Armadale Rd to North Lake Rd Bridge Project

Armadale Access Alliance

Perth, WA

December 2020  – September 2021

Scope of Work

Dowsing Group was engaged by the Armadale Access Alliance (a consortium comprising Laing O’Rourke and BG&E in partnership with Main Roads) to construct in-situ concrete safety barriers along Kwinana Freeway, Armadale Road, and North Lake Road as part of the Armadale Road to North Lake Road Bridge project.

The project was designed to address heavy congestion at the fifth most congested intersection in Perth by segregating heavy regional traffic from local traffic.

The scope of works included the following:

  • 1.3 km of TL 4 barrier with a 200mm embedment
  • 525 m of TL 4 barrier with a 75mm embedment
  • 308 m of TL5 barrier with a 200mm embedment
  • 298.4 m of TL5 barrier with a 75mm embedment
  • 86.2 m of 1.20m high barrier with a 200mm embedment
  • 94.10 m of 1.42m high barrier with a 200mm embedment


In a Dowsing Group WA first, the use of a dual conveyor on our SP25 Slipform paver was utilised on this project. This innovative configuration uses an additional side feeding conveyor to allow for two concrete trucks to be discharged at once. By implementing an additional conveyor, we were able to increase production in a shorter timeframe, typically 100m3 in a 5-hour window for the shifts it was used for, which achieved time and cost savings across the project.

Additionally, Dowsing used another innovative construction method on the project which saw the slipform team “pour and strip” on the same day for in-situ sections of the barriers. Performed twice on the project to link two sections of slip formed barrier, concrete was poured into the formwork and left to cure for an hour or so before the formwork was stripped, and concrete trowel finished while in a plastic state. Formwork is typically left in position for 48 hours but performing this method increased production time and improved aesthetics due to the seamless transition from extruded to hand poured barrier.

The construction of variable barrier heights in the Armadale Rd dive structure and curved barriers were challenging at times and required set-up adjustments to the slipform machines to navigate the curved sections of barrier while maintaining a smooth profile on the barrier.


View the Main Roads May 2021 video construction update here.