TUNNEL COOLING, DRAINAGE AND FIRE FIGHTING

This paper describes the three main pipework systems in the Channel Tunnel. These systems have more than 350km of main pipes, and provide for cooling, drainage, and fire-fighting services. Each system operates automatically, and can be controlled remotely, as required. As far as possible, the drainage and fire-fighting systems are both based in the service tunnel or at locations easily accessed from it. This permits maximum maintenance access, without disruption of train services. Both these systems have built-in redundancy to provide high reliability. The cooling system is unusual for a tunnel. In the case of the Channel Tunnel, it is required because of the unprecedented levels of power, needed to overcome shuttle aerodynamic resistance to movement within the tunnel, and the high forecast traffic levels. A new form of cooling system was developed, which circulates chilled water in the running tunnels, and provides heat exchange across a continuous bare pipe surface for friction energy and other losses, rejected as waste heat to the tunnel air. The cooling pipes need almost no maintenance. For the covering abstract see IRRD 877203.