Main works initiated by the Norwegian Minister of Transport and Communications

The Norwegian Minister of Transport and Communication Ketil Solvik-Olsen has initiated the start of the main tunnel works for the Follo Line Project towards Oslo. This is the first time the tunnel construction method drill & split is used in Norway.

The ceremony took place at the Follo Line Project’s construction site at Sydhavna in Oslo, where the construction of a new tunnel for the inbound Østfold line now has started. 

The drill & blast (including drill & split) contract is one of five EPC contracts for the Follo Line Railway between Oslo Central Station and the new transport hub at Ski. The Italian construction company Società per Condotte d´ Acqua S.p.A (Condotte) executes the works on this EPC drill & blast contract.

Sensitive urban location

The construction area is located in the Ekeberg Hill, close to Oslo Central Station. A cavern is to be built combining the inbound Østfold line and the new double track line The Follo Line. The Follo Line will be crossing existing tunnels and infrastructure, including the crossing of Ekeberg Oil Depot. Due to the sensitive urban location, some of the works will be conducted by using the drill & split method (tunnel construction without blasting).

- Drill & split is chosen for the Follo Line due to the alignment of fragile surrounding infrastructure and existing tunnels. Condotte has extensive experience directly relevant for this challenging scope of the Follo Line Project, underlines Project Director Mr. Erik Smith.

The contract with Condotte was signed in February this year. The planning, engineering and designing process commenced immediately after the signing of the contract, along with various other preparatory activities. Condotte established their construction site in May, and in August the first tunnel activities started. After the initial phase using drill & split, drill and blast will be the main excavation method.

The EPC Drill & Blast contract is scheduled to be finished by early 2018.

The start of the tunneling works for the Follo Line Project towards Oslo was celebrated with the Norwegian Minister of Transport and Communications Ketil Solvik-Olsen present. Here with Elca Romano, one of the specialists from entrepreneurCondotte. Photo: NTB Håkon Mosvold Larsen

This is drill & split  

  • Drill & split is a method for tunnel construction without using explosives (such as drill & blast)
  • To excavate in hard rock with this method, it is necessary to drill a large numbers of holes following a precise geometrical pattern
  • Splitting of the rock is done by an hydraulic cylinder pressing a wedge into the drill whole and thereby breaking the rock into smaller pieces
  • The method implies very low vibration and gives good control during rock outlet
  • This is the first time drill & split is used in Norway.

The Follo Line Project, starting from Norway´s capital, is executed by the Norwegian National Rail Administration on behalf of the Norwegian Ministry of Transport and Communications. 

The Follo Line Project is currently Norway´s largest transport project. The project includes a 22 kilometer long new double track line between Oslo Central Station and the public transport hub at Ski, a 20 kilometer railway tunnel (twin bore), extensive works at Oslo Central Station, construction of a new station at Ski and necessary realignment of the existing inbound Østfold line. The Follo Line is scheduled for completion in the end of 2021, and forms the core part of the InterCity development southwards from Oslo.