News Articles | 21 December 2018

Tunnel boring machine (TBM) Grace has been very busy in 2018 reaching the halfway mark (3571m) of her underground journey in November, and clearing the airside environment in December.

TBM Sandy isn't far behind, with both machines having successfully tunnelled under the airport's two major runways. The TBMs are expected to arrive at Redcliffe Station in the first quarter of 2019.

As outlined below, works across all nine construction sites are also well-advanced and segment production is now at 85 per cent, with 7640 rings produced.

Next year will be even busier with tunnelling under the Swan River on the cards. Not to mention progressing with the construction of three stations, three emergency egress shafts and 15 cross passages.

While significant progress has been made to date, there have also been some set-backs along the way. As announced by Transport Minister Rita Saffioti on Tuesday December 18, a review of the project timeline has been conducted and first trains are now expected to run on the line in the second half of 2021.

While the budget remains unchanged, the adjustment of the completion date was necessary to allow for the construction methodology of future cross passages to be revised and rectification at cross passage Dundas to be completed.

Since a leak developed at the first tunnel-to-tunnel cross passage in September, numerous international consultants and experts have been engaged to review options for the permanent solution to rectify the damaged section of the tunnel. A section of Dundas Road is closed while remediation works are underway. Two narrow temporary lanes along Dundas Road are set to be opened later this week while works in the area are ongoing.

The year of the dive structure in Bayswater 

The most visual change of 2018 occurred at the Bayswater Junction site, where excavation of the 400m-long dive structure commenced after the construction of 133 diaphragm wall panels in April was completed.

With excavation nearly complete, works have started on the construction of the dive portal base slab, located at the eastern end of the structure.

As part of this package of works the concrete slab for the 100m-long Midland Line rail overpass was also completed, allowing the city-bound trains to cross over the Forrestfield Line tracks once the alignment is open.

In preparation for the arrival of the TBMs, a dry box was constructed in September, which will assist with preventing water ingress during the TBMs' final break-through at the end of their tunneling journey.

Another highlight included the unveiling of the 500m-long mural on the northern retaining wall, created by artist Drew Straker and 75 of his students. It is one of the longest murals of its kind in the Southern Hemisphere.

Works are now underway on the construction of the retaining walls for the future principal shared path on the southern side of the alignment.

Forrestfield Station taking shape

A major milestone for the project this year was the opening of the Dundas Road realignment in Forrestfield. The new alignment united the divided construction site and allowed backfilling of the station retaining wall on top of the old alignment to commence. Backfilling is due to be completed at the end of the year, enabling the construction of the station roof in early 2019.

Further south, construction of footings for the 150m-long station platform is underway and services have been installed at concourse level.

At the southernmost end of the site, the stowage area platform was completed and works have commenced on the stowage building which will house cleaning and maintenance equipment for the trains.

​In September, a variation to the design was announced by Transport Minister Rita Saffioti. As a result, the station precinct will feature a multi-deck car park instead of at-grade parking, allowing for eight hectares of land to be released for development opportunities close to the station. Construction of the car park will commence next year.

Redcliffe Station to be next TBM host

The year at Redcliffe started off with the excavation of the station box and construction of the ground slab for the future station building. Once some 45,000 cubic metres of soil had been removed, the construction of the 1.5m-deep base slab followed. Approximately 5500 cubic metres of concrete and 1300 tonnes of steel, along 3750 square metres of waterproof lining were used to seal the structure.

With these three major pieces of work now completed it's all hands on deck to prepare for the arrival of the TBMs in early 2019.

Near the Redcliffe site, at the location of the future cross passage at Brearley Avenue, jet grouting works were finalised in the second half of the year. The actual cross passage will be constructed below the ground once the TBMs have tunnelled past the area.

Reaching new heights at Airport Central 

All the excitement took place at Airport Central Station this year, with both TBMs breaking through into the station box and leaving Redcliffe-bound after undergoing a month of maintenance.

Before the big event was able to take place the station box had to be fully excavated and the base slab built to seal the structure. 

Once the machines and their nine trailing gantries had made their way through the box, works shifted to building access points like staircases and infrastructure required for the elevators and escalators. 

Later in the year construction commenced on the elevated entry point for the Skybridge, which will connect the train station with the airport terminals. Next year efforts will shift to constructing the steel structure and installing escalators.

Digging in at the Emergency Egress Shafts

During 2018 all three emergency egress shafts (ESS) were fully excavated and two out of three shafts had their base slab constructed.

At Abernethy EES works have even included installation of services for the portal building and the construction of the building ground slab. Abernethy EES is also the first EES that has been connected to both tunnels.

At the Airport West EES site works are currently underway to install electrical and communication services.

Excavation of 2130 cubic metres of soil at Wright Crescent EES finished in December and preparations are now underway to pour the 1.8m deep base slab that will form the foundation of the 9m wide shaft.

Tools down for Christmas

Construction will take a break between December 22 and January 6 with only a small crew operating the TBMs.

We would like to take this opportunity to thank you for your ongoing interest in the project and we wish you and your families a safe and happy festive season.

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