Ever wondered how Stuttgart managed to thread a railway line right under a royal castle? That’s the story of the Rosensteintunnel. This isn’t just one tunnel. It is a series of tunnels each with its own tale.
The first Rosensteintunnel was a marvel of its time. Picture this. It was the 1840s. Stuttgart was eager to connect to Cannstatt by rail. Carl Etzel planned it. He decided to bore straight under Rosenstein Castle. People worried that the construction would damage the castle. King William I approved it anyway.
Construction began in 1844. It finished in 1846. This first tunnel was 362 meters long. It was built for double tracks. A water and mud intrusion caused delays. Leaky basins around the castle were to blame. Workers had to remove slurry and seal the basins.
After new tunnels opened in 1915, the old Rosensteintunnel was retired in 1916. It became a mushroom farm from 1931 to 1965. During World War II, it served as an air raid shelter. Mahle GmbH rented it until 1946. The Bad Cannstatt portal was sealed in 1966. Today, EnBW has underground facilities inside the portal near Stuttgart Central Station.
In the 1990s, it was declared part of the railway network and not abandoned. The state of Baden-Württemberg took ownership in 1992. There were even considerations to turn it into a mineral museum. You can still visit it occasionally today.
Then came the second Rosensteintunnel. The Stuttgart rail network was rebuilt in the early 20th century. The line between the Central Station and Cannstatt needed four tracks. The new tunnels were built a bit further east. These twin-track tunnels are each 331 meters long. Construction took place between 1912 and 1914. The first tunnel opened in November 1915. World War I slowed things down. The third and fourth tracks from Bad Cannstatt to the Central Station opened in 1925.
But the story of the Rosensteintunnel doesn’t end there. As part of the Stuttgart 21 project, another railway tunnel is planned. It will replace the current Rosensteintunnel. Preservation of the existing tunnel was considered. But it was rejected. Keeping it would mean the railway network would continue to divide the lower castle garden.
This new 3.4 km long tunnel will run from the new Neckar Bridge to the existing S-Bahn tunnel at the Central Station. It will start as two twin tubes. One will carry the S-Bahn. The other will carry long-distance tracks. These tubes will cross under Ehmannstraße. After crossing, each tunnel will branch into two single-track tubes. A branch from Stuttgart North station will connect to the existing S-Bahn infrastructure. Near Mittnachtstrasse, tracks from Stuttgart North and Bad Cannstatt will merge before connecting to the S-Bahn trunk line tunnel at the Central Station.
Let’s not forget the B 10 road tunnel. A 1,050-meter road tunnel was built under Rosenstein Park. It has two two-lane tubes. Stuttgart City Council approved the project in 2010. It cost 456 million. It opened in March 2022. The road tunnel construction included rebuilding the Berg and Schwanenplatz road tunnels.
So, the next time you pass by, remember the Rosensteintunnel. It is more than just a tunnel. It is a layered story of innovation, adaptation, and Stuttgart’s relentless march forward.