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…
Advancing with the tunnel boring machine
The tunnel boring machine is around 120 metres long, seven metres high and is also affectionately known as the ‘mole’, it bores slowly through the soil, carrying all the necessary…