More than 60 companies have participated in the preparatory work on the Norwegian Follo Line Project. All the preparatory work will be terminated by summer 2015.
10 contracts have been awarded for the preparatory work. The main contractors have brought along subcontractors to prepare the different areas before the main construction work commences later this year. At Oslo Central Station, the preparatory work is finished. At the Åsland rig area on the outskirts of Oslo, and by Ski public transport interchange, the preparations will continue over the next few months.
This spring and early summer, four EPC-contracts are scheduled to be signed, before the main contractors can go ahead with the construction work.
Getting ready
Oslo Central Station is the largest public transport hub in Norway. More than a thousand trains pass through the station every day. Despite the heavy traffic, the companies have been working regularly and intensively for two years. Relocation of cables will ease the access to areas around the station and prevent disruptions of the daily flow of traffic to and from this busy station. Space for more and better tracks is needed, and some of the buildings nearby have been demolished. A temporary bridge for the Østfold Line has been established, ensuring that trains will not be affected by the construction of the concrete tunnel for the Follo Line and the relocated Østfold Line. Some buildings close to the construction site will be affected by noise and vibrations, and these buildings have been improved with new windows, venting and facade alterations.
The Follo Line will pass under a part of the Oslo Medieval Park, which is considered to be of great archaeological and historical significance. In cooperation with the Norwegian Directorate for Cultural Heritage an extensive excavation programme is in progress. Last summer more than a hundred ancient graves from the Middle Ages, belonging to the graveyard of former St. Nikolas Church, were revealed in this area.
In 2014 the area close to the Medieval Park was prepared for later sheet pile and lime pile stabilization. During this work large quantities of polluted masses were removed. When the Follo Line is finished, the City of Oslo will have the opportunity to establish a park with a green area almost twice the current size.
Preparing the rig area
At Åsland rig area, AF Gruppen AS is preparing the main rig area for the tunnel operations. This will become a huge rig area, and will include facilities for the production of precast concrete segments and temporary storage of excavated materials. It will take more than one year to prepare the large rig area for the EPC TBM contractor.
From Åsland, the 20 kilometre long tunnel will be excavated by four hard rock shielded tunnel boring machines (TBM). The TBM tunnel construction will be accessed and supplied through two access tunnels, being excavated by drill and blast technology. Each access tunnel will be approximately 1000 metres long, and the company is over half way through. The work is on schedule. Over the last few weeks the company has excavated approximately 60 metres a week in each tunnel.
A transformer substation is also being constructed at Åsland. When finished, it will produce up to 40 megawatts, and supply both the four tunnel boring machines and the rig area with power. When the Follo Line is finalised, the substation will probably supply power to a new residential area considered by Oslo Municipality.
Broad activity in the city of Ski
The preparatory work in and around the city of Ski, is on schedule and will be finalised this summer. 600 metres of one of the main roads has been altered, a small stream has been relocated and a new temporary road for construction purposes has been constructed. Close to what is now Ski rail station, a huge building has been partly demolished and rebuilt to provide space for more tracks at the new station. The stabilisation of the ground between the city of Langhus and Ski is nearly finished and in total 520,000 consecutive metres of lime piles have been installed.
The Follo Line will run along an open section of approximately 1500 metres south of the tunnel before reaching the public transport hub at Ski. The new Ski Station will have six tracks, three central platforms and a new pedestrian underpass. In connection to the station a new road bridge, bus terminal and enlarged car park will be built. It will also be necessary to realign the Østfold Line in order to achieve efficient train operations. Accessibility, efficient transport and integration into the urban landscape are important factors to the Norwegian National Rail Administration.
(Source: Jernbaneverket)
