The $175 million NorthLink WA: Stage Three project involved the design and construction of 26 kilometres of new dual carriageway highway between Ellenbrook and Muchea, in the North East of Perth.

This project was the third component of the overall $1.12 billion NorthLink WA project, WA’s largest ever road initiative that now services regional traffic movements to areas such as Kewdale, Malaga, Perth Airport, and the CBD.

In partnership with CPB Contractors, BG&E was the lead consultant to deliver the design and construction of Stage Three.

The key features of this mega infrastructure project comprised

• 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 and two bridges over waterways.
• A four metre wide principal shared path extending the highway length.
• A pedestrian underpass and a pedestrian bridge.
• More than 100 culverts that required flood modelling to design and optimise.

BG&E provided structural and civil engineering services.

Some of the key elements of BG&E’s structural design included

• An innovative continuous bridge design at the two railway crossings, with precast Tee- Roff beams that were made using a simple post-tensioned stress bar 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.
• Six variable message sign units.

BG&E also coordinated the other design services including electrical, geotechnical, pavements and landscaping – and represented the design team during the community and stakeholder engagement process.