Tonkin Highway

Tonkin Highway is a 44-kilometre-long (27 mi) north-south highway in Perth, Western Australia, linking Perth Airport and Kewdale with the city's north-eastern and south-eastern suburbs. The northern terminus is at Reid Highway in Malaga, and the southern terminus is at Thomas Road in Oakford. It forms the entire length of State Route 4, and connects to several major roads, including Great Eastern Highway, Leach Highway, Roe Highway, and Albany Highway.

Planning for the route began in the 1950s, but the first segment between Wattle Grove and Cloverdale was not opened until 1980. Over the next five years, the highway was extended north to Great Eastern Highway and south to Albany Highway, and a discontinuous section was constructed north of the Swan River. In 1988 the Redcliffe Bridge linked these sections, and three years later, Reid Highway became the northern terminus. The next major works on the highway, between 2003 and 2005, extended the highway south to Thomas Road.

The Gateway WA project plans to improve the road network around Perth Airport, including upgrading the central section of Tonkin Highway to a six-lane freeway-standard road. Construction began in 2013, and completion is scheduled for 2017. Further extensions to both the northern and southern extents of the highway are planned, which would connect the highway to the proposed Perth Darwin National Highway near Ballajura, and to South Western Highway south of Byford.