The world's first subway network was built in London more than 150 years ago. Today, at 402 kilometers, the London Underground has the longest route in Europe. Every day, around 4.8 million people travel on the Tube on the extensive routes in the tunnels beneath London's busy streets. The number of passengers is constantly increasing. New train control technology is therefore to be implemented across the entire route network to enable shorter train sequences. The "Four Lines Modernization Project" (4LM), currently the largest rail infrastructure project for the modernization of signalling systems worldwide, is the first step in this direction. It includes the installation of new train control technology on the Circle, District, Hammersmith & City and Metropolitan subway lines. Together they account for 40 percent of London Underground's traffic.

The demands on the technology are high, as Detmar Saalmann, Global Segment Manager Transportation at the Detmold-based electrical engineering company, knows: "The humid environment in the underground tunnels as well as strong temperature fluctuations require special housings with specially manufactured ventilation drains and seals." In addition, it must be ensured that the train drivers are not dazzled by sunlight reflecting off the housing surfaces when they are installed above ground. "These challenges were taken into account when manufacturing the special housings and a low-reflection stained surface was developed," continues Saalmann.

The working conditions in London Underground make the project partners' job more difficult, as the modernization work has to be carried out during ongoing operations. "In addition, the new equipment must be compatible with the existing infrastructure, some of which is over 150 years old, and have a minimum service life of 40 years," explains Saalmann.

At the end of 2019, London Underground passengers will be able to experience the first results of the modernization work when the new train control technology goes into operation on the Circle line. But the 4LM project is just the beginning of a series of modernization projects for London Underground: all other lines of the transport system will follow by 2024. When all the work is finally completed, London Underground passengers will be able to enjoy the benefits of the modernizations for many decades to come and travel quickly from one place to another in London. This is also thanks to the exceptional protection of the new signaling systems with technology from Detmold.