Eastern tunnel entrance construction plans
Construction of the eastern tunnel entrance will involve construction activity in South Yarra Siding Reserve, Osborne and William streets and within the existing rail corridor.
A tunnel boring machine (TBM) retrieval box will be required in the rail reserve between Osborne Street and the existing Sandringham line. TBMs will be used to create the tunnels linking the eastern tunnel entrance to Anzac Station and the rest of the network.
To construct the eastern tunnel entrance, rail tracks will need to be reconfigured between South Yarra Station and Chapel Street, and a decline structure will be built so that Cranbourne / Pakenham services can enter the new Metro Tunnel.
The works will increase the number of tracks in this area from four to six tracks. The rail corridor between William Street and Chapel Street will need to be widened for construction access and to accommodate the reconfigured tracks, and the William Street bridge will need to be demolished and rebuilt to accommodate the works.
The decline structure and tunnel entrance are proposed to be built via a 'cut and cover' method, which will see them excavated from the top down and the surface then reinstated over the top of the tunnels.
Key construction activities
It is estimated that construction of the eastern tunnel entrance will take around three years. Key construction activities will include:
- Preparatory works including land clearing and relocation of utilities including electrical, gas, water and telecommunications services.
- Demolition of acquired buildings.
- Construction works to widen the rail corridor to accommodate additional tracks, including demolition of the William Street bridge.
- Excavation of the decline structure and tunnel entrance construction, including retaining walls.
- Construction of the ventilation shaft, emergency access and a power substation in Osborne Street Reserve.
- Construction of a TBM retrieval box.
- Track works and the installation of signalling and communications systems.
- Site remediation including rebuilding the William Street bridge and upgrading shared spaces including South Yarra Siding Reserve, Osborne Street Reserve and Lovers Walk.