The $175 million NorthLink Western Australia (WA) Stage 3 project involves the design and construction of approximately 26 kilometres of new dual carriageway highway between Ellenbrook and Muchea, in the North East of Perth.

This project is the third stage of the overall $1.12 billion NorthLink WA project, which also included upgrades to the Tonkin Highway to complete a free flowing state-of-the-art transport link connecting Great Northern Highway and regional areas, with Malaga, Kewdale and Perth Airport.

In partnership with CPB Contractors, BG&E is the Lead Consultant to deliver the design and construction of the NorthLink Stage 3 project.

The key features of this mega infrastructure project comprise:

• a 26-kilometre freeway, standard dual carriageway highway, fully grade separated;
• three grade separated roundabout interchanges, each with two bridges to carry the highway over the roundabouts below;
• two bridges over railways and local roads;
• two bridge over waterways;
• a four-metre wide principal shared path extending the full length of the highway;
• a pedestrian underpass and a pedestrian bridge; and
• more than 100 culverts, which require flood modelling to design and optimise.

Some of the elements of BG&E’s structural design include:

• an innovative continuous bridge design at the two railway crossings, with precast TeeRoff beams that were made using a simple post-tensioned stressbar joint over the piers;
• adoption of smaller ‘winged-plank’ precast girders to allow for an improved span-to-depth ratio and easy installation (of the small units);
• full precast concrete barrier panels, attached to the bridge deck with a small stitch joint; and
• six variable message sign units.

BG&E is also coordinating the other design services including electrical, geotechnical, pavements and landscaping, as well as represented the design team during the community and stakeholder engagement process.