Customer: Brisbane Airport Corporation
Location: Brisbane, Queensland
Contract type: Construct
Construction Period: 15 months
The Dryandra Road Works contract is a significant structural element of the New Parallel Runway (NPR) for Brisbane Airport Corporation (BAC).
The Dryandra Road Project is a reinforced concrete 4-lane underpass structure, supported on approximately 700 precast concrete piles including 1.5km of roadway, extensive utilities works, including a full underpass fit out with portions of taxiway and airfield road mounted atop the underpass structure.
Key to Success
The underpass will allow vehicular access either side of the new linking taxiways, which will be constructed as part of the NPR project to connect the new runway in the west to the passenger terminals and existing runway system in the east. McConnell Dowell has included sheet piles in the solution, which results in reduced excavation, better construction access and stability.
Our temporary sheet piling solution is simple and presents the project team and BAC with low risk through reduced marine mud settlement and reduced future taxiway settlement. This, coupled with the installation of precast piles from above the watertable, removes five (5) weeks from the critical program and further risk associated with instability, settlement and inundation.
- Methodology to mitigate risk, and based on well thought out and tried and tested solutions
- Understand documentation required, including Approvals - and set up to deliver this.
- Right team available- right team in the right positions
- 3rd party interfaces, effective access and egresses, services, Telstra, ASA & PUP installation & commissioning and any downtime, causing disruption to Airport Users.
- Very large concerns around windblown sand, line of sight and temporary lighting.
Our construction methodology is safe, simple and minimal risk.
Our sheet piling solution reduces the overall excavation volumes, and will:
- Reduce the underpass excavation by 61%, and result in 66% less backfill quantity.
- Remove the constraint of a linear program as access is possible along both sides of the entire underpass.
- Remove dewatering installation, dewatering draw down, and PASS treatment from the critical path.
- Remove the risk of future settlement of the taxiway as the material adjacent to the underpass remains undisturbed.
- Eliminate stability issues of the open excavation embankments, and reduces susceptibility of the Project to weather events.
- •Allow services along the new alignment as an option, to be installed ahead of the traffic switch to Dryandra Road, removing further program risk.
Our dewatering solution, paired with the sheet piling solution, will deliver:
- 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 is reduced by 69%.
Our precast piling solution of installing piles from above the water table, shown below, will result 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 enhances rig stability and reduces 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 is intercepted by the sheet piles).
By installing precast piles from +4 m AD, earlier commencement of the piling is achieved. Risk to the program is further reduced by working above the water table, on the sand mattress, therefore mitigating any stability issues of the excavation, including and likely heaving of the working platform. Similarly, the Project is not materially affected by wet weather.
Our sheet piling solution will remove the unpredictable activities of dewatering installation, dewatering drawdown and PASS treatment approval being removed from the critical path. The sheet piling also makes the site roads adjacent to the underpass possible, which ensure access along the entire underpass, removing the constraint of a linear project due to access issues. This will result in a flexible program, delinks over 80% of the activities, and allows the ability to accelerate all or parts of the Project if required.
These well considered construction methodologies deliver a flexible program, while making the Project resilient to weather events resulting in surety of program.