The traction power supply of the Wendlingen–Ulm high‑speed rail line

On 12 December 2018, the first overhead contact line (OHL) pole was mounted on the Wendlingen–Ulm high-speed rail line construction project in Germany. On 31 January 2022 the OHL was energised; the high-speed line is now due to open for commercial operations in December 2022. Christian Lammerskitten, Head of Power Supply and Signalling at DB Projekt Stuttgart–Ulm GmbH, provides an overview of the traction power supply system for the line, from the 110 kV level to the 15 kV level.


High-speed overhead contact line on a pair of switches. Credit: Armin Kilgus

The Wendlingen–Ulm high-speed line is part of the German Rail Project Stuttgart–Ulm, which itself is part of the European railway axis Paris–Strasbourg–Stuttgart–Vienna–Bratislava and part of the Rhine-Danube TEN 17 corridor. New and upgraded high-speed lines will operate all the way from Paris to Vienna with high-speed trains capable of running up to 300km/h. By the end of 2025 the completion of Stuttgart 21, the second part of the entire Stuttgart–Ulm project, will significantly decrease the travelling time between Stuttgart and Ulm from 54 minutes to less than 30 minutes. The line is designed for a maximum speed of 250km/h.

The Filstalbahn, the existing connection that was built in the 1840s and has been in operation since 1850 from Ulm to Stuttgart via the Geislinger Steige, allows for maximum speeds of up to 160km/h, but it also has sections limited to a maximum speed of 70km/h due to a curve radius and gradients. For the new line, tunnelling was a major part of the project. Due to the protection of the landscape and a nearly direct line between the city of Ulm and the Stuttgart airport, half of the 59.5km-long line are running in tunnels.

Traction power supply

In Germany, traction power supply for main line train operations is realised with a voltage of 15kV/16,7Hz. Although the decentralised converter stations are allowed to feed 15kV/16,7Hz sections from the high voltage 50Hz utility networks, most of the electrified tracks are supplied by the 7,800km long, Deutsche Bahn (DB) owned 110kV, 16,7Hz single phase central network.

The 110kV lines are the backbone for a reliable, safe and environmentally sustainable railway operation. Currently, more than 60 per cent of the energy is produced from renewable resources. The target for DB is to increase the use of renewable energy to 100 per cent by 2038. For the Wendlingen–Ulm project, two new substations, two new switching stations, as well as two new 110kV overhead line links and more than 150km of overhead contact line have been built.