Tonkin Highway Extension and Thomas Road Upgrade

The south-east corridor is an important and fast-growing area. Byford, Armadale, Kelmscott and Gosnells are faced with large volumes of heavy vehicles and other through traffic travelling to and from the South West and Wheatbelt regions.

The extension of Tonkin Highway will reduce traffic pressure and travel time for private and freight traffic, improve road connectivity between current and future residential, business and employment precincts, and improve safety.

The Tonkin Highway Extension project comprises of:

• A 14km extension of Tonkin Highway from Thomas Road to South Western Highway as a four-lane dual carriageway.
• Principal Shared Path (PSP) on the eastern side of the Tonkin Highway extension for the full 14km length, including:
• Connections to Thomas Road, Orton Road, Bishop Road, Mundijong Road and South Western Highway
  • Five underpasses at two grade separation locations (Thomas Road and Bishop Road)
  • Footbridge overpass at Orton Road (east of the highway alignment)
  • Local road connections (Copper Road and Adamson Street)
• Grade separated interchange at Bishop Road
• Roundabouts on Tonkin Highway at Orton Road, Mundijong Road and South Western Highway
• Underpasses at Abernethy Road (road, pedestrian, cyclist and equine), Gossage Road (pedestrian, cyclist and equine) and Shanley Road (road, pedestrian, cyclist and equine)
• Roundabouts at Hopkinson Road/Abernethy Road, and Shanley Road/Jarrahdale Road/South Western Highway
• Bridges over rail at Bishop Road (as part of interchange over the freight rail) and Wright Road (over road and rail)
• Noise and amenity (visual screening) walls
• Lighting for the main roads and the PSP throughout project
• Access and connectivity improvements to local roads including fire and emergency egress where required

The Thomas Road Upgrade project will complement the Tonkin Highway Extension project, and comprises of:

• Widen and duplicate 4.5km of Thomas Road between Kargotich Road and South Western Highway (the section from Thomas Road over Rail to South Western Highway has already been upgraded as part of the METRONET Project).
• Construction of a new grade separated interchange at Thomas Road and Tonkin Highway. This will allow traffic to move freely on Tonkin Highway and provide improved capacity for Thomas Road traffic.
• Construction of 4.5km of new shared path on the south side of Thomas Road.
• Provision of a new signalised equine crossing to connect Byford and Darling Downs bridle paths.
• Local intersection upgrades and changes including:
  • Ballak Place: Left in left out only. Improvement to include left turn deceleration lane
  • Hopkinson Road (north of Thomas Road): Cul de sac
  • Kardan Boulevard: new roundabout
  • Hopkinson Road (south of Thomas Road): Cul de sac
  • Masters Road / Malarkey Road: new roundabout
  • Briggs Road: Left in left out access only
  • Plaistowe Boulevard: New traffic signals to improve access for general traffic and buses
  • Wungong South Road: Reconstruct to an improved priority controlled intersection
• Equine path network north of Thomas Road: realigned to maintain connectivity and accommodate road widening.
• Amenity (visual screening) walls and noise barriers.
• Lighting for the length of Thomas Road upgrades.

Thomas Road will be upgraded to a dual carriageway with two lanes in each direction, and a posted speed of 70km/h.

The Tonkin Highway Extension and Thomas Road Upgrade are being delivered together due to the timing of development and delivery, overlap of stakeholders and geographical location.

 Ongoing engagement

Community and stakeholder engagement activities underway include answering enquiries from local residents, businesses, developers and interested stakeholders, obtaining access to properties for further geotechnical works, and engaging with key stakeholders.

We are working closely with the Shire of Serpentine - Jarrahdale and the Shire’s Equine Advisory Group to understand local issues and opportunities.

 Materials Replacement Strategy

Resource Efficiency is the most significant opportunity in the delivery of major transport projects.

A framework is proposed to maximise the amount of recycled and alternative materials used in project delivery.

A gap analysis and market sounding activities are being undertaken to identify priority areas and materials that are to be targeted across the program, as well as current barriers and opportunities.

Subbase & Basecourse:

• Recovered Road Base Materials
• Crushed Recycled Concrete
• Brick and Tile

Embankment & Subgrade:

• Recovered Sands
• Delitheanated Beta spodumene
• Lithium Aluminate Sand
• Recycled Sand Products

Temporary Works, Minor Structures & Furniture:

• Geopolymer Concrete/ Alkali Activated Binder Concrete
• Super Sulphate Concrete/Low Carbon Concrete
• Recycled Plastic Products

Tonkin Highway Extension

State environmental approvals have been obtained for the Tonkin Highway Extension project under the Environmental Protection Act.

In accordance with Section 95A(3) of the EPBC Act, the Referral document and Preliminary Documentation for the proposed action was available for public comment from 18 June 2021 to 2 July 2021inclusive. No public submissions were received on the Preliminary Documentation.

In accordance with Section 95B(4) of the EPBC Act, a written statement noting that no comments were received, the EPBC referral document and the Preliminary Documentation were made publicly available for information for 10 business days from 23 July, 2021. No submissions were received through the second stage of advertising.

