Solar-powered Technology for the Swiss Railroad

In a contract scheduled to run until 2017, some 430 switch towers and over 9,000 signaling elements are to be upgraded in line with the European Train Control System (ETCS).

More than half of the lineside electronic units supplied are to be powered exclusively by solar cells and will therefore be energy self-sufficient. Compared to an installation of conventional solutions, this will result in power savings for SBB of over 850,000 kilowatt-hours a year. The order is worth a total of €125 million and also covers support for the installed signaling systems over a period of 25 years.

Train control systems supplement the visible signals used to inform train drivers whether they can proceed and the speed at which they may travel. Such systems also transmit signals by radio and, if the driver does not react, automatically apply the brakes of the train. There are currently around 20 incompatible train control systems in use on Europe's railroads. As a consequence, locomotives often have to be switched at borders. The ETCS creates a standard and is used for all new installations. Any upgrades of existing track and trains are carried out as required.

Trainguard from Siemens Mobility and Logistics provides a complete portfolio of solutions for fitting trains and tracks with ETCS-compatible equipment. The elements of the system include so-called Eurobalises — radio beacons mounted on the track to transmit data to an antenna fixed under the train — and lineside electronic units, which transmit information to the balises.

Faced with the need to upgrade its existing signaling systems, SBB opted to switch to ETCS. One major challenge is to replace existing train control systems without a power supply. These serve to transmit a total of three signals — “Go,” “Stop,” and “Warning” — to the train via magnetic induction. To solve this problem, Siemens has developed a lineside electronic unit equipped with solar cells that generate sufficient energy to transmit information.

This solution not only reduces overall electricity consumption but also saves the cost of installing cables to over 5,000 signaling elements. In areas where more complex data, such as speed information, has to be transmitted, conventional lineside electronic units have been installed. The upgrade will also implement a standard for the switchgear installed in 430 switch towers, where three generations of technology are in use.