THE CHANNEL TUNNEL

This article describes the design and construction of the Channel Tunnel now being built as a rail link between England and France. Two previous attempts to build the Tunnel were made in 1880 and 1975 but soon abandoned. On 12 February 1986, the new project was launched when the British and French governments signed the fixed link treaty. The tunnel is scheduled to be fully operational on 15 May 1993; its estimated cost is 4.7 billion after interest payments and inflation, but the total money raised and available is 6 billion. The tunnel will have three bores: twin rail tunnels of about 8.5 m excavated diameter and a central service tunnel of about 5.7 m excavated diameter. About 156 km of tunnels will be driven to link proposed rail termini at Cheriton, near Folkestone, and Coquelles, near Sangatte, France. When the tunnel is operating, it is expected that the high-speed train journey between the centres of London and Paris will take only three hours. Details are given of the eleven tunnel boring machines and their ancillary equipment, including sophisticated computer-controlled laser guidance systems. All spoil will be transported from the tunnel boring machines to the surface at Shakespeare Cliff and Sangatte; all personnel and tunnel extension materials will also enter the workings there. The construction of the Channel Tunnel presents no new technical problems, although there will be logistical difficulties associated with servicing the multiple advancing faces at both ends. (TRRL)