Conducting risk assessment of geohazards and planning for both new and existing roads
Roads, expressways, and other public facilities helped reduce damage and loss of life in the 2011 Great East Japan Earthquake by providing protection against flooding, owing largely to successful risk assessments carried out pre-construction. For example, the East Sendai Expressway (elevation of 7 to 10 meters) acted as a secondary barrier against the incoming tsunami, preventing the waves from penetrating further inland. Over 200 people escaped by running up to the expressway, and its embankment served as an evacuation shelter for local residents.
- Having sufficient resources to conduct risk assessments.
- Availability of relevant data to conduct accurate assessments and inform planning of new and existing roads.
- Pre-concept risk identification is crucial. For new roads, geohazard risk evaluations enable management authorities to make informed decisions on how to avoid hazardous locations.
- Hazard mapping, evaluation of exposure levels, and determining potential impacts on the social environment are essential for holistic road geohazard risk management.
- Determining potential economic impacts incurred from loss of road access and conducting a cost-benefit analysis of potential investments to mitigate geohazards are critical. The results of these assessments help identify and prioritize endangered locations and inform risk reduction measures.