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Asset sale to fund underground Sydney LRT link 17 June 2014
Peter Kenyon, TunnelTalk
Sydney Rail Transit Project includes 12.5km of twin running tunnels and a harbour link

Fig 1. Rail transit project includes 12.5km of twin running tunnels

Plans to construct a second harbour tunnel in Sydney are being fast-tracked by the State Government of New South Wales as part of a Aust$20 billion road and rail infrastructure plan that will be funded by the sale of electricity transmission and distribution companies that currently belong to the State.
A TBM-bored twin tunnel Sydney harbour crossing is announced as part of a 35km rail link that will connect the 38km North West Rail Link (NWRL) between Cudgegong Road and suburban Chatswood, north of Sydney harbour, with services in the south and south west of the city (Fig 1).
The tunnel will be part of the newly announced Sydney Rapid Transit Project, which aims to increase capacity through the State capital city and remove a major bottleneck in the city’s network. The project comprises:
  • construction of 12.5km of twin running tunnels under the heart of Sydney, including the new harbour tunnel;
  • upgrade of 13.4km of existing track in the south western suburbs, and the laying of 3km of new track between Chatswood and St Leonards in the north west to complete a 73km long rapid transit line;
  • construction of five new underground stations, three of them in the heart of Sydney’s Central Business District; and
  • upgrade of 13.4km of existing line between Sydenham and Bankstown to be compatible with the rapid transit train service.
Announcement of the LRT project justifies the much-criticised decision to design the 15km of twin running tunnels that comprise the major part of the 38km Aust$8 billion NWRL for use by single-decker, rapid transit style rolling stock.
The first of four NFM TBMs that will excavate the tunnels on that project is due to go into the ground in October (2014). Project completion of the NWRL is scheduled for 2019.
Harbour crossing to a depth of 40m through sandstone

Fig 2. Harbour crossing to a depth of 40m

By using a lighter rapid transit type of train the underground stations on the new 12.5km central Sydney tunnel will not need to be excavated as deeply, and the station caverns will not have to be as large as they would need to have been to cope with the shallower gradient and size demands of the heavier double-deck passenger rail services that predominate in Sydney. A rapid transit rail solution for the underground link through central Sydney will enable a steeper gradient into and out of the 40m depth of the harbour tunnel section (Fig 2), enable construction of underground stations in the nearby CBD, and enable transit compatibility with the NWRL.
Launching the Rebuilding New South Wales (NSW) Plan earlier this week, NSW Premier Mike Baird said: “Projects to be funded include a new harbour rail tunnel in Sydney, which will dramatically improve capacity across the rail network, and a number of enhancements to the Sydney road network.”
References
New harbour crossing in Sydney’s rail plan TunnelTalk, June 2012
Four TBMs for Sydney's $8.5 billion rail linkTunnelTalk, April 2012
Sydney awards billion dollar rail mega-projectTunnelTalk, April 2013
NFM sweeps Sydney North West Rail Link TBM orderTunnelTalk, September 2013

           

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