ANALYSIS OF ROAD NETWORKS RESILIENCE IN SIMULATED SCENARIOS OF SEISMIC EVENTS

One of the main functions of road networks is to allow accessibility to land areas characterized by human settlements and sensitive points of interest. In the case of bridge disruption or collapse, as it may occur during seismic events, the robustness of road networks and the related resilience performance can mitigate negative impacts, due to the role of alternative routes in providing the required connectivity. In this framework, to prevent the impact of seismic events it is necessary to have adequate forecasting models. This paper explores a methodology, based on the graph theory, according to the availability of input data and datasets. Moving from a simple topology-based approach, where only the basic connectivity information is used, an accessibility analysis is conducted, extending the dataset with speed information for links to a functional approach, based on the service provided by the road infrastructure, in which the traffic flow data are required and the link capacity may enhance the accuracy of estimates. Methodologies based on simulation and publicly available data have the aim of easily transferring and replicating the analysis in other areas. As preliminary operations, bridge identification and classification are performed to map critical network elements, which are integrated into the road network model provided by public authorities. Moving from the information dataset resulting from the recently adopted Italian guidelines for the analysis of the safety performance of existing bridges, critical scenarios are generated and compared covering potential seismic events in the study area of the Turin Metropolitan Area to evaluate the vulnerability of the road network by applying GIS and traffic simulation tools. Results can be applied in the planning processes to rank critical facilities, not only in terms of local risk assessment but also in terms of network performance.