The Year of Geology 2016

The Tallinn tunnel will be chiselled into the bedrock

During late 2017, we will finally get a summary of result on whether it is financially profitable and technically possible to build an undersea railway tunnel between Helsinki and Tallinn. The study has been commissioned by the cities of Helsinki and Tallinn, the regions of Uusimaa and Harju, and the Ministry of Economic Affairs and Communications of Estonia and the Finnish Transport Agency.

GTK carried out soundings on the tunnels route alternatives on the Gulf of Finland upon the assignment of the Helsinki–Uusimaa Regional Council. The soundings resulted in a detailed image of the geological structure of the seabed and deposits on the entire route. The survey revealed that solid bedrock continues from Finland all the way to the coast of Estonia.

According to Olli Keinänen, chief adviser of the Regional Council, the investigation has proceeded as planned and expectations are high. It is expected that the final report will be of high quality.

“We want to raise discussion during the project. That is why we keep publishing these results as soon as we get them,” Keinänen says.

The project is also open to ideas from other sources.

“We challenge technology companies to innovate modern solutions for a conventional railway tunnel. The international challenge runs until the beginning of 2018,” Olli Keinänen says.

Going all in

The sounding of the seabed carried out by GTK was the first accurate geological survey conducted between Helsinki and Tallinn. The survey methods included acoustic-seismic sounding, which was used to measure signals reflected from the bedrock. This geophysical method was utilised on the Geomari research vessel, which is owned by GTK and the Naval Research Centre.

After seabed sounding, a consortium of five consulting companies will produce information on whether designing the tunnel is justified or would it be better to continue developing the ferry traffic. Passenger and freight traffic volume evaluations will be made for both, and commuter traffic will be evaluated separately.

Three consulting companies will study the technical and financial requirements for constructing the tunnel.

An outline of the tunnel’s route and the locations of the stations and depots will also be sketched. In addition, it will be studied, what would be the best way to connect the traffic in the tunnel with the mass transportation and railway networks of the cities.

After the investigation is complete, it will be decided for good, whether the undersea tunnel between Helsinki and Tallinn will be constructed.