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St Petersburg to build world’s widest bored tunnel

Photo: NCC
Upon completion in 2016, the Orlovski Tunnel's width of 19 metres will make it the world's widest bored tunnel.
A specially designed bore machine will be needed to dig the 19-metre diameter Orlovski Tunnel in St Petersburg, Russia. COWI has been selected as Engineer to examine the tunnel project’s documents and conduct an independent design assessment before construction begins in late 2011.

During the ice-free months of March to November, the city of St Petersburg raises its 22 drawbridges every night so ships have open sailing routes all the way to Moscow.

The raised bridges provide a scenic sight in “the Venice of the North”, but they also present a major traffic nuisance for cars and lorries, which have only limited crossings in Russia’s second largest city.

Open 24/7
The new Orlovski Tunnel is designed to alleviate the congestion. Measuring just over one kilometre long, the bored tunnel will allow traffic to flow freely without disrupting shipping on the Neva River. Some 60,000 vehicles are expected to pass through the tunnel daily when it enters service in 2016.

The tunnel’s owners, Neva Ltd Concession Company and the City of St Petersburg, have selected COWI as Engineer on the project, which has an estimated cost of RUB 44.7 billion (EUR 1.1 billion).

Morten Faurschou, COWI’s project manager on the Orlovski Tunnel, says COWI’s specialists are already in the midst of conducting an engineering review, commenting on geological and hydro-survey findings as well as conducting independent structural calculations and verifying designs for the tunnel’s ventilation system. 

Tight deadline

The project holds a certain amount of prestige for everybody involved, he adds, since the tunnel’s width of 19 metres makes it the world’s widest.

The adjoining on-shore structures, which include huge shafts needed for launch and retrieval of the tunnel boring machine and the 15 to 50-metre deep excavations needed for the cut and cover tunnels, will also be subject to the independent design verification by COWI.

“The Orlovski Tunnel is an enormous investment for Russia as well as the city of St Petersburg,” says Faurschou. “Our job is to come in as an impartial party and ensure the quality of the design.”

According to Faurschou, by the end of March 2011, COWI will have examined the builder’s documentation and conducted an analysis to ensure compliance with the concession agreement. If all goes according to plan, construction will begin by the end of the year.

By Uzi Frank
Published: 10.02.2011

LAST UPDATED: 16.02.2014