Sydney Metro – Western Sydney Airport tunnels take shape below new international airport

Tunnel boring machines (TBMs) Eileen and Peggy are building the two 5.5-kilometre southern tunnels from Airport Business Park to the Aerotropolis and are respectively 1.8 and 1.5 kilometres into their journey.  

The TBMs launched earlier in the year and have since broken through at the Airport Terminal Station site, where they spent several weeks traversing the 200-metre-long station box before being relaunched to continue tunnelling. 

Since leaving the Airport Terminal site, the TBMs have continued digging underneath the Western Sydney International Airport and have completed their second breakthrough to reach the Airport Terminal support shaft.  

The temporary shaft will support the TBMs as they continue to build the tunnels and will be used as an access point for the delivery of materials and removal of excavated rock.  

So far, TBMs Eileen and Peggy have excavated a combined 305,000 tonnes of material to build the twin railway tunnels and have installed 11,800 concrete segments to line the walls of the new tunnel. 

Both TBMs are tunnelling at an average speed of 120 metres a week and are expected to arrive at the Aerotropolis Station site in mid-2024. 

A further two TBMs have launched from Orchard Hills to tunnel towards St Marys and are about one kilometre into their journey to carve out the 4.3-kilometre tunnels at the northern end of the alignment. 

It is expected that once operational, the end-to-end journey time between the St Marys metro station and Aerotropolis Station would be around 20 minutes.