Tonkin Highway Extension and Thomas Road Upgrade

Tonkin Highway Extension and Thomas Road Upgrade

Tonkin Highway to South Western Highway

Under Construction

Extending Tonkin Highway from Thomas Road to South Western Highway, and upgrading Thomas Road from Kargotich Road to Alexander Road, improving safety, connectivity, and freight efficiency for Perth’s growing south-east corridor.

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What's happening

Current activities across the project include ongoing haulage operations, which will continue day and night until mid-2026. Site preparation works are progressing, including clearing, mulching, topsoil removal and the placement of fill to support future construction. Retaining walls and drainage infrastructure are also being built across the project area, while utility works have commenced, including the relocation of telecommunications, overhead power and Water Corporation services.

Scope

Perth’s south-east corridor, home to fast-growing communities like Byford, Armadale, Kelmscott and Gosnells, is currently impacted by high volumes of heavy vehicles and through-traffic travelling to and from the South West and Wheatbelt regions.

The Tonkin Highway Extension and Thomas Road Upgrade will provide safer, more efficient travel for road users and heavy vehicles, reduce congestion, and improve connectivity between current and future residential, commercial, and employment areas.

These projects are being delivered together due to the timing of development and delivery, overlap of stakeholders and geographical location.

Tonkin Highway Extension

This project involves a new 14 km four-lane dual carriageway between Thomas Road and South Western Highway. It includes:

Principal Shared Path (PSP) along the eastern side of the highway for the full 14 km, with connections to Thomas Road, Orton Road, Bishop Road, Mundijong Road and South Western Highway
Five underpasses and a footbridge at Orton Road for safe crossing by pedestrians, cyclists
Grade-separated interchange at Bishop Road to improve traffic flow and safety
Roundabouts at Orton Road, Mundijong Road and South Western Highway
Underpasses at Abernethy Road and Shanley Road to support vehicle, pedestrian, cyclist, and horse movements
Underpass at Gossage Road to support pedestrian, cyclist and horse movements
Rail bridges at Bishop Road and Wright Road
Noise and visual screening walls, lighting throughout, and improved local road access including emergency egress

The project also caters for recreational needs by supporting the region’s equestrian network with several dedicated horse underpasses and connections.

Thomas Road Upgrade

This upgrade covers the duplication of 4.5 km of Thomas Road between Kargotich Road and South Western Highway, and includes:

A new grade-separated interchange with Tonkin Highway to improve traffic flow
A new 4.5 km shared path on the southern side
A signalised equine crossing connecting Byford and Darling Downs bridle paths
Intersection upgrades, including:

New roundabouts at Kardan Boulevard and Masters Road/Malarkey Road
Left-in/left-out access at Ballak Place and Briggs Road
Cul-de-sacs at Hopkinson Road (north and south of Thomas Road)
New traffic signals at Plaistowe Boulevard
Reconstructed intersection at Wungong South Road

Realignment of the equine path network north of Thomas Road to maintain connectivity

Roadworks

Temporary road closure

Shanley Road

From 12 January to late-2028

To safely construct the new Tonkin Highway Bridge over Shanley Road and to support the delivery of materials to site through the project haulage track, Shanley Road will be temporarily closed between Coogly Road and South Western Highway.

Please click on the map below for more information

Detour map for Shanley Road closure

Travel map

Hopkinson Road, north of Charolais Court to Jersey Road

From mid-February to mid-April 2026

To enable Water Corporation relocation works to occur, Hopkinson Road, north of Charolais Court to Jersey Road, is planned to be temporarily closed to vehicle traffic (subject to approvals). Emergency access will be provided at the end of Jersey Road to Hopkinson Road during the works if required.

Please click on the map below for more information.

Detour map for Hopkinson Road closure

Travel map

Permanent road closure

Hopkinson Road and Thomas Road Intersection

From 15 September 2025

To facilitate the next stage of works and ensure safe vehicle movements, Hopkinson Road south and north of the intersections at Thomas Road have permanently closed.

Please click on the maps below for more information.

Hopkinson Road south of Thomas Road alternate routes

Hopkinson Road north of Thomas Road alternate routes

Hopkinson Road between Cavanagh Close and Gossage Road

From 3 November 2025

As part of the project, the new Tonkin Highway alignment will cross over Hopkinson Road and Gossage Road. To enable these works, Hopkinson Road will be permanently closed to vehicle traffic between south of Cavanagh Close to north of Gossage Road from 3 November 2025. Gossage Road will also become a cul-de-sac at the Hopkinson Road intersection from early November.

Please click on the map below for more information

Alternative routes for Hopkinson Road and Gossage Road

Path and Bridle Trails

Bridle Path closure north of Gossage Road

From late October 2025

To enable construction of the new Tonkin Highway, a section of the existing bridle trail north of Gossage Road, between Bournbrook Avenue and Hopkinson Road will be closed from late-October 2025. A new bridle path connection will be provided via the Gossage Road underpass to Hopkinson Road by late 2028.

