Monitoring security on Sognefjellsvegen

The Sognefjellsvegen road between Røysheim and Repp in Lom has occasionally been closed. Two years ago, rocks fell and spread over a few dozen metres of the road. Now, road users are being protected by rock protection and a safety fence.

A large and threatening boulder above the exposed stretch of road has been put on continuous monitoring. In mid-November, Cautus Geo established automatic monitoring to ensure the work of rock protection and the establishment of a safety fence that will improve traffic safety for road users.

- It's all about safety. It's not justifiable to have construction work right underneath a large section of rock, or a large boulder if you will, that could become unstable during the work we have to do to create a safer road for everyone who uses it daily," says Henning Paul Garmo, chief engineer at Innlandet County Council.

Autumn and spring

The potentially unstable rock block became very visible during rock clearing in the area earlier this autumn. The work was in preparation for the safety work that started in October. The next phase will come in the spring. Everything will be in place before next summer.

- "It's not safe to work with a potentially unstable block of rock directly above the workplace. That's why we set up monitoring," says Garmo.

Cautus Geo established automatic and continuous monitoring of the potentially unstable mountain section in November. Everything is set up with alerts if movements are detected in the mountain section.

- The monitoring continues as we will be installing the safety fence. That will happen next spring. When the work is completed and the ice and snow have melted, we will stop monitoring," says Garmo.

Partially closed

The Sognefjellsvegen road is particularly important for residents of Bøverdalen. They have no alternative route if the road is closed. This autumn, it has been partially closed since October. Now in December, foundations are being poured for the safety fence. It will be installed next spring. During this work, the road may also be light-controlled or narrowed.

- But the road will not be closed. There may be light regulation or narrowing while the safety work is underway," says Garmo.

- "Movements at the millimetre level will trigger an alarm," says Bjørnar Nevland Knudsen of Cautus Geo. He has led the work of installing the surveillance along the county road.

- "We've done similar set-ups elsewhere, including in Meådalen to secure the landslide area on the Meråker railway," says Knudsen.

Equipment for monitoring on Sognefjellsvegen:

• Total station - measures movements in the mountain section that may be unstable
• Camera - shows and documents any movements in the mountain section
• Cautus Web - real-time analysis of total station data and alarm management and transmission
• Data logger - for e.g. power supply to total station