Barcelona’s Line 9, currently under construction, is very interesting for many reasons:
- It will be the longest metro line in Europe, with 48 km in total
- The metro line will be completely automated
- The construction is based on the idea of a single 12-metre wide tunnel, large enough to hold 2 tracks (plus platform) on two levels
- The stations are nearly completely enclosed inside the envelope of the tunnel
- Despite the high complexity of the line, the overall cost is quite reasonable
The metro line is almost completely contained in this single tunnel, which is wide enough to host other infrastructure: extra tracks to park trains at night, ramps to connect between the two directions, and facilities for egress and other equipment.
The tunnels are built using a giant tunnel boring machine (TBM)… The two phases of tunneling: pushing forward & installing the tunnel lining.
A Single Shaft for Each Station
At the stations, round pits, 25m in diameter connect the surface to the tunnel below.
This station access column includes several elevators, which provide access to an intermediate level between the two metro platforms. There’s also an elevator that provides level wheelchair access to both underground platforms, and a set of emergency stairs.
This means that at ground level, the impact of building stations is small – basically only the round 25m pits – so they can be built at locations that will maximize the nearby population or connections to other lines.
As for the tunnels, they run pretty deep, below all other infrastructure, which means they can go basically anywhere without disturbing existing structures and easily reach the stations, wherever they are built.