The four-kilometre alignment that is Transport for NSW’s (TfNSW) Warringah Freeway Upgrade (WFU) project is using an innovative drain application to improve the capture of water runoff and substantially reduce flow widths along the carriageways. This solution, implemented by CPB Contractors as part of a joint venture, enables greater efficiency, sustainability and functionality outcomes.
Spearheading this application is CPB Contractors Design Engineer Afrida Salma, who has played a lead role in the design and implementation of this solution. Through the application of sound engineering principles, Afrida has helped significantly improve project outcomes.
“Traditionally, pit and pipe systems on road infrastructure projects require pits spaced approximately 10 meters apart to capture runoff and achieve optimal drainage flow”, explains Afrida. “In contrast, the slotted drain solution we’re using on the WFU project is almost completely continuous, which will improve water runoff capture and significantly reduce water flow within the carriageways.”
To bring this innovation to life and ensure its effectiveness, Afrida and the WFU team worked closely with TfNSW throughout the process, including the completion of a comprehensive whole-of-life cost assessment, which then guided the strategic placement of each slotted drain. They also oversaw extensive testing and design modifications, taking the product from precast components to in-situ concrete to ensure optimal performance.
From a construction perspective, the slotted drain solution offers notable efficiencies with the installation process requiring less excavation compared to conventional pit and pipe solutions. “The simple reduction of excavation depths has translated to a raft of program benefits. When you decrease the amount of excavation work, you also shorten construction timelines, decrease noise levels, and create less disruption to traffic and surrounding areas”, she explains.
Additionally, the adoption of this slotted drain solution also supports the WFU project’s focus on embracing sustainable construction solutions. “Reduced excavation and construction also means lower energy consumption and a decrease in the use of resources overall” adds Afrida.
CPB Contractors’ joint venture delivery of the Warringah Freeway Upgrade project includes:
- Upgrading four kilometres of the Warringah Freeway between North Sydney and Naremburn
- Improving interchanges with Falcon Street, including a new northbound on ramp at High Street
- Improved public transport links, with a continuous southbound bus lane from Miller Street to the Sydney Harbour Bridge
- Around 2.5 kilometres of new and upgraded cycleways and pedestrian paths, integrated with public transport networks