Installation of rail in the Metro Tunnel took about 9 months, and was completed at the end of March 2023.
Crews first began laying 4000 precast concrete panels along the twin 9km tunnels. There are 300 different panel shapes, to account for the varying curvature and elevation of the tunnels as they wind from Kensington to South Yarra up to 30m underground.
The high-performance panels are similar to those used in other world-class metro systems. They require significantly less maintenance compared to conventional surface railway tracks, which use sleepers laid on crushed rock.
After the precast panels were installed, steel rail was clipped on in 165m lengths and then welded together to form a continuous rail line.
Floating slab track
In areas of the tunnel where extra protection from noise and vibration is needed, floating slab track has been installed.
These specialist precast concrete panels are common in large transport infrastructure projects where the tunnel depth is shallow – for example, at tunnel entrances.
Floating slab track has pads underneath which absorb train movements, reducing noise and vibration felt at ground level as trains travel through.
The floating slab track used in the Metro Tunnel is manufactured in Victoria.
Other tunnel equipment
Much more equipment is needed to safely operate passenger services in the Metro Tunnel. Other tunnel fit-out works include installing electrical and communication cabling, fire safety pipework and signalling equipment.
In total, the 18km of combined tunnel fit-out includes:
- almost 50,000 brackets
- 15km of elevated steel walkway for emergency and maintenance access
- almost 500km of electrical and fibre cables
- 16km of pipework to carry fire retardant
- more than 3000 lights.