The Prag Tunnel is a railway tunnel in the German city of Stuttgart under the Prag, a ridge between the Stuttgart basin and Feuerbach. The two 680 metre-long bores of the tunnel connect Stuttgart North station with Feuerbach station. Trains from Stuttgart run through the tunnel towards Karlsruhe, Mannheim and Heilbronn on the Franconia Railway and the Mannheim–Stuttgart high-speed railway and towards Ludwigsburg and Leonberg on the Stuttgart S-Bahn.
The tunnel runs in layers of Gipskeuper rock, containing anhydrite, which swell strongly when in contact with water. The track centres in the two tubes are 3.70 and 4.00 m apart.
Wikipedia https://en.wikipedia.org/wiki/Prag_Tunnel
Address 17 Maybachstraße, Stuttgart 70469, Germany
Coordinates 48°48'34.568" N 9°10'35.938" E
