News Articles | 10 August 2017

In the project's biggest milestone to date, the first of two tunnel boring machines has now begun its 8km underground journey from Forrestfield to Bayswater.

 

TBM Grace, named after a local schoolgirl undergoing treatment for leukaemia, will bore the first of the two tunnels. Grace's peers submitted her name in the TBM naming competition because she is the toughest person they know - a quality which TBMs also need.

The second TBM has been named Sandy, short for sandgroper. Year 4 student Sarah Spratt was inspired after finding a sandgroper in her backyard. The local insect is “excellent at tunnelling, just like the TBM”. Sandy is currently being assembled onsite and will soon be lowered into the 12m-deep dive structure at Forrestfield ready to start tunnelling in September. 

Grace starts tunnelling

On Sunday 30 July Premier Mark McGowan and Transport Minister Rita Saffioti joined our TBM competition winners at the Forrestfield dive to switch on TBM Grace. Grace McPhee for whom the TBM is named, was on hand to give the official ‘GO’. For more from the launch view the Premier’s video of the day.

TBM Grace will be operated by a tunnelling crew of 18 during 24/7 operations. This includes monitoring the TBM’s thrust force, face pressure, temperature, greases, grout and the amount of excavated soil. International tunnelling experts will train local employees throughout the project, so by the time the tunnelling is complete WA will have a local workforce capable of delivering future tunnel projects.

Dive structure supports start of tunnelling

The TBMs begin tunnelling from the Forrestfield dive structure, which took seven months to construct. The structure is 260m long and up to 22m wide, and if turned on its side would be taller than any building in the Perth CBD. A total of 14,000m3 of concrete was used in its construction. View time-lapse footage to see how the dive was constructed. 

Preparation of the Forrestfield construction site east of Dundas Road is also progressing well. Key infrastructure, including a slurry separation plant, grout plant and water treatment plant, is now fully installed and ready to support TBM operations over the life of the project. 

Excavation begins at Airport Central 

Despite the recent wet weather, diaphragm walls were completed last week for the Airport Central station box. Excavation has commenced to remove soil from within the box and this will be ongoing for the next six months. When excavation is complete the station’s concrete base will be poured to seal the structure. Construction of the station box must be complete prior to the arrival of TBM Grace in early 2018.

Equipment used to build the d-walls at Airport Central will now move to the Belmont Station construction site to repeat the process for its underground station box.  

Bayswater works on track

Work on the 500m long retaining wall being constructed adjacent to Railway Parade in Bayswater is now almost complete. After all panels of the wall are in place backfilling will commence. This involves using 12,000m3 of spoil to create an even gradient for the temporary Midland line. Backfilling, due to start next week, will take approximately six weeks to complete at which time rail construction activities will commence.

In addition to these works in Bayswater, site establishment works is also underway within the southern construction area, where the Bayswater Junction will be built. Works to date have included installing temporary fencing and removing topsoil from the site.

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