Knowledge Note

Geohazards are the most common type of natural hazards faced globally. Geohazards aff ecting road infrastructure are the geological and environmental conditions, and include most hazards, such as slope slides and collapse, earth/debris fl ows, fl ooding, and erosion. Most related disasters are triggered by phenomena, such as earthquakes or heavy rains. Human factors can also impact the severity of geohazards on roads. This is often due to unsuitable highway planning, a lack of geological surveys, and inappropriate gradients of engineered slopes, among factors .The lack or absence of road geohazard risk management is becoming an important issue not only for road network management but also for socio-economic development. Where there may be some system, there is often an emphasis on emergency response rather than proactive measures. Japan is geohazard-prone and is at risk from typhoons, heavy rainfall, earthquakes, tsunami, and other hazard events. Led by the Ministry of Land, Infrastructure, Transport, and Tourism (MLIT), the country has learned from dealing with frequent road geohazard events to make systematic improvements in its road geohazard risk management procedures.