The Melbourne Metro rail project will tunnel 11m below the Yarra River’s surface to create two tunnels between the new CBD South and Domain stations.
The top of the twin tunnels, each around 7m in diameter, will be approximately 7m below the riverbed, east of the Princes Bridge.
According to the Melbourne Metro Rail Authority, tunnelling using TBMs was selected because it will minimise the impacts on the river and surrounding areas. Other techniques would significantly disrupt the area by either damming or creating an immersed tube tunnel, which would involve dredging of the river bed.
Melbourne Metro will deliver two new 9km rail tunnels and five new stations to Melbourne’s rail network, increasing capacity in the City Loop so more trains can run more often.
Construction on the project is expected to commence by 2018.