The „Albaufstieg“ as the central section of the new Wendlingen–Ulm rail line – part of the major Stuttgart-Ulm project – starts with the 8806 m long Boßler Tunnel, which is linked with the two Filstal valley bridges. The Albaufstieg section concludes with the 4847 m long Steinbühl Tunnel .
The Steinbühl Tunnel, which is devised as a twin-tube structure for safety reasons, begins in the Filstal at Mühlhausen in the valley at a height of 642 m ASL. Then it rises from the Todsburg portal with a grade of 17–24 ‰ by 105 m to reach a height of 747 m ASL (Fig. 1).
The tunnelling work...