Customer: Brisbane Airport Corporation
Contract type: Construct Only
Location: Brisbane, Queensland
The Dryandra Road Works contract was a significant component of the New Parallel Runway (NPR) project for Brisbane Airport Corporation (BAC).
The Project involved construction of a 1.5 km long, four-lane reinforced concrete underpass structure, supported on approximately 700 precast concrete piles. The underpass allows vehicular access either side of the new linking taxiways, which were constructed as part of the NPR project.
McConnell Dowell's scope of work included full underpass fit out, with portions of taxiway and airfield road mounted atop the underpass structure. Our construction methodology included a number of innovations aimed at safety, simplicity and minimising risk.
Our sheet piling solution:
- Reduced the underpass excavation by 61%, and resulted in 66% less backfill quantity.
- Removed the constraint of a linear program by making access possible along both sides of the entire underpass.
- Removed dewatering installation, dewatering draw down, and PASS treatment from the critical path.
- Removed the risk of future settlement of the taxiway as the material adjacent to the underpass remained undisturbed.
- Eliminated stability issues of the open excavation embankments, and reduces susceptibility of the Project to weather events.
- Allowed services along the new alignment to be installed ahead of the traffic switch to Dryandra Road, removing further program risk.
Our dewatering solution, paired with the sheet piling solution, delivered:
- Reduced duration and removal of this activity from the critical path
- Reduced cost by reducing the number of dewatering wells
- Reduced dewatering volume by a third to 2.5 ML /day as the area being dewatering was reduced by 69%.
Our precast piling solution of installing piles from above the water table, resulted in:
- Earlier and unimpeded access for the piling rigs to install precast piles
- Effective and efficient delivery of piles directly to the piling rigs
- A smaller piling platform that enhanced rig stability and reduced heaving risk from the marine muds
- Reduced piling vibrations thus reducing the risk of destabilising the excavation sides
- Reduced excavation area by 69% removing the risk of excavation impoundment
- Reduced impact of weather events due to surface water ingress (which were intercepted by the sheet piles).
These well considered construction methodologies enhanced access during construction, reduced costs and delivered program surety and flexibility by making the project resilient to weather events.