State Highway 18 (New Zealand)

State Highway 18
Route information
Maintained by NZ Transport Agency
Length	14 km (8.7 mi)
Major junctions
From	SH 1 Northern Motorway, Meadowood, North Shore City
To	SH 16 Northwest Motorway, West Harbour, Waitakere City
Location
Country	New Zealand
Primary destinations	Greenhithe, Hobsonville
Highway system
New Zealand state highways Motorways and expressways List
← SH 17 → SH 20

Early 2010. Existing State Highway 18 as a standard, mostly rural, highway.

The Hobsonville section of the Upper Harbour Motorway, looking west from the Trig Road Interchange

State Highway 18 (also known as the Upper Harbour Motorway) is a State Highway linking North Shore City and Waitakere City in Auckland, New Zealand. It is the northern part of the Western Ring Route. State Highway 18 formerly ran along the Coatesville Riverhead Highway, further north than its current position.

Route

State Highway 18 begins at the Northern Motorway, as a dual carriageway road, heading west on Upper Harbour Highway, after two kilometres becoming 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 Waitemata 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 cut 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	#	Destinations	Notes
Auckland - Upper Harbour Board		0.0		SH 1 Northern Motorway (south) – Auckland	SH 18 ends
				SH 1 Northern Motorway (north) – Whangarei
				Caribbean Drive
				Paul Matthews Drive
				Unsworth Drive	Westbound exit only
		2.4	2	Route 29 Albany Highway	Motorway ends
	Greenhithe	4.3	4	Greenhithe Road	Eastbound exit and westbound entrance
		6.2	6	Tauhinu Road	Westbound exit and eastbound entrance
		7.4		Upper Harbour Bridge over Waitemata Harbour
	Hobsonville		8	Squadron Drive	Westbound exit and eastbound entrance
			9	Brigham Creek Road – Whenuapai, Helensville	to north
			10	Trig Road	Westbound exit and eastbound entrance
Auckland – Henderson-Massey Board	Westgate		11	Route 32 Hobsonville Road	Westbound exit and eastbound entrance
				SH 16 Northwest Motorway (south) – Waitakere, Auckland	SH 18 ends
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

See also

• List of New Zealand State Highways