Intercity networks constitute a highly important civil infrastructure in developed countries, as they contribute to the prosperity and development of the connected communities. This was evident after recent strong earthquakes that caused extensive structural damage to key transportation components, such as bridges, overpasses, tunnels and geotechnical works, that in turn led to a significant additional loss associated with the prolonged traffic disruption. In cases of seismic events in developed societies with complex and coupled intercity transportation systems, the interdependency between citizens' life and road functionality has further amplified the seismically-induced loss. Quantifying therefore, the resilience of road networks, defined as their ability to withstand, adapt to, and rapidly recover after a disruptive event, is a challenging issue of paramount importance towards holistic disaster risk mitigation and management. This study takes into account the above aspects of network resilience to earthquake loading and establishes a comprehensive, multi-criterion framework for mitigating the overall loss expected to be experienced by the community due to future earthquake events. The latter is decoupled into the direct structural damage-related loss and the indirect loss associated with the travel delays of the network users, as well as the wider socioeconomic consequences in the affected area. In order to reflect the multidimensional nature of loss, a set of novel, time-variant indicators is herein introduced, while cumulative indicators are proposed for assessing the total loss incurred throughout the entire recovery period. This probabilistic risk management framework is implemented into a software to facilitate informed decisions of the stakeholders, both before and after a major earthquake event, thus prioritizing the pre-disruption strengthening schemes and accelerating the inspection and recovery measures, respectively.

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Retis-Risk is a comprehensive framework recently developed for the assessment and management of the seismic resilience of interurban roadway networks. In this paper, this framework is applied for the road network of the prefecture of Western Macedonia in Greece. Refined data concerning real traffic conditions and network topology were collected and a detailed network mapping was performed in GIS. Utilizing an ad-hoc developed software for implementing the holistic methodology, the as-built road network was assessed and the network components with the highest vulnerability and consequence were identified. To improve the loss assessment reliability, bridge-specific fragility curves were employed based on the refined FE modeling. Structural and traffic cost due to earthquake scenarios of different return period were then predicted. To identify effective loss mitigation measures, the whole process was repeated assuming two different pre-earthquake risk management strategies. The first one concerns a retrofit program tailored to selected (i.e., the most critical) network components, while the second one focuses on the beneficial effect of a better recovery planning. Results indicate the significant contribution of an effective risk management to the loss mitigation and network resilience improvement. Moreover, a sustainable health monitoring system was installed on Polymylos bridge to ensure satellite data transmission during an earthquake event to update the postearthquake recovery model, nearly in real time, with the measured spectral acceleration of the superstructure. The results indicate that the road network is adequately resilient, primarily due to its newly constructed infrastructure and its compliance to modern seismic standards. However, it consists an interesting application case demonstrating the applicability of the methodology and the major potential benefits of a holistic resilience-based management for the case similar intercity highway networks.

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