UN office for disaster risk reduction defines that structural measures are any physical construction to reduce or avoid possible impacts of hazards, or the application of engineering techniques or technology to achieve hazard resistance and resilience in structures or systems 1.
Structural mitigation measures for roads also consist of measures for structure and measures for systems.
Linkov et al. discuss infrastructure resilience in terms of the resilience of individual infrastructures and the resilience of networks. Not only does it mean that individual infrastructures are low impact and able to recover quickly from a disaster event, but it also recommends efficient and redundant networks in terms of disaster resilience of the supply chain. Infrastructure and network resilience are also important components of structural mitigation measures 2.
As described above, it is important to ensure the disaster-resistant performance of tunnels, bridges, and embankments on longitudinal roads, transverse roads, and urban roads in a unified manner to cope with severe and widespread disasters, so that the roads can function quickly at the time of a disaster. In addition, it is important that multiple road networks ensure uninterrupted human and logistical flow to the disaster area, minimizing the loss of life and economic losses. Figure 2.2-1 shows the schematic image of the measures for structure and measures for systems.
The UK Critical Infrastructure Resilience Improvement Guide defines resilience as the ability of assets, networks, and systems to prevent and mitigate disruptive events, adapt to disruptive events and recover quickly from disruptive events. This also indicates that the four components of resilience components “resistance", "reliability", "redundancy" and ”response & recovery” as shown in Figure 2.2-2 are necessary in order to build infrastructure resilience. Ensuring "resistance", "reliability" and "redundancy" are also the key components of structural mitigation measures3.