The completion of the Tonkin Gap Project marked a significant achievement in improving Perth’s metropolitan road network. Delivered on time and within budget, this project overcame several challenges, including a constrained site, variable ground conditions, high groundwater, and managing traffic through a busy corridor—all during the peak of the COVID-19 pandemic.

The Tonkin Gap Alliance included Main Roads Western Australia, Public Transport Authority, Georgiou, BMD, WA Limestone, GHD, and BG&E.

The $400 million Tonkin Gap and Associated Works Project was part of an infrastructure package announced in 2019. The project is located approximately eight kilometres east of Perth, along Tonkin Highway between Collier Road, Bayswater and Dunreath Drive, Redcliffe.

Connecting the previous major upgrades of Gateway WA and NorthLink WA, this section of Tonkin Highway forms part of a vital freight and commuter access route known as the Perth to Darwin National Highway. The Alliance delivered the Tonkin Gap Project to relieve the bottleneck where the Great Eastern Highway reduced from three lanes to two in Bayswater and Redcliffe, significantly reducing travel time and improving safety.

A package of ‘Associated Works’ to construct rail-enabling works for the METRONET Morley- Ellenbrook Line (MEL) was included in the project. The package included the construction of road and rail bridges and dive structures to enable trains to enter the median strip of Tonkin Highway at Bayswater and then exit in Malaga, approximately eight kilometres to the north.

The scope of works encompassed

• Additional traffic lanes in each direction between Collier Road and Dunreath Drive.
• New bridges over the Swan River, Guildford Road, Railway Parade, the Midland Line railway, and Dunstone Road on the Tonkin Gap section.
• New bridge at Broun Avenue, integrating Morley Station bus interchange, rail bridges at Morley Drive and rail underpass dive structures with integral bridges, at Bayswater and Malaga – on the Associated Works section.
• Upgrades to the Guildford Road and Great Eastern Highway interchanges.
• A principal shared path with bridges, underpasses and local connections for cyclists and pedestrians.
• Pier collision protection and deflection walls to protect seven existing bridges in the Tonkin Highway median.
• Miscellaneous noise walls, retaining walls, lighting, and amenity improvements.

BG&E provided structural and civil engineering, and flood modelling and hydrology services for the project which was completed in late 2023.