Fixed equipment

The fixed equipment installed after completion of the tunnels had to fulfill the following functions:

1) Electricity supply for trains and auxiliary equipment

The power required for the trains and auxiliary equipment is supplied by two principal power stations at each terminal and linked to the national 400 kV networks (Seaboard at Sellindge in Kent and Electricite de France at Les Mandarins in the Nord-Pas-de-Calais) Each network supplies half the requirement but each is capable of supplying all the power necessary for the whole system.

2) Electricity supply for catenaries

The catenaries supply the traction power necessary for the shuttle trains and the through trains. The overhead power lines supply 25 kV - one of the most powerful 25kV catenary systems in existence.

3) Control and communications systems

All the control and communications systems are carried in three fibre-optic cables. These high capacity cables transmit digitally all the data for rail traffic management and all the electrical and mechanical plant in the tunnels. Speech communications are also transmitted by cable but, in addition, there are independent radio systems including:

• concession radio
• track-to train radio
• shuttle internal radio

4) Tunnel ventilation

All trains using the tunnels have electric traction so there is no engine exhaust pollution. The service tunnel vehicles have diesel engines designed to give very low emissions. Air is pumped into the service tunnel from ventilation buildings at Shakespeare Cliff and Sangatte. The service tunnel acts as the supply duct for normal ventilation. Air handling units located above the doors of the cross-passages every 375 meters control the flow of air from the service tunnel to the railway tunnels.

5) Drainage systems

The drainage system of five pumping stations permits the removal of water from the tunnels. Water from normal seepage is directed via channels into storage tanks or sumps at the lowest points and discharged by pipeline to the pumping stations.

6) Fire-fighting

Smoke detectors are installed in all the technical rooms located within the cross-passages. Automatic extinguishing devices and remote control cut-off systems are also installed. A dedicated water supply line in the service tunnel is fed from storage tanks and pumping stations at the portals. This line feeds the fire hydrants in the cross passages and in the running tunnels.

7) Tunnel cooling systems

The temperature in the tunnels is maintained at an acceptable level of 25°C by the circulation of refrigerated water in each section of tunnel via a discharge and a return pipe. Refrigeration plants at the former construction sites of Shakespeare Cliff and Sangatte provide the chilling and circulation systems.

8) Service tunnel equipment

On each side of the service tunnel, technical rooms contain all the necessary electrical and technical rooms for the equipment requirements in the service tunnel.