First track to be laid on Metro Tunnel

(Photo by Harrison Haines from Pexels)

Crews are preparing to lay the first track in Melbourne’s Metro Tunnel project, following the completion of the tunnels.

Work on the rail tunnel and station fit-outs have been ramping up since four tunnel boring machines finished the 9km-long, 6.3m-high rail tunnels in May 2021, excavating more than 600,000 cubic metres of rock and soil.

The first of almost 40km of rail has been delivered to the Metro Tunnel’s western entrance as works gear up to install rail systems and tracks through the project’s twin nine-kilometre tunnels.

Inside the tunnels crews are fixing brackets and cable trays to the tunnel walls to hold electrical and communication cabling in place, as well as installing fire safety pipework and signalling equipment.

Specially designed gantries with bespoke “zero gravity” lifting arms travel along the length of the tunnels on wheels, allowing workers to carefully manoeuvre the equipment into place as they go. These machines make working on the project much safer by reducing the need for manual handling.

Across the 18 kilometres of tunnel, workers will install almost 50,000 brackets, 15 kilometres of elevated steel walkway for emergency and maintenance access, almost 500 kilometres of electrical and fibre cables, 16 kilometres of pipework to carry fire retardant, and more than 3000 lights.

Installing the track will take up to a year, beginning with crews laying 4000 precast concrete panels through the twin 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 30 metres underground.

The concrete panels require significantly less maintenance compared to conventional surface railway tracks, which use sleepers laid on ballast.

From mid-2022 crews will install 165 metre lengths of steel rail, progressively clipping them to the concrete panels and welding them together to form a continuous rail line along the length of the tunnels.


Read more at Inside Construction