# State Highway 18 (New Zealand)

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.

## Route

SH 18 begins at the Auckland Northern Motorway and runs southwest as a dual carriageway road, and is coextensive with the Upper Harbour Highway, which after two kilometres becomes a motorway 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 over the Upper Harbour Bridge. 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 (SH 16) southbound.

## Interchanges

| Territorial authority | Location | km | mi | Exit | Destinations | Notes |
| Auckland – Upper Harbour Local Board | Unsworth Heights | 0.0 | 0.0 | | SH 1 south (Northern Motorway) – Auckland | SH 18 and Upper Harbour Motorway begins |
| Auckland – Upper Harbour Local Board | Unsworth Heights | | | | SH 1 north (Northern Motorway) – Whangarei | |
| Auckland – Upper Harbour Local Board | Unsworth Heights | 0.5 | 0.31 | 1 | Caribbean Drive Paul Matthews Road | Eastbound exit and westbound entrance |
| Auckland – Upper Harbour Local Board | Unsworth Heights | 2.4 | 1.5 | 2 | Route 26 (Albany Highway) | |
| Auckland – Upper Harbour Local Board | Greenhithe | 4.3 | 2.7 | 4 | Greenhithe Road | Westbound exit and eastbound entrance |
| Auckland – Upper Harbour Local Board | Greenhithe | 6.2 | 3.9 | 6 | Tauhinu Road | Eastbound exit and Westbound entrance |
| Auckland – Upper Harbour Local Board | Greenhithe | 7.4 | 4.6 | Upper Harbour Bridge (Waitematā Harbour) | Upper Harbour Bridge (Waitematā Harbour) | Upper Harbour Bridge (Waitematā Harbour) |
| Auckland – Upper Harbour Local Board | Hobsonville | 8.8 | 5.5 | 8 | Squadron Drive | Westbound exit and eastbound entrance |
| Auckland – Upper Harbour Local Board | Hobsonville | 10.7 | 6.6 | 9 | Brigham Creek Road – Whenuapai, Wellsford | to SH 16 north |
| Auckland – Upper Harbour Local Board | Hobsonville | 12.7 | 7.9 | 10 | Trig Road | Westbound exit and eastbound entrance |
| Auckland – Henderson-Massey Local Board | Westgate | 13.9 | 8.6 | 11 | Route 32 (Hobsonville Road) | Westbound exit and eastbound entrance |
| Auckland – Henderson-Massey Local Board | Westgate | 14.0 | 8.7 | | SH 16 south (Northwestern Motorway) – Waitakere, Auckland | SH 18 and Upper Harbour Motorway ends |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Incomplete access |||||||

## 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.