The status plan and fire safety plan
Once an underground line has been build, another plan is drawn up: the status plan. This documents the current state of the buildings, the electricity and communication lines, and the…
Elevated underground lines
None of the planned U2/U5 routes will be elevated, largely because the urban area above is far too dense. It was possible to have parts of the U1, U2 and…
The cut-and-cover tunnelling method
In the cut-and-cover method, a digger or a milling machine cuts slots in the ground that are then filled with concrete. These will later form the side walls of the…
The New Austrian Tunnelling Method
In contrast to the cut-and-cover method, the New Austrian Tunnelling Method (NATM) is a mining technique that was first used in 1955 when building a tunnel for an Austrian hydropower…