Altus Traffic Perth Crew - Traffic Management on the Stephenson Avenue Extension
Location: Mitchell Freeway corridor, Stirling, Perth, Western Australia
Client: S2M Evolution Alliance (Acciona, Clough and WSP), delivering the project for Main Roads Western Australia
Dates: Altus Traffic has been on site providing traffic management of the highways since early 2022 and remains on the project today, with completion expected late 2026.
Altus Traffic's Perth crew is running traffic management for the Stephenson Avenue Extension, one of the largest interchange projects on Perth's freeway network. On closure nights, that means up to 13 Traffic Controllers, 2 cone trucks and 3 Truck Mounted Attenuators (TMAs) working a single carriageway direction, doubling in scale whenever both the northbound and southbound Mitchell Freeway carriageways close at the same time.
What Is the Stephenson Avenue Extension Project?
The Stephenson Avenue Extension is a Main Roads Western Australia project building a new connection from Cedric Street to Scarborough Beach Road through Stirling, with a new grade-separated interchange at Mitchell Freeway. The current stage, Phase 2, is jointly funded by the Australian and Western Australian Governments and includes a bridge over Mitchell Freeway and the Joondalup rail line, a new link from Sarich Court to Cedric Street, shared paths and an underpass either side of the freeway, and an upgrade to the Stirling Bus Interchange, expanding it from 18 to 29 bus stands. The Stephenson Avenue Interchange opened to traffic in December 2025, with finishing works continuing through 2026 (Main Roads WA).
Who Is Altus Traffic Working with on This Project?
Altus Traffic's client on the Stephenson Avenue Extension is the S2M Evolution Alliance, the delivery alliance of Acciona, Clough and WSP contracted to build Phase 2 for Main Roads WA. Our Perth crew provides the on-road traffic management that allows the alliance to safely close sections of Mitchell Freeway and carry out construction work beneath and beside live traffic.
How Long Has the Altus Traffic Perth Crew Been on the Stephenson Avenue Extension?
Construction on the Stephenson Avenue Extension began in early 2022. Altus Traffic's Perth crew joined partway through the project, taking over traffic management from the previous provider, and has remained on site continuously since. Completion is scheduled for late 2026 and Altus Traffic will remain on the job through to that handover.
How Many Crew and Vehicles Does Altus Traffic Deploy on Site?
Resourcing on the Stephenson Avenue Extension scales to match how many carriageways are closing on a given night.
13 Traffic Controllers per direction, southbound or northbound
2 cone trucks per direction
3 Truck Mounted Attenuators (TMAs) and drivers per direction
Scaling Up for Dual-Carriageway Closures
When both the southbound and northbound carriageways of Mitchell Freeway need to close at the same time, Altus Traffic doubles those numbers, deploying 26 Traffic Controllers, 4 cone trucks and 6 TMAs across the site in a single night. That scaling keeps the same safety margins in place on both carriageways at once, rather than stretching one crew across two live work fronts.
Keeping People Safe on a Live Freeway
Every one of those closures puts Traffic Controllers next to a freeway carrying traffic at highway speed just metres away. Scaling crew and vehicle numbers to match the closure, rather than running the same headcount regardless of scope, is what keeps that margin consistent night after night. Most importantly, it means our crew, and every motorist moving through the Stephenson Avenue interchange gets home safely.
Traffic Management Services from Altus Traffic WA
Altus Traffic is Australia's largest traffic services provider, supporting over 1,800 organisations with more than 6.2 million service hours and 50,000 traffic plans and permits every year, across roads, rail, utilities, events and government projects nationwide. In Western Australia, our Perth crew delivers traffic management for major infrastructure projects like the Stephenson Avenue Extension, working directly with principal contractors and alliances to plan, resource and run safe road closures from single-lane restrictions through to full freeway shutdowns.
For more information or to discuss a project or quote with Altus Traffic Western Australia, get in touch with our WA team.