Installation of technical infrastructure systems
Following completion of the shell structure, and before installation of the railway systems, the base tunnels are now being equipped with mechanical and electromechanical systems. The technical infrastructure systems comprise ventilation, water supply and drainage systems, ventilation and air-conditioning systems for auxiliary structures and buildings, cranes, doors, technical floors and metal structures, as well as electrical and fire-protection installations. Most of the systems will be installed in the cross passages and the two multifunction stations of the Gotthard Base Tunnel, some also in the tubes and portal areas of the tunnel.
Installations in the cross passages
Through installation of the respective technical systems, the 176 cross galleries in the Gotthard Base Tunnel and the 46 cross galleries of the Ceneri Base Tunnel take on various different functions: they form protected rooms to accommodate cabinets containing railway infrastructure systems. So that the temperature does not rise above 35 °C and thereby impair the high availability and long life of the systems, the cross passages are equipped with a ventilation system. In the event of an incident, the cross passages serve as evacuation routes into the unaffected tube. For this reason, they are closed off with evacuation and fire-protection doors.
Technical systems in the multifunction stations and auxiliary buildings
In both multifunction stations, trains can cross over from one tube into the other. These tunnel crossovers are equipped with special doors which under operating conditions are normally closed. Numerous technical rooms in auxiliary buildings, such as the railway infrastructure systems rooms, must be air conditioned. For this reason, they are equipped with building control systems for cooling and ventilation. Under operating conditions, Shaft I at Sedrun serves not only as a fresh-air duct to the Gotthard Base Tunnel. It also houses various cables for the railway systems and a water pipeline for the multifunction station.
Emergency stop stations for incidents
In each of the multifunction stations of the Gotthard Base Tunnel at Faido and Sedrun are two emergency-stop stations for use in case of incidents. The doors of these emergency-stop stations have a dual function: they can be opened and closed to regulate the fresh-air flow and also serve as escape doors.
Fresh air for the base tunnels
The operational ventilation prevents an unfavourable climate in the tunnel system and provides the necessary air conditions for personnel involved in maintenance work. In the event of a fire in the tunnel, it can suck fumes out and blow fresh air in.
An optimal operating climate in the tunnel is important for the high availability and long life of the technical systems. In summer, the temperature will be around 36-37 °C, in winter, around 35 °C. The tunnel temperature is determined, among other things, by the rock temperature, the temperature of the train when it enters the tunnel, the heat emitted by the technical installations, and the ground water temperature. In the tunnel entrance areas, the relative humidity of the air can be over 70%. With increasing air temperature in the direction of travel, the relative humidity decreases until at the exit portal it is only between 20 and 40%.
Removal of ground water and soiled water
In the Gotthard Base Tunnel, ground water and tunnel water flow out of the tunnel in special pipes. Before it flows out, the tunnel water is examined, processed to the extent necessary, and returned to the natural environment.
In the event of soiled water collecting in the area of the trackbed, at 100-metre intervals it is collected in a shaft and drained into a separate pipeline. The soiled water runs into a collection basin outside the tunnel, where it is analysed.
In the Ceneri Base Tunnel, the ground water and soiled water are not drained separately. The much smaller volume of ground water allows a mixed drainage system.