Rv. 555 K3 Sotrasambandet

  • Client / Design: Statens vegvesen, Region vest, Nygårdsgaten 112, 5015 Bergen
  • Contractor: Joint venture Metrostav – Bertelsen & Garpestad
  • Contractual time period: 6/2018 – 5/2020
  • Contractual price: 287.442.907 NOK excluding VAT, 30 million EUR (Approx.)

Project Description

This project was a part of the preparation works for the construction of a new connection between Bergen centre and Sotra island. It is to relocate a high voltage line in which trails there will be a new bridge constructed later. That line will be moved to an existing bridge where cable tunnels to protect the line are being built on both ends. The scope of the project was the excavation, support and technical installations of tunnels Breivik-Drotningsvik (1445 m) and Knarrevik-Litlesotra (1750 m), shafts Drotningsvik and Litlesotra, tunnel portals, drainage and pumping system and preparation for connection of the existing line. Metrostav was responsible for the excavation and support of both tunnels, pumping stations and reservoirs.

Project data

Tunnels: 2 pcs (1445 m+1750 m)
Tunnel portals: 2 pcs
Shafts: 2 pcs (12 m+18 m)
Pumping stations: 2 pcs
Reservoirs: 2 pcs
Blasting on surface: 4.000 m3
Mass transport total: 104.000 m3
Tunnel profile: T5,5 (24 m2)
Blasting underground: 100.000 m3
Sprayed concrete: 7.100 m3
Cement grouting: 410.000 kg
Bolts: 12.500 pcs
Reinforcing SC arches: 300 m
Water insulation: 3.000 m2
Large diameter boring: 1.000 m
Cable ladder: 10.100 m

Challenges / Specifics of the project

  • Excavation in small profile under an inhabited area
  • Very limited space for site arrangement
  • Noise limits
  • Vibration limits
  • Excavation in close vicinity to high voltage installations
  • Excavation under the sea with uncertain geological conditions
  • Testing of Amberg TSP for geological prediction ahead of a tunnel face
  • Excavation under an existing bridge in difficult geological conditions
  • Excavation of reservoirs under the level of the main tunnel
  • Vertical breakthrough into a shaft
  • Coordination of processes after the excavation

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