Operational safety for the longest railway tunnel in the world.

Development of a thermal management concept for electrical enclosures in the 57 km long Gotthard base tunnel (Switzerland). Maximum route capacity: over 300 goods and passenger trains per day at speeds of 160 km/h to 250 km/h, at three-minute intervals during the day.

Application requirement.

Compliance with the IP 65 protection system even under extreme air pressure fluctuations caused by passing trains. Tolerance to extreme temperature differences and resistance to dust and humidity. Ensuring maximum availability during continuous use.

The Pfannenberg solution.

Working in close cooperation with the client and the electrical enclosure manufacturer, we developed a new series of cooling units: the DTGT 9041 and DTGT 9541 models designed specifically for use in tunnels.

The cooling units have:

  • A specially developed pressure element with integrated electric circuit.
  • A new generation of controllers with Ethernet protocol for central function monitoring.
  • An intelligent control configuration to maximize energy-efficiency.
  • A guaranteed operating period of 10 years with defined maintenance measures for short MTTR*.

*MTTR: Mean Time To Repair


Approximately 980 DTGT 9041 and DTGT 9541 cooling units were installed in the region of 176 cross-cuts along the course of the tunnel. The cooling units work perfectly with air pressure fluctuations of up to ±10 kPa, temperature differences of –20 °C to +40 °C and humidity levels of up to 100 %. A central control unit monitors the current temperature in the electrical enclosures and the operating time of the most important components. This allows planning maintenance work in advance in order to eliminate system failures and to ensure a high level of system availability.