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Emission-Free Public Transportation: City Buses in Vienna

Europe’s first fleet of electric buses is now operating emission-free in Vienna. The Austrian capital’s first electric bus, supplied by Siemens and Rampini, has been brought into service by "Wiener Linien", the municipal public transit company. By summer 2013, lines 2A and 3A will be served exclusively by twelve electrically operated buses.

Initial Situation

As with most other large cities, Vienna is troubled by air pollution, noise and congestion. Consequently, city authorities are considering more and more climate-friendly public urban transportation systems. As bus services are an essential part of urban transport, there are many possible uses for electric buses with high-performance energy storage systems.

Customer Challenges

With twelve electric buses, the Vienna public transport company Wiener Linien plans to shift two of its city bus lines completely to electrical operations by summer 2013. For this purpose, Wiener Linien has put the first fully-electric, series-produced buses in operation in Europe. Each of these routes is six to seven kilometers long.

Our Solution

Siemens has developed the concept and the drive technology for the electric buses, whose complete power requirement is supplied by the on-board battery system. The core of the system is the water-cooled electric drive motor. Whereas conventional diesel engines have an efficiency of about 25%, this three-phase motor achieves efficiency levels of about 90%.

Nine batteries with lithium-ferrite cells with a total capacity of 96 kilowatt hours supply the electric motor with enough energy for up to 120-150 kilometers. An IGBT power inverter from Siemens converts the direct current from the batteries to alternating current for the motor. An efficient battery-management system is provided to control the batteries and to monitor battery temperature and voltage.

For the scheduled service in Vienna, the vehicles have the latest charging technology: At end stations, the buses use an extendable pantograph to connect to the electrical supply for the Viennese tram system. Thanks to their regenerative braking systems, the electric buses can also recover energy. As soon as the driver takes his foot off the accelerator, the energy recovery system is activated.