Sydney Airport northern tunnels reach halfway mark

TBMs Catherine and Marlene completed 50% of their journeys when they broke through at the Claremont Meadows services facility shaft. They were launched from the Orchard Hills Station site in July and August 2023 respectively.

Tunnelling at an average advance of 120m a week, the TBMs are digging the twin 4.3km tunnels to the new St Marys Metro Station site.

They have removed 600,000 tonnes of spoil so far, and installed 17,820 precast concrete segments as they tunnelled under the M4 motorway to the 21m-deep services shaft.

The TBMs will now traverse the 16m-diameter services shaft, before being relaunched to complete their journey. They are expected to reach St Marys in the middle of this year.

Another two TBMs, Eileen and Peggy, are building the two 5.5km southern tunnels from Airport Business Park to the Aerotropolis. Both are about 3km into their journeys and are due to arrive at the Aerotropolis late this year.

CPB Contractors and Ghella Joint Venture was awarded the tunnelling contract in December 2021.

The 23km-long Sydney Metro – Western Sydney Airport will become the transport spine for Greater Western Sydney. The line will be operational when the new international airport opens for passenger services. The journey between St Marys Metro Station and Aerotropolis Station will take around 20 minutes.