Tunnel Boring Machines

Tunnel Boring Machines (TBMs) are large machines that excavate below the ground surface, while simultaneously installing concrete lining units to build a tunnel. Two TBMs have been specifically designed for the Forrestfield-Airport Link by German company Herrenknecht, the world’s leading supplier of TBMs.

There are various types of TBMs to cater for different project requirements. For this project, the TBMs will be Mixshield which use the latest dual-mode technology capable of adapting to variable ground conditions, such as sand, rock and clay, as the machine progresses.

Two TBMs will arrive on site at Forrestfield in mid-2017, where they will be lowered into a dive structure and begin their two-year journey towards Bayswater.  During this 8km journey, the TBMs will excavate under Perth Airport and the Swan River reaching up to 30m depth below the surface.

To find out more about how these machines operate, view the TBM fact sheet.

Where are the TBMs now?

The TBMs are currently being manufactured overseas. Key components for the TBMs are manufactured in various places around the world before an in-depth nine month assembly and testing program is conducted in China. Once testing is finished, they will be disassembled and shipped to Fremantle Port by mid-2017.

Once tunnelling begins the TBMs will be in operation 24 hours a day. The two TBMS will be staggered two months apart to help ensure ground stability, with the first reaching Bayswater in April 2019 and the second arriving in June 2019. 

Despite their huge electric and hydraulic- powered motor drives, TBMs create little noise at the surface and cause only minor vibrations as they cut through the soil and rock in their path. If you are living near the tunnel route, you’ll be given plenty of notice and information before the tunnels are bored, but most people don’t even notice when the boring machine is directly under them.  Once the tunnel structures are complete it is unlikely you’ll even know the trains are there.

Naming the TBMs

Like ships, TBMs are named before they begin work to bring good luck.  Traditionally, a TBM cannot start work until it is given a name. TBMs, and other machines that work underground, are generally given female names as history shows that underground workers look to Saint Barbara for protection. 


The diameter of each tunnel


The weight of the TBMs