On 17 August 2021, DAWE provided conditional environmental approval for the proposal. Copies of the referral and Preliminary Documentation are available below.

Preliminary Documentation:

• Tonkin Highway Extension Preliminary Documentation - Part 1 (PDF)
• Tonkin Highway Extension Preliminary Documentation - Part 2 (PDF)
• Tonkin Highway Extension Preliminary Documentation - Part 3 (PDF)
• Appendix A - PD Request Further Information Letter signed (PDF)
• Appendix B -Layout Plan (PDF)
• Appendix C - Flora and Vegetation Survey (Woodman 2020) (PDF)
• Appendix D - Black Cockatoo Breeding Habitat Survey (Kirkby 2020) (PDF)
• Appendix E - Black Cockatoo Habitat Quality Assessment (PDF)
• Appendix F - Dieback Assessment (Glevan 2020) (PDF)
• Appendix G - Biological Survey Adequacy and Limitations (PDF)
• Appendix H -The Offset Strategy (PDF)
• Appendix I - Action Management Plan (PDF)
• Appendix J - Tetraria australiensis Fire Management Plan (PDF)

Referral:

• Tonkin Highway Extension Referral 2019-8608 (PDF)
• Tonkin Highway Extension Referral Att 1 - Appendix 1 Proposed Action Location Lot information (PDF)
• Tonkin Highway Extension Referral Att 2 - Figure 1 Site Location (PDF)
• Tonkin Highway Extension Referral Att 3 - Figure 2 Vegetation Association (PDF)
• Tonkin Highway Extension Referral Att 4 - Figure 3 Vegetation Condition (PDF)
• Tonkin Highway Extension Referral Att 5 - Figure 4 Threatened Flora and Ecological Communities (PDF)
• Tonkin Highway Extension Referral Att 6 - Figure 5 Black Cockatoo Trees (PDF)
• Tonkin Highway Extension Referral Att 7 - Figure 6 Black Cockatoo Trees with Hollows (PDF)
• Tonkin Highway Extension Referral Att 8 - Figure 7 Black Cockatoo Foraging Habitat (PDF)
• Tonkin Highway Extension Referral Att 9 - Figure 8 Regional Black Cockatoo Habitat (PDF)
• Tonkin Highway Extension Referral Att 10 - Figure 9 Wetlands and Watercourses (PDF)
• Tonkin Highway Extension Referral Att 11 - Mundijong Road Spring Flora Survey (PDF)
• Tonkin Highway Extension Referral Att 12 - Ministerial Statement 595 (PDF)
• Tonkin Highway Extension Referral Att 13 - Tonkin Hwy Black Cockatoo Assessment (PDF)
• Tonkin Highway Extension Referral Att 14 - Tonkin Highway Extension Reconnaissance Flora Survey (PDF)
• Tonkin Highway Extension Referral Att 15 - Tonkin Highway Extension EIA Final (PDF)

Thomas Road Upgrade

The Thomas Road Clearing Assessment Report can be downloaded here. The purpose of this Report is to provide a report detailing the assessment of the native vegetation clearing that is proposed to be undertaken using the Statewide Clearing Permit (CPS 818) issued to Main Roads.The comments period has now closed.

 Project information

• Project Update - July 2025 - PDF (483 KB)
• Project Update - June 2025 - PDF (508 KB)
• Project Update - March 2025 - PDF (582 KB)
• Frequently Asked Questions - August 2024 - PDF (220 KB)
• Project Update - August 2024 - PDF (449 KB)
• Project Update - April 2024 - PDF (388 KB)
• Project Update -  February 2024 - PDF (471 KB)
• Access and Connectivity Map - PDF (5.09 MB)
• Project Update - June 2023 - PDF (6.38 MB)
• Project Update - September 2022 - PDF (1.29 MB)
• Project Update - January 2021 - PDF (2.04 MB)
• Project Update - October 2020 - PDF (1 MB)
• Project Overview - June 2020 - PDF (2.38 MB)

Fact Sheets

• Environmental Management – June 2025 - PDF (492 KB)
• Managing Construction Impacts – June 2025 - PDF (376 KB)
• Managing Noise – June 2025 - PDF (529 KB)

 Media Statements

• Joint Media Statement - Contract awarded for transformational Tonkin Highway project - 31 January 2025
• Joint Media Statement - Request for proposal issued for Package 2 Of Tonkin Highway Extension and Thomas Road Upgrade - 10 July 2024
• Tonkin Hwy Extension and Thomas Rd Upgrades continue progress - 22 March 2024
• Joint media statement - Expressions of interest called for Tonkin Highway Extension - 27 November 2023
• Industry workshop starts search for Tonkin Highway Extension contractor – 21 January 2021
• Roads budget delivers congestion busting solution and WA jobs - 9 May 2019

 Funding

The $755 million project is jointly funded by the Federal ($604 million) and State ($151 million) Governments. $290 million is also allocated to upgrade Thomas Road, bringing the total funding commitment to $1.045 billion.