The line, entirely double-track, was officially inaugurated on 8 May 1992.
Trains have run through again on the now double-track line since 5 November.
From there the existing double-track line would be shared through the airport.
Plans later developed circa 1980 to remove the tunnel and put in a larger, double-track line.
The distance between the track centres makes a difference in cost and performance of a double-track line.
The double-track line was built from the late 1990s as a new line.
Two parallel tunnel tubes were cut through the mountain for the double-track line.
This railway branch was completed as a double-track line in 1885.
North of the Hauptbahnhof the line divides into two double-track lines.
The railway was built as a double-track main line throughout.