Please click on the link below for more information

Bridle Path closure north of Gossage Road

Speed limit reductions

Tonkin Highway

Ongoing to late-2028

Speed limit will be reduced to 60km/h on Tonkin Highway between Rowley Road and Thomas Road.

Thomas Road

Ongoing to late-2028

Speed limit will be reduced to 60 km/h in both directions on Thomas Road between Masters Road and Kargotich Road.

Mundijong Road

Ongoing to late-2028

Speed limit will be reduced to 60 km/h in both directions on Mundijong Road between Kargotich Road and Adonis Street.

South Western Highway

Ongoing to late-2028

Speed limit will be reduced to 60 km/h on South Western Highway between Watkins Road and Transit Road.

Wright Road

Ongoing to late-2028

Speed limit will be reduced to 40 km/h on Wright Road between Bilya Avenue and Watkins Road.

Kargotich Road

Ongoing to late-2028

Speed limit will be reduced to 60 km/h in key locations along Kargotich Road.

Community Engagement

Environment and Heritage

Delivering 14km of new highway and upgrading Thomas Road is a transformational investment in Perth’s south east. It will reduce congestion, improve safety and unlock access to freight routes and employment hubs – supporting METRONET, Westport, and the long-term growth of our WA.

But large-scale infrastructure must also be delivered responsibly.

That is why this project is underpinned by rigorous environmental planning, community engagement and sustainability principles, designed not just to reduce impacts, but to leave a positive legacy.

Responsible Vegetation Clearing and Rehabilitation

To deliver essential infrastructure, some vegetation clearing is required. We know this can raise community concern, and we want to be clear:

Clearing is being minimised wherever possible and carried out in strict accordance with environmental approvals.

The project has obtained approvals under the Environmental Protection Act 1986 and the Environment Protection and Biodiversity Conservation Act 1999, the clearing and construction is subject to the conditions of the approvals.

Key commitments include:

Vegetation will only be cleared where absolutely necessary
All unsealed disturbed areas will be rehabilitated and revegetated using a mix of engineered treatments and planting native species.
Rehabilitation design is underway to maximise opportunities for restoration and biodiversity

Fauna crossings will be installed at waterways to maintain habitat connectivity.

Designing with the Environment in Mind

The project team is actively working to reduce the clearing of native vegetation by realigning roads, protecting trees near work zones where safe, adjusting locations of drainage basins and shared paths.

Flora, Fauna and Heritage Protection

We’ve engaged environmental specialists to assess, monitor and manage impacts on local ecosystems. This includes:

Black Cockatoo habitat hollow inspections
Qualified fauna handlers onsite during clearing to safely relocate fauna

We’re also progressing positive environmental initiatives:

Collaborating with the Kaarakin Black Cockatoo Conservation Centre to provide cleared native vegetation (e.g. banksia cones, eucalyptus branches) to assist in Black Cockatoo rehabilitation.
Grass tree salvage and replanting within the road corridor.

Protecting Aboriginal Heritage

Five Aboriginal Heritage sites are located within the project area. We have received approval under Section 18 of the Aboriginal Heritage Act 1972 to manage these areas respectfully, including salvaging significant items where required and engaging Traditional Owners to monitor ground disturbing activities.

Environmental Working Group

To ensure collaboration and transparency, the project team has established an Environmental Working Group (EWG) with stakeholders including the Shire of Serpentine Jarrahdale.

The EWG helps to:

Share local environmental knowledge
Provide feedback during project design and delivery
Raise environmental concerns and community priorities

We thank all members for their contributions and look forward to continued collaboration.

Driving Sustainability and Innovation

The project is embracing sustainable construction by:

Reusing surplus materials from other infrastructure works
Prioritising the use of replacement and recycled materials where safe and suitable
Reducing waste and conserving resources

Examples being explored include:

Recycled road base, crushed concrete, brick and tile for sub-base and embankments
Recovered sands and innovative materials
Recycled plastic products for temporary works and furniture

All materials undergo laboratory and field testing in line with Main Roads and Australian Standards to ensure safety, quality and performance.

Key Fact:

The project is predicted to deliver $15.2 million in annual vehicle operating cost savings, while reducing emissions through more efficient, and less stop-start travel.

The Tonkin Extension Alliance is currently undertaking market research to identify priority areas for material use and uncover new opportunities for sustainable sourcing.

If your organisation has innovative ideas, materials, or sustainability initiatives that could support this vision, we’d love to hear from you.

Project Publications

Alleviate

pressure on surrounding roads

Reduce

travel times

Improve

road connectivity

Tonkin Highway Extension and Thomas Road Upgrade

What's happening

Temporary road closure

Permanent road closure

Path and Bridle Trails

Speed limit reductions

The Tonkin Extension Alliance is currently undertaking market research to identify priority areas for material use and uncover new opportunities for sustainable sourcing.

If your organisation has innovative ideas, materials, or sustainability initiatives that could support this vision, we’d love to hear from you.

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Funding

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