Home to over a fifth of Sweden’s population, the capital Stockholm is the country’s busiest rail centre. Each day, a quarter of a million passengers step into one of Stockholm’s commuter trains (Pendeltåg) to get to work or school. However, the railway tracks south of Stockholm cannot manage the capacity of today’s rail traffic. Thus, there are often delays in Stockholm’s commuting traffic
To solve this capacity problem a new twin-track railway is being constructed together with an approximately 6 km long tunnel that will start from Stockholm South and end in Tomteboda. The new tracks will double the train capacity in the city.
The Stockholm City Line (Citybanan) will be used by commuter train services. Other services will continue to run on the existing two tracks via Stockholm Central. Two new stations will serve new commuters, and a 1.4 km railway bridge is also being built at the same time. The two new stations City and Odenplan, placed beneath the subway stations T-Centalen and Odenplan, are going to replace the commuter train stop at Stockholm central and Karlberg.
Eliminating a traffic bottleneck
All rail routes south of Stockholm Central currently come together on two tracks. These were established in 1871 when the station opened. It now carries 550 trains daily; something that makes it a bottleneck for commuters and other train passengers in the Swedish capital.
Another problem is that the existing double tracks carry all rail traffic southbound. Thus meaning that, any operating problems can have a huge impact on the entire national rail system. Currently, about 80% of the national commuter trains in Sweden use Stockholm as their start/end station.
Ramboll has therefore been involved in the tendering process that will improve the punctuality and the frequency of the future rail traffic in Stockholm.
Ramboll has also helped with design, as well as with the documentation for administration purposes. Furthermore Ramboll is also providing technical support during the construction of the lot between Söder Mälarstrand – Årstabron. The rock tunnel is a 600 m long double-track tunnel, with a parallel service tunnel, and two access tunnels. Technical challenges are e.g. low rock cover, and passages that are crossing close to existing tunnels and buildings.
High air quality
The client, the Swedish Transport Administration (Trafikverket), has also expressed a high ambition for clean air at e.g. platforms, stations and other relevant buildings. The ambition is that the air in The Stockholm City Line should be significantly cleaner than the air in the metro.
Ramboll has thus been commissioned to design the tunnel ventilation, as well as the general and fire ventilation for the planned railway tunnel in Stockholm. Concretely, this means that temperature, air velocity, particle and carbon dioxide levels, and changes in pressure and relative humidity have been taken into consideration in order to ensure the highest air quality possible.