Key results of the Swiss wide natural hazard risk assessment on national roads

Luuk Dorren and Philippe Arnold

Since 2008, the Federal roads office FEDRO is owner and manager of all national roads in Switzerland, which comprise the highways as well as most of the mountain passes of key importance. As a result, Swiss-wide, standardized information on natural hazards that threaten national roads (highways) was not available. The FEDRO therefore decided to initiate a four year project aiming at quantifying and mapping all risks due to natural hazards threatening Swiss national roads. This paper presents the methodology used in this project and presents a summary of the monetarised risks of the evaluated road sections. The natural hazards that are assessed are snow avalanches, rock- and icefall, flooding, debris flows, landslides (permanent, spontaneous and slope type debris flows) and collapse dolines. Risk hot spots mainly occur due to road closure related to rockfall or bank erosion. Damage to infrastructure represents generally only up to 20 % of the total calculated risk; person risks add up to 8 % of the total risk.

2016/1 487-493