ABSTRACT

The City Rail Loop is a significant railway development project planned below the Helsinki city centre, Southern Finland. The loop-shaped two-tunnel track railway line runs from Pasila and back via underground stations at Töölö, Helsinki city centre, Hakaniemi. The total length of the railway line is 8 km of which 6 km is underground. The service and rescue tunnel runs alongside the track tunnels. Planning of the railway is still in progress. A large design challenge of the Töölö section comes from the necessity to bypass the large amount of existing tunnels in the area. A 70 m part of the track is designed with a very thin rock cover. Other parts with a total of about 100 m are designed as concrete tunnels using cut-and-cover excavation, including 70 m in the proximity of the Olympic Stadium. Complex geometry of the Töölö station adds to the challenge. The project is co-financed by the European Union, Trans-European Network (TEN-T) and Connecting Europe Facility.

INTRODUCTION

The City Rail Loop is a significant railway development project planned below the Helsinki city centre in Southern Finland. The public transport system must be able to accommodate a continuously growing number of passengers. At present there are nearly 1.4 million inhabitants in the Helsinki region. This number is expected to increase by 40,000 this decade and by more than 400,000 during the next few decades. The City Rail Loop will enable efficient railway traffic in a large area. As a result of the new railway section, rail capacity can be freed up on the now too congested stretch between Helsinki and Pasila, allowing trains to run at more frequent intervals. The loop-shaped two-tunnel track railway line runs from Pasila and back via underground stations at Töölö, Helsinki city centre and Hakaniemi. The total length of the railway line is 8 km of which 6 km is underground. The service and rescue tunnel runs alongside the track tunnels. This paper concentrates on the design challenges at the Töölö section of the project (Figure 1).

The detail design phase of The City Rail Loop was finished during spring of 2017. The reservation of The City Rail Loop in the city plan is valid for 5 years. It may possible to obtain a construction decision during this period but it is also possible that other projects will be politically prioritized ahead the City Rail Loop.

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