Finnish geologists: Granite sea floor favors Tallinn-Helsinki tunnel ({{commentsTotal}})

Vertical section of a possible undersea tunnel between Tallinn and Helsinki.
Vertical section of a possible undersea tunnel between Tallinn and Helsinki. Source: (HMV)

A railway tunnel between Tallinn and Helsinki could be built within five years, as test drillings had shown that the ground below the Gulf of Finland along the proposed route of the tunnel was made up of granite.

“That the ground below the sea is made up of granite favors the construction of the tunnel. Technically a tunnel is perfectly possible,” geologist Ossi Ikävalko of Finland’s geological survey center told daily Helsingin Sanomat.

According to an initial plan, at least three tunnels would need to be built, and work on all of them would have to begin in Helsinki as well as Tallinn at the same time. Beyond that, two floating construction platforms half-way down the length of the route on each side would need to be built as well.

As the paper confirms, the Finns have plenty of experience drilling through granite. A Norwegian drilling company estimates moreover that if six drills were to move just ten metres a day, then tunnel construction could progress by a few dozen kilometers every year.

Within the framework of the so-called FinEst Link project, started by the cities of Tallinn and Helsinki as well as the regions of Harjumaa and Uusimaa along with the according ministries of both countries, surveys and studies are currently underway to determine the project’s economic advantages and effects.

Currently three potential routes are discussed, of which the first concerns a tunnel from the city center of Helsinki to Viimsi peninsula northeast of Tallinn. The second would see the tunnel emerge in Tallinn’s Ülemiste district, and the third would take the Estonian entrance to the island of Naissaar, from where the railway would be connected to Tallinn with a bridge.

Editor: Dario Cavegn