Press release - November has seen a high volume of concrete works taking place across our construction sites. At Forrestfield the future station platform walls are being poured, Airport Central Station concrete works include the construction of the slabs and beams for the entry to the elevated walkway, at Redcliffe the base slab pours are in the final stages and the first of the foundations for the cycle path retaining walls have recently been poured in Bayswater.
Tunnelling has also reached a major milestone with both tunnel boring machines (TBMs) having cleared Perth Airport's main runway. And with TBM Grace closing in on the halfway mark (3571m) and 79 per cent of tunnel segments now produced, the project is quickly approaching another two major milestones.
Meanwhile activities are continuing to repair damage caused by a leak in the project's first tunnel-to-tunnel cross passage located just south of Sorensen Road. The next stage of works will involve compaction grouting. This is a ground improvement technique where grout is placed in the ground to reinforce the soil and fill any voids, and then compacted. Ground stability assessments will be conducted at regular intervals, followed by the repair and reopening of Dundas Road. All businesses along Dundas Road remain accessible and open while these works are ongoing.
Dry box finalised at Bayswater
The construction of a dry box at the Bayswater dive portal has been completed. It is the last structure the TBMs will tunnel through at the end of their underground journey and it is designed to correctly pressurise the TBMs’ final break-throughs. Cast in-situ, piles were constructed using a cylindrical auger that was driven into the ground, then lifted while concrete was poured to fill the void. Collectively the piles now form a box which will be dewatered once the TBMs are parked in it.
A new set of works has commenced with the construction of the retaining wall foundations along Whatley Crescent. Retaining walls are required to make up for varying heights between the road, cycle path and rail.
Following an acoustic analysis to determine noise mitigation measures between the rail and adjacent properties along Whatley Crescent, a design including noise walls is being finalised. Noise walls are constructed using up to 200mm thick precast reinforced concrete panels and are designed to reflect sound up and away from residential areas. More information on the design is available on the project's website.
Forrestfield Station transforming
More progress has been made on the future Forrestfield Station platform with nine out of 16 walls on the eastern platform now completed. Preparation works have also commenced for the excavation of the station's escalator foundations and lift pits.
At the station concourse level installation of hydraulic services is nearing completion and installation of power and communication services has commenced.
The backfilling of the station retaining wall is also ongoing and scheduled to be finalised by the end of the year. This will allow for the station roof to be built in early 2019.
At the northern end of the site, at the tunnel portal, installation of formwork for the lift shaft located adjacent to the tunnel entry/exit is now underway.
The stowage area, at the southern end of the site, is also coming along nicely with the stowage building concrete slab scheduled to be poured before the end of the month to enable brickworks for the building to start.
Redcliffe Station preparing for TBM arrival
With only two of nine concrete pours left to complete the station base slab, works have started to focus on the arrival of the TBMs early next year.
This includes the removal of temporary struts to clear the way for the TBMs to pass through the station box unhindered. Also ongoing is the construction of the first section of temporary segment support blocks. These blocks will support the TBMs and their 130m long trailing gantries being maneuvered through the station box to where the cutterhead is to be lined up for the next section of tunnelling.
Access focus at Airport Central
After completing the first staircase in October the elevator pit has now also been constructed, bringing Airport Central Station one step closer to finalising access points for its future patrons.
Works are full steam ahead on the entry point to the elevated walkway, which will connect the station with the terminals. Steel fixings are currently being installed in preparation for a concrete slab pour later this month.
The first of four circular ring beams connecting the tunnels to the diaphragm walls is nearly finished and the second one is due for completion in January 2019.
Building works to start at Abernethy EES
The emergency egress shafts (EES) connect the tunnels to the ground level in the event of an incident. The shafts lead to a two-storey portal building, car park and emergency muster point.
The portal buildings house communications, electrical and mechanical equipment and controls. They also contain air vents which will help ventilate the shafts and tunnels.
Sections of the buildings are located on top of the actual shaft and contain the lifts and stairs which will allow people to egress safely to the surface in case of an emergency. The buildings are made up of about 60 precast panels that are up to six metres tall.
Works at Abernethy EES currently include construction of the ground slab for the portal building. After completion of the slab the same set of works will commence at Airport West EES. Wright Crescent EES is still at excavation stage and has reached a depth of 26m, with seven metres to go to reach base slab level.
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