The City Line is a project to bore a new 6 km rail tunnel under central Stockholm between Tomteboda, northwest of the city, and Stockholm South station. It will enable more traffic to be routed through the narrow approach to the city centre, easing congestion and increasing capacity by providing local commuter trains with their own dedicated section of track through the city. It will also have two central underground stations to relieve city centre rail traffic. This will double capacity through the city from the current 24 trains per hour in each direction to 48.
The Swedish Rail Administration has appointed WSP to project manage the track, water and waste water installations for the entire length of the tunnel. WSP will also undertake rock investigation, geotechnical and construction work for the northern half of the project.
Building a new rail tunnel in a city centre between 10 and 40 m below the surface is a very complex and high-risk undertaking. In fact, the project’s geotechnical models are the most complex ever run in Sweden. The new tunnel intersects the existing subway in two locations, so blasting necessitates the relocation of the subway track. WSP’s activities include the preparation of a new prefabricated bridge concept to carry traffic during the construction period.
The new tunnel has several interchanges with services tunnels carrying traffic control, power supply, water, waste water, telecom and energy lines. Access tunnels will also be required for the removal of building materials and blast rubble.
Project information
Client: The Swedish Rail Administration
Project size: 6 km rail tunnel
Project value: £7400M
Status: City Line opens in 2011