Engineers install piston relief duct in Channel Tunnel rail tunnel allowing excess air pressure to escape into other rail tunnel
When a train passes along a close-fitting tunnel, air pressure builds up in front of the train that eventually affects economy and passenger comfort. In a land-based tunnel, this air is usually allowed to escape to the surface through special air ducts but, under the sea, this isn't possible. The Eurotunnel system ingeniously allows this air pressure build-up to escape into the opposite rail tunnel through a series of 2m diameter piston relief ducts situated every 250m and looping over the service tunnel. The Channel Tunnel is no ordinary project. The four types of cross-channel service that the Tunnel offers - conventional freight and passenger trains, plus two types of road vehicle shuttle have made it into the busiest railway in the world. The fast and efficient movement of road and rail traffic into, through and out of the Eurotunnel system is integral to that success. The Channel Tunnel is one of the wonders of the modern world. It is thirty-two miles long at an average depth of 45 metres below the sea-bed, the longest undersea tunnel and the second longest rail tunnel in the world (only the Seikan Tunnel in Japan is longer). It was built between 1987 and 1994 by Anglo-French consortium TransManche Link and is owned and operated by Anglo-French Eurotunnel plc. It opened for business in late 1994, offering services including a shuttle train for car, coach and freight vehicles, a Eurostar high-speed passenger service linking London with Paris and Brussels and a rail freight service. The tunnel boring machines were specially designed for excavating the chalk marl rock which lies beneath the seabed along the tunnel route. Digging the tunnel took 15 thousand workers around 170 million man-hours over 7 years with tunnelling happening simultaneously from both ends.
Size: 3048px × 2930px
Location: 40m under seabed between UK and France, Europe
Photo credit: © qaphotos.com / Alamy / Afripics
License: Licensed
Model Released: No
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