The West Metro commuter traffic line that is in use from Ruoholahti to Kivenlahti is 21 kilometres long. The metro has two rail tracks: one to the east and one to the west. Two parallel underground tunnels run the entire length of the rail section owned by Länsimetro, from Ruoholahti to Kivenlahti. The width of a tunnel is six metres. The distance between the tunnels varies between 13–17 metres. At turnaround tracks, the distance may be a maximum of 50 metres.
An underground metro line and its stations leave space above ground for other uses, such as residential and other construction. The operation of an underground metro is more secure than an above ground one, because, for example, the underground metro is unaffected by weather. Also read: Why doesn’t the metro run above ground?
Separate tunnels ensure that if a fire breaks out, it can be contained in just one tunnel and commuters can safely access the adjacent tunnel via a fire-compartmented connecting tunnel. These connecting tunnels are located roughly every 150 metres in between the two parallel metro tunnels.
In the rail tunnels of the West Metro there are 1.2-metre-wide emergency exit platforms which provide safe passage in emergency situations, such as a fire or a power outage, from anywhere along the metro train to the metro station or to the other tunnel via the connecting tunnel. Only a handful of metros around the world are equipped with such emergency platforms.
The West Metro’s systems also ensure safe commuting
Two parallel underground tunnels run the entire length, from Ruoholahti to Kivenlahti.
The length of the West Metro line is 21 kilometres.
The metro track from Ruoholahti to Kivenlahti is a total of 46.3 kilometres. In addition to the rail line use for commuter traffic, the total rail line also includes turnaround tracks and the section leading to the metro depot.
There are 72,500 sleepers on the West Metro’s rail section. The purpose of sleepers is to evenly distribute the metro train’s weight on the support layer built of ballast.
There are 92,450 tracks on the West Metro section. The tracks are installed on sleepers, and the metro trains travel along them.
There are a total of 84 turnouts and crossings on the West Metro section.
There are a total of 9,100 retaining wall elements. Retaining wall elements have been installed along the entire length of both tunnels. The top of the retaining wall elements serves as an emergency exit and contains technical systems.
Connecting tunnels are located roughly every 150 metres in between the two parallel metro tunnels. There are a total of 102 connecting tunnels.
There are altogether 17 maintenance tunnels. As the name implies, these tunnels serve as passageways for the non-routine maintenance of the metro stations and rail line.