SILTY soil, the cancer centre currently being built, the City Loop’s four tunnels and aquifers beneath the murky bottom of the Yarra River are all major hurdles to building a proposed new rail tunnel beneath the city.
Investigative work is well under way on building the proposed Melbourne Metro tunnel, before the required federal funding to help pay for the major project has been secured.
But project planners have yet to solve a number of engineering challenges, the greatest of which is how to tunnel beneath the Yarra River, which is risky due to the presence of aquifers and softer ground.
Cracks have previously appeared in CityLink’s Burnley tunnel near the river, leaking water and costing hundreds of thousands of dollars to repair.
Public Transport Victoria is also contemplating running the tunnel over the City Loop near Melbourne Central station, just metres below the earth’s surface.
This option is preferred as it would cost less than digging beneath the Loop, some 50 metres below ground . . .
Public Transport Victoria was also contending with changes brought about by the construction of the Victorian Comprehensive Cancer Centre in Parkville…
Further west at the proposed Arden station in North Melbourne, the presence of silty soil meant watertight diaphragm walls would be needed . . . while sandy soil at Domain station beneath St Kilda Road was also a potential problem.
Adam Carey, The Age, February 28, 2013