Grafenort – Engelberg Tunnel
The 245th longest tunnel in the world
The Grafenort – Engelberg Tunnel is a railway tunnel on the Luzern–Stans–Engelberg-Bahn line, which forms one portion of the Zentralbahn in Switzerland. It replaced the steepest section of the line, an inclined length of 1,600 meters that had a peak gradient of 25%, allowing for a faster transit since its completion. Following a number of preparatory surveys and assessments, construction of the tunnel commenced during March 2000. Work was delayed by two years due to a particularly severe flood that started in August 2005; it had been recognised beforehand that water ingress was a particular threat, thus the project included the construction of a concrete inner vault. The completed tunnel was officially opened during February 2010.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).