Tonkin Highway Extension and Thomas Road Upgrade

A section of the Thomas Road Shared Path between Hay Road and Blackberry Ramble will be closed from Thursday 4 June 2026 until May 2027. Path users are encouraged to use the detour route which will be signed along the way (see map in comments). Please note the Armadale Rail PSP will remain open.


The closure is to ensure a safe work environment while we deliver critical infrastructure upgrades along Thomas Road and has been planned in consultation with the Department of Transport and WestCycle.

An exciting milestone has been reached on the project, with the first part of the pedestrian and cyclist underpass structure successfully installed on site.

This is one of seven trapezoid units to form this underpass. The shape improves weight distribution by directing loads from the road above down through the angled walls and into the wider base of the structure. This design also reduces the amount of material required compared to traditional rectangular structures, improving construction efficiency while still delivering a strong and durable outcome for the future road network.

Importantly, installation of this structure is a key step in the overall construction sequencing. It will allow the future Tonkin Highway southbound connection onto Thomas Road to be built, which will play an important role in maintaining vehicle movements through the area during construction of the new Thomas Road bridge over Tonkin Highway.

Great to see another significant piece of infrastructure now in place as progress continues across the project.

Rock pitching works are now underway!

You may notice crews placing rocks onto prepared foundations along embankments and drainage areas across the project. This process, known as rock pitching, creates a strong layer that stabilises the ground and helps protect against erosion.

By slowing and directing stormwater flows, rock pitching also improves drainage performance and helps maintain the shape and integrity of embankments and drains over time, especially during periods of heavy rain.

It’s a durable, low-maintenance solution and a key part of the upgrades to the southern drainage system along Thomas Road.

You may have noticed nightworks underway along Thomas Road, between Masters Road and Plaistowe Boulevard. These works are necessary to support road widening, which will maintain traffic flow as permanent construction continues on the westbound lanes.

These nightworks are expected to continue intermittently from Friday 15 May 2026 to Sunday 7 June 2026. Following completion of the works, the traffic will be switched onto the eastbound lanes. This traffic switch will improve safety for both road users and our workforce by separating live traffic from active construction zones, allowing works to continue more efficiently and with reduced risk.

To support construction of the new Mundijong Road and Tonkin Highway intersection, Mundijong Road is proposed to be temporarily closed between Pure Steel Lane and Adonis Street from June 2026 to December 2026.

This temporary closure will allow Mundijong Road to be aligned to meet the Tonkin Highway intersection, provide a safe, protected work zone, and minimise interaction between traffic and the worksite.

In addition, the Lampiter Drive and Mundijong Road intersection will be permanently closed, with emergency egress maintained at the end of Lampiter Drive.

What to expect:
• Pure Steel Lane and Adonis Street will remain open during these works
• Signed detour route through Bishop Road (see map in comments)

The project is working closely with the Shire of Serpentine Jarrahdale and the Department of Fire and Emergency Services (DFES) to ensure emergency access routes are maintained during construction and are incorporated into the final road design. Bushfire safety and emergency response are key considerations in the planning process.

Public submissions on this planned closure are now open and can be made in writing to the Shire of Serpentine Jarrahdale by 5pm, 3 June 2026.

Submissions should be addressed to:

Chief Executive Officer
Shire of Serpentine Jarrahdale
6 Paterson Street, Mundijong WA 6123
Email: [email protected]

https://www.sjshire.wa.gov.au/publicnotices/tonkin-highway-extension-and-thomas-road-upgrade-proposed-temporary-road-closure-mundijong-road-between-pure-steel-lane-and-adonis-street/10195

We recently had the opportunity to meet with students at Byford Secondary College.

We visited a Year 12 Mathematics class to talk about the wide range of careers in construction, and how maths is used every day in delivering major infrastructure projects like ours, from planning and design through to construction on site.

It was great to hear such thoughtful and interesting questions from the students, and to discuss how the skills they’re developing in the classroom are applied in real world project delivery.

We really value opportunities like this to support local students and help them explore future career pathways in the construction industry.

Thank you to everyone who provided feedback on the recent Public Notice issued by the Shire of Serpentine Jarrahdale regarding the planned closure of Orton Road. In response, we’ve reviewed the proposed staging of works and identified an opportunity to delay the start of these works. The planned closure will now be from mid-June 2026 to September 2026.

These works may slightly overlap with Water Corporation’s bridge upgrade on Gossage Road, depending on construction progress.

This closure will enable our team to construct the new Orton Road connection to Timbrel Road (formerly Hopkinson Road), while maintaining a safe, protected work zone and minimising interaction between traffic and the worksite. This connection will also support future stages of work as we continue construction of the new Tonkin Highway and Orton Road intersection.

What to expect:
• Bullock Drive and Timbrel Road will remain open
• Local access to properties on Orton Road will be maintained
• Properties east of the closure will be accessed via Timbrel Road
• Properties west of the closure will be accessed via Orton Road from Kargotich Road (see map in comments)

We are working closely with the Shire of Serpentine Jarrahdale and the Department of Fire and Emergency Services (DFES) to ensure emergency access routes are maintained throughout construction and considered in the final road design. Bushfire safety and emergency response remain key priorities in our planning.

The first underpass slab has officially been poured at the future Thomas Road and Tonkin Highway Interchange, a major step forward in bringing this intersection to life. This is the first of five underpasses at this interchange, which will support active transport movements throughout the area.

A significant sustainability achievement, by adopting a continuous pour slab, the project team has streamlined construction and reduced the volume of materials needed across six underpasses on the project.

This includes:
• Over 7,200m³ less material below the underpasses (equivalent of three Olympic sized swimming pools)
• 375m³ less concrete used (equivalent of 90 household driveways)
• 47 tonnes of reinforcement saved (equivalent of 30 cars)
• 600 tonnes of basecourse material (equivalent of 30 fully loaded dump trucks)

This is sustainability in action, reducing material use, cutting down on transport requirements and emissions, and building smarter for the future.

During May 2026, the first precast underpass units will be installed, enabling backfill to commence. This will pave the way for permanent construction of the slip lane from Tonkin Highway (southbound) onto Thomas Road (eastbound), supporting traffic movements during future stages of work.

Big things are happening on site!

Find out what key activities are currently underway and see the progress being made.

Click below to check out the latest Construction Update 👇
https://www.mainroads.wa.gov.au/497419/globalassets/projects-initiatives/projects/metro/tonkin-hwy-ext-thomas-rd-upgrade/thetru-project-update-april-2026.pdf

Thank you for your feedback to the recent public notice, issued by the Shire of Serpentine Jarrahdale, relating to the temporary closure of Timbrel Road (formerly Hopkinson Road), north of Abernethy Road to Devon Court. All submissions have been carefully reviewed and, where possible, incorporated into the traffic management arrangements for the area.

From Monday, 20 April 2026 until October 2026, this section of Timbrel Road will be temporarily closed. This closure is essential to maintain safety for road users and our workforce as we undertake service relocation works, drainage upgrades, foundation preparation for the Tonkin Highway bridge over Abernethy Road and permanent construction of the Abernethy Road and Timbrel Road roundabout.

The project is working closely with the Shire of Serpentine Jarrahdale and the Department of Fire and Emergency Services (DFES) to ensure emergency access routes are available during construction (map in comments).

We understand that road closures can be frustrating, and we thank you for understanding.