Tonkin Highway is a major north–south route that stretches more than 80 km and links growing suburban areas with key industrial precincts, including the Perth Airport Industrial Hub. The Tonkin Highway, south of Roe Highway, is a four-lane divided road with two lanes in each direction and has at-grade intersections.

The proposal includes widening the Tonkin Highway from four to six lanes and grade separation of the highway at Kelvin, Welshpool and Hale Roads, which are the highest priority intersections. This proposal responds to the existing Perth south-east corridor capacity improvements proposal on the Infrastructure Priority List.

The Australian Government has committed $293 million towards the $366 million project.