Sydney Airport Link

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This 10km turnkey metro project links the city centre to Kingsford Smith Airport. The line is predominantly underground.

The works on the Sydney Airport Link tunnel beat all previous records in Australia: at the time of construction, it was the longest tunnel ever driven on the continent, the largest-diameter TBM used and the first use of a slurry-shield machine.

Constructed as a turnkey operation, this 10km metro line, linking the city centre to Kingsford-Smith airport, is almost entirely underground. The tunnel section (9km in length) includes 2.2km constructed using roadheaders in hard rock.

Another 5.5 km section was bored in soft ground beneath the water table, using a 100m long slurry-shield tunnel boring machine (TBM) with a diameter of almost 11m.

The line also has 720m of cut-and-cover tunnels and several engineering structures, including a viaduct and a tunnel beneath the Cook’s river. The 170m long stations were excavated within diaphragm walls.

In addition to the use of a slurry-shield TBM, the project required the installation on-site of a pre-casting plant for voussoirs, manufacturing 240 units per week, as well as a high-tech plant for treating excavated materials.

Two complex and innovative solutions were employed for the first time in civil engineering to prevent the cutter head of the TBM clogging up: injection of 5m3 of hydrogen peroxide into the cutter head; potassium chloride slurry replaced the normal bentonite slurry to avoid the possibility of a “crust” forming.


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