Three internationally renowned firms in civil construction are vying to deliver a mega-tunnelling contract as part of a new rail project which will help to reshape Greater Sydney and connect the new airport with the city’s growing western suburbs and the CBD.
NSW Minister for Transport Andrew Constance has announced that three consortia have been shortlisted to deliver the box and tunnelling work on the Sydney Metro – Western Sydney Airport project.
The bidders are:
- Bouygues Construction Australia Pty Ltd
- John Holland Gamuda Joint Venture
- Acciona Construction Australia Pty Ltd
Part of the mega Sydney Metro development, the Sydney Metro – Western Sydney Airport project will deliver 23 kilometres of new metro line and six new stations between the new Western Sydney International Airport which is set to open in 2026 and St Marys station in Sydney’s growing west.
From St Marys, commuters will be able to transfer to the existing metropolitan rail line and connect with the Sydney CBD.
Around ten kilometres of the new line will be delivered through underground tunnels. Remaining sections will be delivered via surface track and viaducts.
There will be two sections of twin tunnels.
The first will run in the northern section from St Marys to the Orchard Hills portal near Orchard Hills Station (see map).
The second will run in the southern section from the Airport Business Park down to the Aerotropolis via the new airport.
Four tunnel boring machines will be used.
Of these, two will be launched from the Orchard Hills Portal and will bore their way underground until they reach St Marys.
The other two will be launched from the Airport Business Park and will bore their way to the Aerotropolis.
Each TBM will be approximately a similar length to two Airbus A390s and will weigh around 700 to 900 tonnes – a similar weight to around 570 large cars.
As well as digging, the TBMS will insert segments which will line the tunnels as they go along.
A proposed tunnel alignment has been detailed in the project Environmental Impact Statement which was released last October.
The alignment will be refinement as further site investigations reveal more about ground and environmental conditions.
The precise alignment will be chosen according to considerations such as the shortest path between stations, ground conditions and existing infrastructure and buildings.
On average, each tunnel will be around 23 meters deep.
To facilitate pedestrian movement, the tunnels will be shallower at stations.
The tunnels will be supported by other facilities including:
- Tunnel portals from which the TBMS will be launched. These will support tunnelling activity will be used during construction to pump fresh air into the tunnels, extract rock and other materials from the site and to supply power and water to the machines .
- A stabling facility at Orchard Hills which will house trains as well as an operation and maintenance centre along with staff car parking. This will support the operations of the new metro line as well as the fleet maintenance.
- Service facilities at both the northern and southern tunnel sections to provide fresh air and emergency egress.
The first TBM is expected to be in the ground by the middle of 2023.
The project will support 14,000 jobs, including 250 apprentices.