WA's Biggest Highway Gets $1 Billion Dollars

A major milestone has been reached for one of Western Australia’s largest infrastructure projects, with a $1 billion contract awarded for the Tonkin Highway Extension and Thomas Road Upgrade.

The Tonkin Extension Alliance, a powerhouse consortium made up of BMD, Civcon Civil and Project Management, Georgiou Group, BG&E, and GHD, has secured the contract to deliver the transformative works.

Construction is expected to begin in mid-2025, with project completion anticipated by late 2028.

What’s Included in the Tonkin Highway Extension

The 14-kilometre Tonkin Highway Extension will link Thomas Road to South Western Highway, forming a modern, high-capacity transport route through Perth's south-eastern corridor. The upgrade includes:

A four-lane dual carriageway across the full extension
A Principal Shared Path (PSP) on the eastern side for cyclists and pedestrians
Grade-separated interchanges at key intersections
Five underpasses at two major grade-separated locations
Roundabouts at Orton, Mundijong, and South Western Highway
Overpasses for foot and equine traffic
New bridges over freight rail and road corridors
Noise walls and road lighting for safety and amenity
Improved local road connections and emergency access points

Once complete, Tonkin Highway will support two lanes in each direction with a posted speed of 100km/h.

What’s Planned for Thomas Road

Complementing the highway extension is a $290 million upgrade to Thomas Road, which will see:

Duplication of 4.5km between Kargotich Road and South Western Highway
A new grade-separated interchange with Tonkin Highway
4.5km of new shared path on the southern side
A signalised equine crossing connecting bridle paths
Intersection upgrades including:
- New roundabouts at Kardan Boulevard and Masters Road
- New traffic signals at Plaistowe Boulevard
- Left in/left out restrictions at Ballak Place and Briggs Road
- Cul-de-sacs at Hopkinson Road (north and south)
- Realignment of the local equine path network

Upon completion, the upgraded road will be a dual carriageway with a 70km/h speed limit.

Boost for Freight, Safety, and Local Jobs

The full project aims to remove heavy freight traffic from congested suburban roads, easing pressure for areas such as Byford, Armadale, Kelmscott, and Gosnells. It will also:

Improve freight efficiency and safety
Provide quicker access to major transport routes
Create approximately 4,400 direct and indirect jobs

Government Officials Back the Project

WA Deputy Premier Rita Saffioti said the project would be "a game-changer" for communities in the south.

“This extension complements METRONET’s Byford Rail Extension and other safety improvements in the area, ensuring better access to our transport network for communities in the south,” she said.

Federal Infrastructure Minister Catherine King added:

"This is a major investment that will reduce travel times, ease traffic congestion, and improve safety for all road users."

Federal and State Funding

The $755 million Tonkin Highway Extension is jointly funded by the Australian Government ($604 million) and the Western Australian Government ($151 million). The Thomas Road Upgrade is allocated $290 million, forming a total investment of $1.045 billion.

A Safer, Faster Future for Perth’s South East

This major upgrade reflects Western Australia’s long-term vision to accommodate population growth, reduce road trauma, and enhance freight reliability. As construction gears up in 2025, the Tonkin Highway Extension and Thomas Road Upgrade will pave the way for faster, safer, and more connected travel across the state’s rapidly expanding south-east corridor.