The largest heavy load so far rolls through the Gotthard tunnel

A transport of superlatives rolled through the Gotthard railway tunnel this morning. A 120 metre long train transported a transformer weighing 180 tons from Erstfeld in the Swiss canton of Uri to an Alpiq substation in Lavorgo in the Swiss canton of Ticino. This is the largest heavy load that has ever passed through the tunnel. The refurbishment of the Lavorgo substation is an important investment into the security of energy supplies in Switzerland.

180 ton transformer arrives at the Alpiq substation in Lavorgo

In the Alpiq substation in Lavorgo the old transformers are being replaced by new ones this year. The last of the four transformers, each weighing 186 tons, reached its destination on the morning of 14 March 2011. With this the last stage of the transport from the Siemens factory in Weiz, Austria has been successfully accomplished. It was without doubt the most challenging stage, for about the last 65 kilometres from Erstfeld to the Lavorgo substation by train and low platform trailer were a precision job and required the utmost concentration. The transport started on 22 December 2010 in Austria and from their travelled by waterway via the Danube harbour in Linz to Birsfelden, and then onwards by train to Lavorgo. The transformer group should go into operation in August 2011.

The transport planning took more than two years Throughout the night employees of Swiss Railways SBB Cargo and of the heavy load transport specialist company Felbermayr performed precision work. At low speed, the 120 metre train, with the transformer in the centre on a so called Schnabel car with 20 axles and a total weight of 326 tons, rolled through many curves and slopes and over the Alps. For the SBB it was the largest and heaviest transport that ever rolled through the Gotthard tunnel. Because of the great weight the transport could not be done by road, but only by special freight wagons of the Felbermayr company. Because of the width, the height and the weight of the transformers the whole route, especially the many tunnels through the Gotthard and the structure of the railway bridges, had to be examined and measured exactly. Since due to safety reasons, no oncoming freight trains were allowed to pass during the transport between Erstfeld and Lavorgo, the transport on this stretch took place at night. The transport planning took more than two years.

Siemens constructs the largest longitudinal and lateral control transformers for Switzerland The manufacturer Siemens was challenged to construct the containers for the single phase transformers in a transportable way – that means to adapt them to the railway requirements and to the tunnel profiles. The specialists at the Siemens factory in Weiz succeeded in doing this. They built the transformers for the transport with 11.2 metres length, 3.7 metres width, 4.4 metres height and a weight of 186 tons each. When completed in Lavorgo, the total weight of each transformer will be 315 tons and their dimensions will be 12 metres in length, 8 metres in width and 7.7 metres in height. With this they are the largest longitudinal and lateral control transformers ever to have been used in Switzerland. Three transformers together have a group performance of 800 MVA, which corresponds to 80 percent of the generating capacity of the Gösgen nuclear power station. One transformer acts as a backup. In this project Siemens acts as the general contractor for the project planning, manufacture, transport and assembly of the four transformers.

Grid expansion in Switzerland for a secure electricity supply On the one hand the Lavorgo switching station enables the transport of the energy generated in the power stations in the canton of Ticino over the Swiss transmission grid and on the other it serves as a switching station in the Gotthard and Lukmanier transmission lines. The replacement of the Alpiq 380/220 kV substation is necessary because the high voltage units, especially the transformers, have reached the end of their lifespan. The responsibility for the planning, construction and putting into service of the new system was transferred to Alpiq EnerTrans. Since the beginning of the 1990s the former Atel and EOS, together with several other electricity companies, have committed themselves to the targeted expansion of the 220 kV grids in the Valais and Ticino cantons. The objective of the southwest Switzerland grid expansion is to provide a continuous 380 kV trunk grid from France via the canton of Valais to Lavorgo. This will mean that the power stations in the canton of Valais, for example the Alpiq Bieudron or Nant de Drance power stations, will be connected via a high-performance East-West trunk to the grids of France and Italy and later also via the Gotthard line to the consumer centres to the north of the Alps.