Expanding this 19.5 km section from two to four tracks is the National Rail Administration’s principal investment project this present decade. With a total cost of approximately 7 billion NOK, it is currently the largest single on-shore infrastructure project in Norway.
The section between Skøyen and Asker on the
With capacity stretched to the limit, if one train is delayed, this easily spreads to other services. As a consequence, punctuality on the
The area to the west of
The expansion between Skøyen and Asker will make it possible to improve and expand rail services on the
Between stations, the new tracks will be built for a speed of 160 kilometres per hour, cutting travel time between Skøyen and Asker from 20 to 13 minutes.
Work on the 9.5 km between Sandvika and Asker (3.7 bn NOK) began in 2001 and was completed in August 2005.
The second phase will see the reconstruction of Lysaker station and a 1.2 km section of line from 2006 to 2009. The 6.7 km section between Lysaker and Sandvika, which includes a 5.5 km rock tunnel, is scheduled for 2007-11.
A full development of the final section, between Skøyen and Lysaker, has a marginal cost benefit and is not included in current long term plans, which cover the period until 2015.
When the Sandvika-Asker section was completed in 2005, the project passed its halfway mark. This has already eased regularity problems considerably, but to reap full benefits in terms of capacity and travel time, the entire section between Lysaker and Asker must be completed.
Among the most notable challenges in all phases of the project is the carrying out of heavy construction work close to the existing track, where trains run as normal. This entails meticulous planning and a wide range of safety measures.
This was particularly the case at Asker, where a full reconstruction of the station area was necessary in order to integrate the new double track with existing infrastructure. The number of tracks was increased from five to six.
In Sandvika, two new viaducts (150 m) carry the quadrupled line over a river in the town centre. There is also a new 100 metre concrete bridge spanning the E16 motorway. In both cases, work has been carried out in several stages, enabling rail traffic to pass during the construction period.
The new fast lines flank the existing local tracks through Sandvika, before diverging into the first tunnel through a cut and cover dive-under junction. The total length of cut and cover tunnels between Sandvika and Asker is almost 1 km.
There are two rock tunnels, with a total length of 6.3 km, separated by a surface section of 600 metres. Both tunnels were blasted and attacked at three fronts. The cross section is approximately 105 m2.
The area around Lysaker is a rapidly growing business district. Lysaker is
The station will be developed to provide easy transfer between rail, bus and other forms of transport. This entails a new bus terminal and taxi rank, a new ‘kiss and ride’ area and improved pedestrian access.
There will be a full reconstruction of the station area, with many of the same challenges encountered at Asker. Work started in 2006 and will be carried out in two stages, with completion in the summer of 2009.
Firstly, two new tracks with platforms were built on the northern side of the old station. This part of the station is now in use and work has started on extending the south side.
Also part of the project is a new 110 metre bridge spanning the Lysaker river in parallel to the existing stone arch bridge from 1913. The development also includes a new 50 metre steel girder road bridge spanning the railway.
Lysaker - Sandvika
This new 6.7 km section branches off from the existing line just west of Lysaker station, where a 150 metre cut and cover dive-under tunnel will be built. A 5.5 km rock tunnel then carries the new double track to Sandvika, where old and new lines converge alongside Lake Engervannet.
The new tunnel will be attacked from both ends, as well as in both directions from two separate crosscuts. Conventional drill and blast technology will be used.
Geology on this section closely resembles that of the Sandvika-Asker tunnels and the National Rail Administration is aiming to build on previous experience from this section to ensure optimal results.
Construction started in spring and summer of 2007 and the section will be opened in 2011. There are four main groundworks contracts which have been won by the firms Skanska AS, NCC Construction AS and Veidekke Entreprenør AS (two contracts).
In all phases of the project, the National Rail Administration works actively to safeguard the environment and minimize negative consequences for the public and surrounding areas. An important tool is a special Environment Programme, which has been developed in close cooperation with local authorities.
The programme stipulates measures and prerequisites for a number of different issues during the construction period and all contractors are contractually obliged to follow the measures which are outlined.
To prevent tunnelling from affecting the ground water table, an extensive and systematic grouting process has been stipulated for the full length of the tunnels. There are strict limits on water leaks, based on thorough research of local geology, environment and neighbouring infrastructure.
The Environment Program also stipulates monitoring programs for a number of other factors, such as pore pressure, possible ground subsidence, vibrations, noise, and so on.