Forrestfield-Airport Link
Australia, Perth
2017 – 2020
Grace and Sandy bore down under

"This is the longest rail tunnel ever undertaken in Western Australian history," said Western Australia Transport Minister Rita Saffioti with visible excitement at the breakthrough of "Grace," the first of two TBMs. After 934 days, on February 18, 2020, "Grace" had her final breakthrough. The Variable Density tunnel boring machine had bored 7,610 meters through heterogeneous soils on the way from Forrestfield to Bayswater under Perth. Her sister machine "Sandy" drove a second, parallel tube and reached its final destination after 7,600 meters on April 20, 2020. They lined the two tubes with a total of 54,000 locally manufactured segments in 9,000 rings.

The tunnels built by the Salini Impregilo – NRW joint venture are the key structure of the Forrestfield-Airport Link. The new subway with its two parallel tubes will connect Perth's eastern suburbs and the international airport with the city center. With three new stations (Redcliffe, Airport Central, Forrestfield) and the connection to the Midland Line near the Bayswater station, the Forrestfield-Airport Link significantly increases the capacity of local public transport in the Western Australian city.

Manufactured by Herrenknecht at its site in Guangzhou, China, on their way from east to west the two Variable Density tunnel boring machines, with a diameter of 7,100 millimeters each, passed beneath Perth's airport in full operation as well as several major roads and the Swan River. Under the river, they reached their maximum depth of 26 meters.

For sustainable mass transit and future growth

The completed subway will allow residents of the eastern suburbs to travel to the city center in just 20 minutes – instead of 45 minutes by car. It will improve sustainable mobility and give the economy new impetus. It will help Perth adapt to the needs of a growing population: according to estimates, the number of residents in the city will increase from 2 to 3.2 million by 2030.

"The completion of the Forrestfield-Airport Link is a key feature in our METRONET plan to connect Perth's suburbs and reduce traffic congestion," said Western Australia's Premier Mark McGowan. "It's a historic milestone for the state."

Forrestfield-Airport Link

Data Sheet

Country, Location

Australia, Perth


2017 – 2020




Heterogeneous ground

Tunnelling length

15,210 m

Machine Data

2x Multi-mode TBM:
Diameter: 7,050 mm
Lining method: Segmental lining
Cutterhead power: 1,400 kW

Your contact person Contact us

Steffen Dubé President and General Manager Herrenknecht Tunnelling Systems USA Inc.
Gerhard Goisser Commercial Manager Herrenknecht Tunnelling Systems USA, Inc.