NorthLink WA was a road construction project in Perth, Western Australia, that saw both the northern section of Tonkin Highway upgraded, and the road extended northwards as the Swan Valley Bypass, to bypass Great Northern Highway. These two component projects were separately funded, with both the state and federal governments contributing to each project. Construction commenced in June 2016 and was completed on 23 April 2020.
Tonkin Highway upgrade
The federal government has allocated $140.6 million to grade-separate Tonkin Highway's intersections with Benara Road, Morley Drive and Collier Road. The funding is part of the five-year phase of the Nation Building Program from 2014–15 to 2018–19. The upgrades are intended to improve freight transportation along the highway. The total cost is expected to be $281.2 million. In the lead up to the 2013 Australian federal election, which resulted in a change a government, the Labor candidate for Perth, Alannah MacTiernan, accused the then-opposition's candidate of lying to the electorate over their commitment to the upgrade. The official policy costings did not contain specific funding for the project. However, an opposition spokesperson claimed it was "in the current forward estimates", and not in the costing, as the upgrade was neither a "new and accelerated" project, nor a project that would definitely not be funded.
Swan Valley Bypass
The proposed Perth Darwin National Highway Swan Valley Bypass is a planned new highway to bypass Great Northern Highway within Perth. From the junction of Reid Highway and Tonkin Highway at Malaga, it will head north towards Ellenbrook, and continue on to Great Northern Highway and Brand Highway in Muchea. The previously planned route of the PDNH, prior to 2012, followed Lord Street, east of Whiteman Park. The state and federal governments have allocated funding to the project, with contracts for the central section awarded to the Great Northern Connect Team on 12 January 2017, and contracts for the northern section awarded to CPB contractors on 30 January 2017. Construction started on the central section on 12 June 2017, and construction on the northern section planned to start late 2017. Construction fully completed on 23 April 2020.
Route
Central section
This section starts at the Reid Highway/Tonkin Highway interchange, which will be upgraded to a cloverstack interchange. Following, to the north, is the Marshall Road flyover, then a two-level roundabout interchange with Hepburn Avenue and Beechboro Road North. Onwards from there is the Baal Street flyover, then at the planned interchange with the Whiteman/Yanchep Highway, the highway veers northeast, meeting up with a partial cloverleaf interchange with Gnangara Road. The highway then follows the edge of Ellenbrook, having a two-level roundabout interchange with The Promenade.
Northern section
This section was originally planned to be a 2 lane single carriageway with at-grade intersections, but because costs went down, it was changed so it can be constructed as a 4 lane dual carriageway with grade separated interchanges. Continuing on from the roundabout interchange with The Promenade in Ellenbrook, it goes north, passing built up areas in Ellenbrook, then going through rural areas. Along the way are roundabout interchanges with Stock Road and Neaves Road, and a flyover over Muchea South Road and the Midland railway line, and the current Brand Highway, before ending at a roundabout interchange with Great Northern Highway and a new Brand Highway.
