Work is now underway on a “once-in-a-generation” road infrastructure project designed to unlock access to one of Western Australia’s fastest-growing regions.

The $1-billion Tonkin Highway Extension and Thomas Road Upgrade will deliver a new 14-kilometre highway connection and significantly expand capacity in Perth’s south-east corridor, with completion targeted for late 2028.

Early works, including site establishment and traffic realignments, have commenced, marking the transition into full-scale construction.

Key Points

• $1bn+ Tonkin Highway Extension and Thomas Road Upgrade now under construction.
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• 14km extension from Thomas Road to South Western Highway and duplication of 4.5km of Thomas Road.
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• Expected to carry more than 60,000 vehicles per day once complete.
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• Completion scheduled for late 2028.
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• Jointly funded by the Australian and WA governments, with $749m from the Commonwealth.
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• Estimated 4,400 direct and indirect jobs to be created.

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Project Significance

The Tonkin Highway project is being positioned as a critical enabler of growth in Perth’s south-east. Rapid population expansion in suburbs such as Byford, Armadale and Gosnells has placed sustained pressure on local roads, freight routes and commuter travel times.

By extending the Tonkin Highway and removing heavy vehicles from suburban streets, the project aims to improve safety, reduce congestion and strengthen freight efficiency across a corridor that links Perth Airport, intermodal freight facilities at Kewdale, and key industrial precincts.

For government, the project represents a shift toward long-term network planning – building high-capacity infrastructure ahead of demand, rather than reacting after congestion becomes entrenched.

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Further Details: Capacity, Connectivity and Community Impact

The project includes a series of grade-separated interchanges, underpasses and roundabouts designed to improve traffic flow and reduce accident risk. Shared paths for cyclists and pedestrians will be delivered along the corridor, alongside equine crossings developed in consultation with local users.

Once complete, the road upgrade will complement the METRONET Byford Rail Extension, creating more balanced transport options across the region and reducing reliance on a single mode of travel.

Beyond transport outcomes, the project is also expected to deliver a significant economic boost, supporting thousands of jobs and creating opportunities for local suppliers, contractors and First Nations businesses.

While construction will inevitably bring short-term disruption, the scale of the investment reflects the government’s view that Perth’s south-east can no longer rely on incremental upgrades. Instead, the Tonkin Highway Extension is intended as a foundational piece of infrastructure – one designed to support growth, freight and mobility for decades to come.