Comprehensive monitoring on the Gardermoen Line

NCC is building a new double track from Venjar to Minnesund and has engaged Cautus Geo to carry out extensive instrumentation along the nine-kilometre stretch. This part of the new Gardermoen railway is part of the intercity triangle in Eastern Norway. Double tracks will initially be built to Hamar and then to Lillehammer.

The section from Venjar to north of Eidsvoll is nine kilometres long. A new double track, a 380-metre-long tunnel, several smaller railway bridges and culverts will be built on four of these.

The section will be taken into use in autumn 2022. Construction work will be completed by summer 2023. The contract is priced at NOK 1.6 billion.

Demanding ground conditions

On parts of the route, the ground conditions are demanding and the new double track will be built close to the existing railway. All trains will run as normal throughout the construction period. In addition, there are many historic buildings next to the new double track. For example, it will be close to Eidsvoll vicarage and Wergelandslunden.

- "Cautus Geo contributes to increased safety for everyone working on the site. They safeguard today's traffic on the railway and the many historic buildings located close to the new double track we're building," says Assistant Project Manager Marcus Olsson at NCC.

- Together with NCC, we're also building the Vormtråkk hiking trail. "We're linking it up with the Mjøstråkk cycle path. This will provide a continuous cycle path all the way to Lillehammer," says Cecilie Berglund Gjørtz, Communications Manager at Bane NOR.

Absolutely crucial

- "The work Cautus Geo does is absolutely crucial. "We need to have control of everything that can move in the ground. The monitoring cannot be done manually. The job is too extensive for that," says Olsson at NCC.

Cautus Geo has established automatic measurement with real-time notification. Data from the measurements is collected in Cautus Web. If set limit values are deviated from, the alarm goes off automatically with notification by e-mail and SMS.

- This gives us confidence that the construction is safe, that the ground conditions are under control and that surrounding buildings and facilities will not be damaged," says Olsson.

Comprehensive instrumentation

Cautus Geo has established extensive instrumentation. The assignment involves monitoring the train track, which operates as normal, the Wergeland tunnel, Eidsvoll vicarage and Wergelandslunden, as well as landfill sites where the aim is to verify drainage and stability.

It is NCC that has engaged Cautus Geo.

- "We're instrumenting continuously as the project progresses. This means that we haven't yet finished all the instrumentation, even though most of it is in place," says Sigmund Brekke Langelid of Cautus Geo.

The construction work is on schedule. As of today, it is likely that everything will be completed in line with the framework for the assignment.

Technical facts about the mission

Wergeland tunnels 

• 8 inclinometers in sheet piling (SAAV 3D deformation cables) with a length of 38-42 metres, mounted vertically on the floating point and down to 15 metres below the sheet pile in loose soil. Provides a 3D view of the sheet piling line during excavation and tensioning of struts.
• 12 pore pressure gauges in the sheet pile pit (Geosense drive-in) at depths of 20-30 metres below the top of the sheet pile. Registers possible changes in pore pressure during excavation and measures in the construction pit.
• 14 load cells mounted on horizontal struts in construction pits (Geosense VWLC5050) with capacities up to 10,000 kN (1,000 tonnes). Measures loads on horizontal struts during excavation and subsequent backfilling of the construction pit.
• 6 temperature gauges behind the sheet piling. Monitors temperature in order to implement preventive measures to prevent frost in the structure.

Eidsvoll vicarage and Wergelandslunden

• 4 slope inclinometers (SAAV 3D deformation cables) of 35-55 metres installed in vertical boreholes in loose soil. Monitors stability especially during jet pile actions.
• 9 pore pressure gauges at three different locations (Geosense drive-in) installed in loose masses at depths of 10-30 metres below ground. Monitors changes in pore pressure.

Mass landfills

• 15 pore pressure gauges in five different landfill sites (Geosense drive-in) installed at different levels. Monitors changes in pore pressure as a result of filling the landfills, and verifies that drainage and stability are maintained during the work.

Securing train traffic

• 2 horizontal inclinometers at 70 and 50 metres on the track and wall at the same time as jet peeling near the rail.
• Continuous daily measurement of settlement and deformation on tracks in summer and autumn 2019.
• Automatic notification by email and SMS