Severomuysky Tunnel
Encyclopedia
Severomuysky Tunnel is a railroad tunnel
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 on the Baikal Amur Mainline (BAM), in northwestern Buryatia, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. It is named after the Severomuysky Range it cuts through.

The tunnel is 15343 metres (50,338 ft) long, the longest in Russia (excluding metro
Rapid transit
A rapid transit, underground, subway, elevated railway, metro or metropolitan railway system is an electric passenger railway in an urban area with a high capacity and frequency, and grade separation from other traffic. Rapid transit systems are typically located either in underground tunnels or on...

 lines, see List of tunnels by length for comparisons). The tunnel was put into operation on December 5, 2003 (signed off on November 30), with yet another announcement of the completion of the BAM project.

Work started in 1978. The tunnel was built through very difficult rock with four major faults and a great deal of underground water, some at 35 atmospheres (3.5 MPa) pressure. One method used was to pump liquid nitrogen into the rock, freezing the water until the cut could be sealed. In September 1979 workers broke into a fault connected to a 12,000 cubic meter underground lake. This required building a drainage tunnel and delayed work for eighteen months. When it became clear that the tunnel would not be completed in time, a 28 km bypass was built (completed in 1987). This had a 4% grade and traffic was limited to 15 km/h. Passenger traffic was prohibited. A second bypass of 54 km was completed in 1989 which was safe for passenger trains. The tunnel was first used in 2003.
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