Gotthard Base Tunnel Case Study

June 01, 2016

The Gotthard Base Tunnel – the centerpiece of the new Alpine transversals – is scheduled to go into operation.

March 23, 2011

Main breakthrough in the Western tunnel between Sedrun and Faido.

October 15, 2010

Main breakthrough Tunnel in the Eastern tunnel between Sedrun and Faido.


Mechanized tunnelling is successfully completed in the north.


The dreaded Piora Basin is successfully crossed by the S-210.


The Herrenknecht TBMs on the northern and southern sections of the Base Tunnel reach their first target –up to nine months ahead of schedule.


Tunnelling work with the four Herrenknecht Gripper TBMs begins.


The first machine orders are awarded to Herrenknecht.


Excavating activities begin in Sedrun with the first blasting works.


The Swiss government approves financing for the New Alpine Transversal (NEAT).


The first preparatory and exploratory work for the Gotthard Base Tunnel begins in Sedrun.


Exploratory drills begin at the Piora Basin.


The first road tunnel is opened to traffic and connects Göschenen with Airolo.


Construction of the first road tunnel through the Gotthard begins.


The integration of the electrical enclosure climate control units (figure 4: Pfannenberg cooling unit DTGT mounted on the back of the electrical enclosure) into the central tunnel system was a further requirement which had to be implemented.As a result of the integration, there will be the possibility to access all operating data of the cooling unit in the future.

Thus, the current temperature of the electrical enclosure can be read for example, or the hours of operation of the most important main components can be monitored. This is especially important to prevent unplanned failures and downtime and, by planning maintenance works in advance, to guarantee a high level of system uptime.

Pfannenberg’s new Generation of Controllers, designed especially for this project, have an Ethernet transmission protocol, and provide a variety of parameters which can now be monitored in the central tunnel control. These heaters ensure that the temperature inside electrical enclosures does not fall below the so-called dew-point. The dew-point is the temperature that moist air has to drop to – by unchanged pressure – so that the amount of water dissolved in the air is precipitated as condensate. At the dew-point, the relative humidity is 100%; that means that the air is saturated with water vapour.

The controllers are not only used directly inside the cooling units. The climate controller was also integrated into 500 other electrical enclosures without a cooling unit. This makes a temperature monitoring system possible, which, like the climate control units, can communicate with the tunnel control system and, if necessary, can be replaced with such, without having to reinstall the data transfer.

Another first in this development is attention paid to energy efficiency. An intelligent control concept was implemented for this, optimizing the energy efficiency, which is already very good in the active cooling mode, additionally in the passive mode (only the electrical enclosure air is circulated). Due to the integration of a temperature sensor at the allegedly most critical point inside the electrical enclosure, the internal fan responsible for the circulation of the air in the electrical enclosure is only switched on when a defined limit temperature is exceeded. The cooling unit does not start to cool actively again until a limit temperature is exceeded despite the circulation of the air. This control concept helps to reduce the energy consumption further, since all active components are switched off in the event of the energy saving mode described above.

Another important point is that the uptime of the units is guaranteed to last for 10 years after the initial operation of the tunnel in 2016. This results in the increased demands to maintenance friendliness. Thus, the MTTR (Mean Time to Repair) has to be as short as possible, this means the time necessary to replace the components quickly and easily in the framework of defined maintenance work.

In 2010 the first cooling units were delivered to the company Swibox. In the meantime, all units have been delivered and will be installed one by one, together with the electrical enclosures, in the 176 cross passages of the Gotthard Base Tunnel. They have already been able to prove their reliability every day, as the various test phases started a while ago and will continue until the start of the scheduled railway operation on 2016.

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