The new part of the 380-kV Berlin diagonal power link will run through a tunnel. This tunnel, with an inner diameter of three metres, should run about 15 to 30 metres beneath the surface. It will be created underground using a tunnel boring machine, a method used successfully worldwide. After drilling, the tunnel is lined with concrete wall elements (Tübbingen).
From the outside, only three shaft structures are visible along the link. An integrated tunnel rail makes easy inspection and maintenance possible. It can also be used to transport material or, in case of an accident, injured persons. If the capacity demand continues to rise, a second cable system can be installed in the tunnel.
Since 1998 and 2000, two similar tunnels have already been in service in the eastern part of the diagonal power link between the substations Mitte and Friedrichshain as well as between Friedrichshain and Marzahn. The concept of a cable tunnel within a city has proven to be successful. A tunnel protects the Berlin cityscape, effectively shields the electric and magnetic fields and enables operation and maintenance without affecting street traffic.