Engineering, Passenger Rail

Second TBM gets underway at Forrestfield

A second tunnel boring machine (TBM) has begun its work on Perth’s $1.86 billion Metronet Forrestfield-Airport Link project.

This is the second of two TBMs that have been specifically designed for the Forrestfield-Airport Link by German company Herrenknecht, with components manufactured around the world and assembled and tested in China before arriving in Western Australia.

The first TBM, nicknamed “Grace”, was launched in July for its two-year journey underground to Bayswater, where the new line will spur off the Midland Line. Moving at a rate of approximately 20 metres per day, the machine has now has now travelled around 620 metres into the earth.

Now the second TBM, nicknamed “Sandy”, has begun tunnelling at Forrestfield, having been launched from the 12-metre-deep dive structure at the site of the future Forrestfield Station on Tuesday.

The two 600-tonne, 130-metre-long TBMs will tunnel 8 kilometres under Perth Airport and the Swan River, linking new stations at Forrestfield, Airport Central and Belmont.

“From now on, as the construction of the three train stations on the Forrestfield-Airport Link ticks on above ground, underneath the surface Grace and Sandy will be boring and reinforcing the foundation of the tunnels which trains will run through in only three years’ time,” state transport minister Rita Saffioti said.

“It’s yet another landmark on this exciting, job-creating, suburb-transforming Metronet project.”

Diaphragm walls that will house the station box structure have now been constructed at the Airport Central site, and soil within the walls is beginning to be excavated. At Belmont, diaphragm wall construction is almost complete.

TBM Grace is expected to break into the station box at Airport Central Station in early 2018, followed by TBM Sandy not long after. The two machines will finish their tunnelling journey in Bayswater in April (Grace) and June (Sandy) 2019.