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Financial consortium consider the feasibility of the world’s longest undersea tunnel.

Posted by Emily O'Dowd on Mar 19, 2017

80km of sea separates FinlanArtist's impression of the undersea tunnel. (Photo courtesy of Sweco)d’s capital Helsinki with Tallinn, Estonia. This busy water route transports eight million passengers and 7.5 million ferry trips per year. But since 2004, the two city’s mayors have been pushing for an undersea rail route to connect the the Gulf which is used for both commerce and leisure. It is hoped to provide a rapid transport link between Scandinavia and Central Europe. At 92km it would become the largest undersea tunnel and expected to cost between €9-13 billion. Should the project go ahead, a Tallinn-Helsinki tunnel could be a reality by 2030. Last month, a consortium of Ramboll Finland, Sito, Strafica, Urban Research and Pöyry Finland was selected to determine the financial viability and impact of the tunnel project. The feasibility report is scheduled to be completed in the second half of 2017. 

At the moment, the journey across the Gulf of Finland takes around two hours but the undersea tunnel is expected to reduce this to just 30 minutes. Additionally, the project has been considered economically viable as a 30 percent increase in the current passenger and freight traffic would cover more than half of the project investment. It is predicted to treble travel and boost trade between the cities in its first decade and see 25 million journeys by 2040. While the proposed tunnel will include 1,435mm tracks, its design has not yet been finalised.

Hannes Virkus, an adviser at the Estonian ministry of economic affairs, said: “The idea is really good and interesting and worth studying. But if we get the money, it’s going to take at least two years for the analysis to be completed, so only some time in 2018 can we can expect some real decisions on whether the tunnel will be built. It’s still some way away.”

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The consortium will now estimate passenger and freight volumes and undertake a cost-benefit study. This will inform a future decision about whether there is a case for a tunnel, or whether they should focus on developing the current maritime services and improving transport connections to the ports of Helsinki and Tallinn.

There were 10 expressions of interest in the contracts. ‘We received high-quality offers from large planning groups that have international expertise in carrying out large transport projects and assessing their impacts and, moreover, have local expertise in both countries’, said Kari Ruohonen, FinEst Link Project Manager at Helsinki-Uusimaa Regional Council last month.

The FinEst link project is led by Helsinki-Uusimaa Regional Council in co-operation with Helsinki City Council, Finish transport agency Liikennevirasto, the city of Tallinn, the Estonian Ministry of Economic Affairs and Harju County Council. The studies are being supported by the EU’s Interreg Central Baltic programme, with a budget of €1·3 million over two years.

Sweco Projekt and partners conducted the pre-feasibility study for the project in 2015. A joint venture between Sweco, Amberg Engineering and WSP was awarded a contract to conduct technical and economic feasibility studies for the project in February 2017.

The undersea tunnel is made particularly attractive because of a planned €3.6bn Rail Baltica high-speed train line, which will run from Tallinn to Poland and link into western Europe’s rail networks – and could also potentially connect Helsinki directly via train to Berlin and beyond.

The Seikan Tunnel in Japan is currently the longest and deepest underwater tunnel in the world covering a 23.3km distance. Built 140m below the seabed it passes beneath the Tsugaru Strait and connects the Aomori Prefecture on Honshu Island and the Hokkaido Island. Construction began in September 1971 and the tunnel cross section is designed to facilitate Shinkansen trains.

But the title of the longest and deepest tunnel in the world goes to the Gotthard base tunnel which runs for 57km under the Swiss Alps, which officially opened in 2016. It connects Erstfeld in the central Swiss canton of Uri, to Bodio in the southern Ticino canton. The number of daily rail passengers is expected to increase from 9,000 people to 15,000 by 2020, according to the Swiss federal railway service. Construction took 17 years at a cost of more than 12 billion Swiss francs (£8.4billion). The Swiss rail service said it took 43,800 hours of non-stop work by 125 labourers rotating in three shifts to lay the tunnel’s slab track.

For more stories like this you might be interested in:

Undersea Helsinki-Tallinn tunnel megaproject progresses as study commissioned.

The longest and deepest rail tunnel in the world opens for business.

€46 million awarded to Alstom for upgrades to China’s longest metro line in Shanghai.

Europe’s longest driverless metro line goes operational in Barcelona.


Topics: projects

Emily O'Dowd

Written by Emily O'Dowd

On graduating with a degree in English Literature at Royal Holloway University of London, Emily joined the editorial team. When she isn't writing articles for the website or interviewing experts in the industry she enjoys reading, running and sailing.

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