4692 x 3828 px | 39,7 x 32,4 cm | 15,6 x 12,8 inches | 300dpi
Date de la prise de vue:
24 octobre 1988
Lieu:
Cheriton, Kent, UK.
Informations supplémentaires:
Cette image peut avoir des imperfections car il s’agit d’une image historique ou de reportage.
Cut and cover tunnelling methods at low depth have been used worldwide for centuries and, in locations with no important constraints on the surface, cut and cover tunnels are inexpensive compared to other tunnelling techniques. Cut and cover tunnel construction involves excavating a trench from the surface, building the concrete tunnel in it, and then backfilling and restoring the ground. The cut and cover section of the Channel Tunnel at Holywell Combe was situated in an area of arable land surrounded on three sides by a scarp designated a Site of Special Scientific Interest. 500m2 of chalk grassland was removed (and replaced on completion) to a depth of 150m. 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. The Channel Tunnel consists of three parallel tunnels. There are two rail tunnels carrying trains to and from the UK to France and a smaller access tunnel served by narrow rubber-tyred vehicles and connected by transverse passages to the main tunnels at regular intervals. It allows maintenance workers access to the tunnels and provides a safe route for escape during emergencies.
