Item: AVALANCHE OPERATION FOR ROAD PROTECTION IN GRøTFJORD, TROMSø
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Title: AVALANCHE OPERATION FOR ROAD PROTECTION IN GRøTFJORD, TROMSø
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Mrs. Kaja Krogh [ Troms County Council, Tromsø, Norway ]
- Mrs. Mariia Pihlainen [ Troms County Council, Tromsø, Norway ]
- Ph.D. Martin Stefan [ Wyssen Norge AS, Sogndal, Norway ]
- Mr. Nils Arne Kavli Walberg [ Skred AS, Oslo, Norway ]
Date: 2024-09-23
Abstract: The Troms County Council (TCC) oversees a 2915 km road network, which includes measures to mitigate avalanches on exposed routes. Approximately 100 locations across the county are mapped where avalanches frequently impact roads. One of these locations is along County Road 7768 adjacent to the fjord Grøtfjord, where avalanches historically hit the road 1-2 times every year. Statistically, 78 % of these avalanches occurred when the road was open to traffic. The road is the only access route to Tromvik, a village with 144 inhabitants. The road is threatened by several avalanche paths on the east face of Nonstinden, rising 700 m above the road. Following the county’s cost-effective strategy for avalanche mitigation, 10 RACS towers, a PTZ and thermal camera, and a Doppler radar were installed, all operational since the winter season 2022/2023. These instruments, alongside daily avalanche forecasts, constitute the avalanche operation in Grøtfjord which is one of its kind for avalanche mitigation in Norway. The avalanche forecast follows a structured workflow, resulting in assessments categorized as low, medium, or high mitigation levels. Medium and high levels prompt potential avalanche control missions and road closures, respectively. The radar and cameras have been essential for studying snow cover, avalanche activity, and snow drift. Video footage of each avalanche provides experience and knowledge into avalanche paths and triggering conditions. During the polar night, these tools are crucial for registering avalanches and verifying control mission results. The Arctic Ocean’s proximity brings polar lows, causing unpredictable heavy snow showers and strong winds, which are difficult to forecast. To meet this challenge, a dynamic approach is taken. When needed, forecasts can be issued both in the morning and in the afternoon, and occasionally control missions must be undertaken on short notice. The two most important goals for the operation have been: no naturally released avalanches on open road and to ensure consistent road access, minimizing closures to only during control missions. Following two seasons of operation, no avalanches have hit the road while open.
Object ID: ISSW2024_O7.5.pdf
Language of Article: English
Presenter(s): Kaja Krogh
Keywords: Avalanche operation, RACS, Avalanche detection, Doppler radar, Avalanche forecasting
Page Number(s): 828 - 832
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