State Highway 18 (New Zealand)

State Highway 18 shield}}
State Highway 18
Map
Route information
Maintained by NZ Transport Agency
Length14 km (8.7 mi)
Major junctions
North-east end SH 1 (Auckland Northern Motorway) at North Shore
South-west end SH 16 south (Northwestern Motorway) at West Harbour
Location
CountryNew Zealand
Primary
destinations		Greenhithe, Hobsonville
Highway system
← SH 17→ SH 20
The former route of State Highway 18, in 2010, was a mostly rural highway. This route is now designated Urban route 32.
The Hobsonville section of the Upper Harbour Motorway, looking west from the Trig Road Interchange

State Highway 18 (SH 18), also known as the Upper Harbour Motorway, is a state highway that runs between the Auckland Northern Motorway (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.