TUNNELLING for the $1.86 billion Forrestfield-Airport rail link will start in July.
Workers are digging to a depth of 14m at a “dive site” in Forrestfield where two 600 tonne tunnel-boring machines will be lowered.
It follows the arrival of the first $20 million machine at the future Forrestfield station site last week.
The machine, one of only nine in the world, was made by German company Herrenknecht and spent nine months in China for initial assembling before arriving at Henderson and being trucked to Forrestfield.
It will be craned into the “dive” structure at Forrestfield for its two-year journey.
The other machine is expected to arrive in July.
Each will dig 8km of 7m-diamater tunnels from Forrestfield under the Swan River, Perth Airport and Guildford Road to Bayswater and a spur off the Midland line.
“The machines will tunnel under Perth Airport and the Swan River, reaching a depth of 25m, and the conditions underground on the route are incredibly diverse, ranging from sandy material to clays and rock, all under water,” Transport Minister Rita Saffioti.
Salini Impregilo-NRW Joint Venture was award the contract for the project in April last year, which includes a 10-year maintenance period after it is completed in 2020.