloss of opportunityeconomic analysisbenefit-cost ratio Acknowledgements This study was partially supported by California Department of Transportation (Caltrans) under contract RTA-59A0304 and by Federal Highway Administration under contract DTFH61–98-C-00094 through the Multidisciplinary Center for Earthquake Engineering Research (MCEER) in Buffalo, NY.