Transportation Infrastructures Exposed to Seismic Risk: Evaluation of Social Costs for Resilience Design

Seismic risk assessment and management of civil infrastructure systems are prominent topic for researchers. Different methods and approaches were proposed in the past and in this study, a methodology to evaluate social cost due to reduction or loss of serviceability of road network caused by catastrophic event as the liquefaction phenomenon, was developed. The strategy involves the combination of hazard, vulnerability and exposure of the transportation network by means of geotechnical and traffic analyses. The methodology was applied to the Municipality of Terre del Reno (Italy), that in 2012 was hit by a strong seismic sequence which caused severe liquefaction phenomena on the territory. Five different seismic events with increasing seismic intensity were simulated and, according to the damage level occurred, a grade of serviceability to the road network, was assigned. For each scenario, a traffic analysis, to evaluate the travel time, was performed and the social cost in terms of Over Delay Cost were evaluated. The results show an increasing Over Delay Cost as the seismic intensity increases, until the isolation of the Municipality, when a reduction was observed. It can be due a huge amount of daily trips forcibly suppressed. Although the methodology refers to damage caused by liquefaction phenomena, it is simply adaptable to any catastrophic event.