Unfortunately, the project's two tunnel boring machines (TBMs) have been stationary for the past few weeks with repair works ongoing. Following damage to TBM Grace's screw conveyor, the part that moves excavated material away from the front of the machine, cracks were also identified in TBM Sandy's screw conveyor.
Specialist welders from TBM manufacturer Herrenknecht have been flown in and are currently conducting repair works to both machines. Works are expected to be completed later this month, with Grace and Sandy due to arrive at Redcliffe Station mid-year, where they will be fitted with brand new screw conveyors.
Meanwhile segment production is on the home stretch with less than 400 tunnel segments (about four per cent of the total number required) left to be cast.
Busy bee at Bayswater
The southern retaining wall, part of the structure enabling the city-bound Midland Line to cross over the Forrestfield Line, is in its final stages of construction, with the last section of the wall now curing. Next up is backfilling of the area between the dive structure's diaphragm wall and the retaining wall with 4800 cubic metres of soil.
Looking to the west, work has begun in preparation for the construction of two retaining walls which will support the principal shared path (PSP). The first of the walls will be completed around May; works will then commence on the second wall.
The base slab is progressing well with seven of the 18 sections now poured. Preparations continue on the remaining sections, including blinding and installation of waterproofing materials.
At the eastern end of the site the construction team is currently removing the temporary struts near the tunnel portal, where the TBMs will break through at the end of their tunnelling journey.
Redcliffe ready for breakthrough
In preparation for the arrival of the TBMs, recent activity at Redcliffe Station has included installation of service pipes along the station’s walls. The pipes will be removed after tunnelling is complete.
At ground level, work is underway on the base slab for the tower crane. Once the TBMs leave Redcliffe, the crane will be used to lower tunnel segments into the station box, from where they will be carted to the TBMs by multi service vehicles (MSVs).
Clearing has been undertaken for the station’s car park, located near Central Avenue and Second Street. Work has also commenced to build a new limestone retaining wall and Colorbond fence along the boundary of neighbouring properties.
Steelworks starting at Airport Central
Airport Central Station's concourse level, where the station’s ticketing facilities will be located, is getting infilled. The area was left open to allow for materials to be lowered to the base level, but the time has come to close the gap. Trusses have already been placed around the tunnel openings to create the foundation for the formwork and once all the nuts and bolts are tightened, 140 cubic metres of concrete will be poured.
The segments which guided the TBMs through the station last year will be removed in the coming weeks, with the thrust frames used to launch the machines already removed. This will allow for the finishing touches to the tunnel entry and exit points to be completed.
Another milestone was reached recently with the delivery and installation of the first part of the station's steel structure. The steel column connecting the 15m-high and 35m-long escalator was successfully placed and filled with concrete. Once operational, it will take 55 seconds for the trip from top to bottom of the escalator.
Infrastructure focus at Forrestfield
A number of crews are currently located at the Forrestfield site, progressing different sections of the infrastructure required for the station.
In the stowage area, the 130m-long platforms have been completed and construction is continuing on the stowage building. The building’s steel roof is now in place and installation of roof sheeting is underway.
At the future station, steel fixing for the sixth section of the concourse slab is underway. The pour for the final concrete slab (which is a suspended slab) will follow after the completion of other works, such as the wall structures for the passenger elevator pits.
With casting and curing of the floating slab for the portal building at the northern end of the site complete, the lift shaft is now being raised another level and blockwork for the building has commenced.
Tunnelling between the tunnels
Waterproofing works inside the Wright Crescent emergency egress shaft (EES) are approaching completion with the base slab due to be poured in early April. Outside the shaft, preparations for the ground slab are ongoing with the installation of conduits for services such as power, water and firefighting systems.
Excavation of the first cross passage for the Airport West EES has begun from within the shaft. The cross passage, connecting the shaft and Tunnel One, is expected to be fully excavated by the end of the month. The same works will begin for Tunnel Two once the final gantry of TBM Sandy has passed the site.
Work is currently on hold at the Abernethy Road EES while the pre-fabricated panels that will be used for construction of the building are being manufactured.