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Arna Bergen Railway | Renovation of the old Ulriken tunnel

7.7 km
LENGTH
160 km/h
SPEED
3,1 km
VÍA EN BALASTO

Construction of the first Ulriken tunnel, approximately 7.8 km long, began in the mid-1950s and was part of the construction project for the Bergen to Voss railway line in Norway. The construction of the tunnel was a challenge due to the region’s mountainous topography and changing geological conditions. It was inaugurated in 1964. Over time, it became one of the most congested tunnels in Europe.

€41,2 M
Budget
Norway
Location
Construction
Contract type
Bane NOR
Client
2021-2023
Execution period
Azvi

Description of the works

The objective of this contract is to improve the waterproofing of seepages and the rail connection between the existing tunnel and the new tunnel by installing two diagonals.

To carry out the waterproofing, the tunnel section was widened in several sections, bolts were installed and concrete was sprayed.

The waterproofing solution includes a PVC and Foam membrane, with a cavity in the backside to protect against freezing phenomena. The support of the new excavated section of the tunnel includes bolting and shotcreting.

The works were divided into the following areas:

  • Open air area at Fløen and Arna station.
  • Tunnel area from the Arna portals to Fløen, where the tunnel was extended by blasting and the existing railway tracks were removed, facilitating subsequent blasting work.
  • Interior area of the tunnel, where blasting was carried out in 136 separate areas mainly to widen the tunnel and adapt it to the new catenary and ventilation. In this area the railway track was not removed and had to be protected.

This contract also includes the construction of a new railway bridge in the Bergen area, as well as the development of the streets and the construction of a car park for the nearby residential buildings. Sound barriers were installed on the railway bridge.

Inside the old tunnel, the renovation operations included blasting with explosives for the transverse and diagonal galleries.

Relevant Figures

  • Excavation by blasting 41,055 m3.
  • Tunnel frost protection membrane 24,105 m2.
  • Polyethylene foam for tunnel insulation 16,520 m2.
  • Shotcrete vault 24,105 m2.
  • Management of ballast waste 13,385 t.
  • Drainage along tunnel Ø180 PE100 SDR 116.4 km.
  • Formation of the esplanade 11,000 m2.
  • Demolition of bridges 1.
  • Steel for reinforcement 184 t.
  • Construction of a 76 m railway bridge.
  • Concrete structures 1,064.489 m3.

Azvi
Azvi

Main Challenges

The main challenge was to excavate approximately 50,000 m3 of rock by blasting in a single-track tunnel without causing accidents to workers, nearby houses or rail traffic in the parallel tunnel.

Another major challenge was equipment logistics due to the limited space in a small tunnel section, where several activities were carried out simultaneously.

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