State Highway 18 (SH 18), also known as the Upper Harbour Motorway, is a

state highway A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either Route number, numbered or maintained by a sub-national state or province. A road numbered ...

that runs between the

Auckland Northern Motorway The Auckland Northern Motorway (known locally as the Northern Motorway, and historically as the Auckland–Warkworth Motorway) in the Auckland Region of New Zealand links Central Auckland and Warkworth in the former Rodney District via th ...

(SH 1) on the North Shore and the Northwestern Motorway (SH 16) in West Auckland, New Zealand. SH 18 forms the northern part of the Western Ring Route, which continues from Waitakere south-east to

Manukau Manukau (), or Manukau Central, is a suburb of South Auckland, New Zealand, centred on the Manukau City Centre business district. It is located 23 kilometres south of the Auckland Central Business District, west of the Southern Motorway, ...

Route

SH 18 begins at the

and runs southwest as a dual carriageway road, and is coextensive with the Upper Harbour Highway, which after two kilometres becomes a

motorway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway, and expressway. Other similar terms ...

at the Albany Highway interchange. This four-lane section of motorway opened in December 2007, and bypassed the single carriageway Upper Harbour Drive. The motorway heads south-west, crossing the upper reaches of the

Waitematā Harbour The Waitematā Harbour is the main access by sea to Auckland, New Zealand. The harbour forms the northern and eastern coasts of the Auckland isthmus and is crossed by the Auckland Harbour Bridge. It is matched on the southern side of the city ...

over the

Upper Harbour Bridge The Upper Harbour Bridge (also called the Greenhithe Bridge) is a motorway bridge in west Auckland, New Zealand. It is technically two bridges, spanning the Upper Waitematā Harbour, and connecting Hobsonville (in West Auckland) and Gree ...

. At Squadron Drive, the highway extends onto a new section of motorway, which opened in August 2011, bypassing Hobsonville Road. This road cuts across in a southwestern direction across farmland to Westgate, where it turns southward and merges with the Northwestern Motorway () southbound.

Interchanges

Former route

SH 18 formerly ran along the Coatesville Riverhead Highway, further north than its current position. This route is now designated as Auckland Urban Route 28.

Cycleway

The route of the new motorway from Upper Harbour Bridge to Westgate was originally to receive a cycleway as well, but although the land was set aside, there is no timetable for the construction of the route.

References

External links