Technical Excursions

Energy and multi-utility tunnel network of Helsinki
Beneath Helsinki lie more than 40 km of Helsinki Energy’s multi-utility and energy tunnels, which contain district heating and cooling pipelines, 110 kV cables, medium-voltage cables and optical data transfer cables, as well as the main pipelines of Helsinki Water.


Temppeliaukio Church
Temppeliaukio Church was built into solid rock in 1969; for this reason it is also known as the Church in the Rock. Natural light brightens the inside through 180 skylights placed between the dome and the wall of the church, which is often used for concerts because of its excellent acoustics.


Itäkeskus underground swimming pool
The underground swimming pool was carved into bedrock in 1993. The spa-type underground space contains a 50-metre swimming pool, whirlpool baths, saunas, a gym, etc. The facility can be converted into a shelter for 3,800 persons.

Viikinmäki underground wastewater treatment plant
Helsinki Water has centralised all of its wastewater treatment operations into the Viikinmäki wastewater treatment plant. The total volume of excavated rock was 1,200,000 m3. The first phase (1,000,000 m3) was excavated in 1988-91 and the second phase (200,000 m3) in 2000-01.

Otaniemi - underground spaces
Over 50 underground spaces, including the national film archives, the underground shelters of the Dipoli conference centre and VTT Technical Research Centre of Finland, Helsinki University of Technology campus area connection tunnels, Laboratory of Rock Engineering test tunnel, etc.

Western metro expansion
13.9-km long twin tunnel and 7 new stations. Construction is estimated to start in late 2009 and the project is expected to last four years at most. The westbound metro line will be owned by the cities of Helsinki and Espoo.

KEHU - Helsinki Service tunnel
2.5-km service tunnel across the city, from east to west, under the historical centre of Helsinki. Construction scheduled for 2006-10. The tunnel will be used to service shops, restaurants, offices and hotels in the area.

Underground coal storage and district cooling
Helsinki Energy’s underground coal storage facility in Salmisaari was built in 2001-03. The project also included an underground district cooling centre, a power station and 3.5 km of tunnels. The total excavated volume was 550,000 m3. Each coal silo is 65 metres high and has a 40-metre diameter with a circular plan cross-section. The volumetric capacity of each silo is 81,000 m3.

Airport transit (Kehärata)
Airport transit is a new rail section connecting the city centre to Vantaankoski local track with the main northbound rail track. The whole project consists of 18 km of new double track and 8 new stations. Of this, 8 km of track and 4 stations will be fully underground. The owners of the project are the Finnish Rail Administration and the City of Vantaa.