An earthquake rapid warning system for railway bridges

In Italy, railway networks are highly spread and often connect densely populated urban centers and historical cities more effectively than road networks, playing a key role in everyday economic and social life. However, the whole Italian territory is prone to seismic hazard and the seismic risk of Italian critical infrastructures, such as railway networks, is of increasing research interest. The seismic risk of railway networks can be efficiently reduced through emergency management strategies that leverage earthquake warning systems to reduce the social and economic losses induced by the seismic events. Alternative methodologies and applications of warning systems exist, and one of the main differences is the length of the time window in which the warning is issued. In an earthquake early warning system, alerts are issued before the damaging seismic waves reach the protected site. Conversely, rapid warning systems conduct damage estimations immediately after the earthquake occurs to mitigate potential subsequent losses associated with unsafe network operation or unnecessary service interruption. This study develops a railway rapid warning system which is applied to a case study viaduct managed by the Ente Autonomo Volturno (EAV) agency, in southern Italy. Particular attention is dedicated to the decisional stage of the warning protocol that involves an economic-loss minimization strategy based on a multi-cost analysis, which accounts for the urban context and includes the structural damages and the environmental consequences. The system, implemented as a prototype, is able to inform about the viaduct state by updating a dedicated web page, and/or sending e-mail and SMS. The provided information includes the estimation of the damage level induced by an earthquake, and the identification of the seismic risk mitigation actions to be activated.