Spectators at this month’s Olympic Games may well make part of their journey into Sydney on the Airport Link railway, opened in May. It is otherwise known as the New Southern Railway (NRS).
"The connection was not built specifically for the Olympics, even though it serves the airport, which has undergone major upgrades on both domestic and international terminals," says Ted Nye, a consulting engineer who has been working for the tunnel client, the Rail Access Corporation. "It is destined to link the suburban areas and encourage consolidation of what is now a rather sprawling city."
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But the project does synchronise well with the events that have turned the world’s eyes on to the country.
Four of five new stations along the route shown are underground (figure 1). The line passes through areas currently used at the surface as a mixture of light industry and low-level residential houses, especially north of the airport. An exception to this is a short section of commercial high-rise buildings just to the south of Mascot Station.
"Like many Australian cities, Sydney is jammed between the sea and the mountains," says Craig Covil from Ove Arup, who worked on the Cook’s River crossing section of the project. "It needs to concentrate its growth." The river crossing is part of the Southern Structures.
Arup, which undertook the design and documentation of cut-and-cover tunnels between Tempe Reserve and Turrella, is one of a group of five of Australia’s leading consultants on the project.
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By GlobalDataOther designers were: Connel Wagner for some 2.5km of hard rock tunnel; Hyder for the stations at the two airport terminals; Maunsell for Mascot station; and Bouygues on the concrete segment design for the 6km of soft-ground tunnel.
In total, some 11km of line, mostly in twin-track, single-bore tunnel, runs from the airport to the downtown central business district, with trains continuing on along the East Hills Line. There are also sections of cut-and-cover tunnel and approach ramps.
All these areas could develop as a result of the line, and as they do so they will have to follow strict construction measures that Ted Nye outlines opposite. The unusual controls are needed to preserve tunnel integrity and long-term leakage control.
The rock tunnel excavated material generally
consists of sandstone, although the initial driven section at the north portal was excavated in stiff clay and shale.
The airport’s international terminal, domestic terminal and Mascot Station, just north of the airport, have been constructed using the top-down and diaphragm-wall method. Green Square Station has been excavated in sandstone rock at platform level using driven tunnel techniques with diaphragm walling in soft ground in the booking hall and entry levels above. The groundwater table is a few metres below the surface along most of the route.
The client for the scheme started the project as the State Rail Authority, but a privatisation process split responsibilities as the project developed.
Covil explains: "The NSR project is the result of a unique combination of public and private-sector
involvement in its planning, development and realisation.
"Concept planning and detailed feasibility stages were undertaken by the Airport Link Association, which was formed by CRI, Transfield, CityRail and the NSW Department of Transport.
"The project was evaluated by government agencies, which included the Premier’s Department, the Department of Urban Affairs and Planning, Treasury, the State Rail Authority and the Department of Transport.
"The next step was that the assets were split. The public sector would fund and own the tunnels, track, catenary, signalling and communications system – much as Railtrack owns and is responsible for fixed-line assets in the UK. The Wolli Creek Interchange Station is also publicly owned.
"Then the private sector will have a 30-year lease concession to fund, own and operate the stations at Green Square, Mascot and the two airport stations at the domestic and international terminals," says Covil.
"Part of the arrangement negotiated is that the private sector would design and construct the whole project and the companies would have a period contract to maintain the public-sector component of the project."
This means that all stations except Wolli Creek are owned and operated by Transfield Bouygues until they revert to SRA after 30 years.
Tunnels and track, which remain in public ownership, were awarded to the Transfield Bouygues Joint Venture (TBJV) as a design and construct project. The JV will also carry out maintenance under a period contract.
Before the work had reached this implementation stage construction, Arup had already been commissioned for work on the scheme. The State Rail Authority used the firm in 1995 to conduct an independent assessment of the financial and technical aspects of the project and act as adviser to the state government.
Throughout the scheme the main representative for the SRA has been Kinhill Engineers (now Brown & Root. Their work included administration, on
behalf of the RAC, of the design and construction contract.
Related Files
Sydney Airport and Railway System
