The county road Fv. 53 Tyin – Årdal, is in Oppland county on the border to Sogn & Fjordane in Norway. It’s an important road for the inner parts of the Sogn region and especially the local community in Årdal.  A large part of the road is located above tree line, which makes it very exposed to winter storms and avalanche hazard.

Up to now, temporary closures has been the only way to deal with the extensive avalanche problems along the road, which in several occasions has kept the road closed for several days at the time. The decision of when to open the road again after a closure was often related to a very high degree of uncertainty which lead to increased risk for both maintenance crew and travelers on the road.

Although the avalanche paths threatening the road are not very big (release areas 100 – 300 m. above the road), the large, rather flat area west of the road acts as a very large fetch* and in combination with frequent events of strong westerly winds, the road was exposed significant avalanche danger on regular bases.

 

*Fetch: Area where snow is available for transport by wind.

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Figure 1: Fv. 53 Tyin - Årdal, located on the border between Oppland and Sogn & Fjordane County, Norway.

Construction

In 2016 Wyssen Norge SA got awarded to construct 14 Remote Avalanche Control Systems (RACS) along the Tyin – Årdal road.

The construction started in July and all 14 foundations was completed within 6 weeks. All locations had relatively easy access, so helicopter use could be reduced to a minimum. The towers were erected in two days in September, and the deployment boxes were loaded and placed on the towers in mid November.

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Abbildung 2: Eine fertiggestellte Fundation bereit für die Montage der Sprengmasten oberhalb der Bezirksstrasse Fv. 53
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Figure 3: Placement of a deplyment box on the tower at the beginning oft he winter season by helicopter.

Operational experience

First avalanche control operation in Norway

This is the first time a Norwegian road is protected with an operational avalanche control service using RACS. For the first year of operation, Wyssen Norge was responsible to run the complete operation, including daily avalanche forecast for the road, advising NPRA on when to perform avalanche control missions, execute avalanche control and to document the results.

Increased safety

The avalanche control operation has improved the safety for all users on the road, and maybe most of all, the maintenance crew that has the responsibility to clear the road after closures due to wind drift/bad visibility. Approximatey 100 avalanches have been released preventively in the first winter season (2016/17).

Shorter closures

Due to the possibility to release smaller avalanches from a safe location avalanche control closures have been kept to a minimum while road closures because of wind drift/bad visibility has been reduced because of the change to efficiently control the avalanche hazard before opening the road for traffic.

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Figure 4: Avalanche control 18.03.2017

Thanks to

Wyssen Avalanche Control would like to thanks our partners:

The Norwegian Public Road Administration (NPRA) for an excellent collaboration.

Fjerby AS & DS Entreprentør AS for safe, effective and high quality construction work.

Skred AS for consulting and a good collaboration with the operational program.

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