State Highway 16
Twin Coast Discovery Highway
SH16 viewed from the Te Atatu Road overbridge during New Zealand's COVID-19 lockdown
Route information
Maintained by NZ Transport Agency
Length	108 km (67 mi)
Tourist routes	Twin Coast Discovery Highway
Major junctions
Southeast end	Port of Auckland
Major intersections	SH 1 south (Auckland Southern Motorway) at Central Motorway Junction SH 1 north (Auckland Northern Motorway) at Central Motorway Junction SH 20 (Southwestern Motorway) at Waterview SH 18 (Upper Harbour Motorway) at West Harbour
Northwest end	SH 1 (Rodney Street) at Wellsford
Location
Country	New Zealand
Primary destinations	Auckland, Helensville, Wellsford
Highway system
New Zealand state highways Motorways and expressways List
← SH 15 → SH 17

State Highway 16 (SH 16) is a New Zealand state highway linking central Auckland with Wellsford, via Auckland's Northwestern Motorway, Helensville and Kaukapakapa. It provides an alternative to SH 1 for traffic travelling between Auckland and parts of Northland from Wellsford northwards.

Within the Auckland metropolitan area, SH 16 mostly runs along the Northwestern Motorway, the major exception being the first 2 km between the Port of Auckland and the Central Motorway Junction. Outside the Auckland metropolitan area, SH 16 is a single carriageway with at-grade intersections.

Route

SH 16 begins in Central Auckland at the corner of The Strand, Tamaki Drive and Quay Street, directly opposite the Port of Auckland. It travels south via The Strand where it reaches the lights at Beach Road and Parnell Rise where it changes to Stanley Street. After one more set of lights at Alten Road, SH 16 becomes coextensive with the Auckland Northwestern Motorway. The highway travels through the Central Motorway Junction where there are exits to SH 1 both northbound and southbound. It then runs west and forms a junction with SH 20 and then continues to West Auckland over a causeway crossing Traherne Island and the Whau Estuary. SH 16 then passes through West Auckland and past the junction with SH 18 (Upper Harbour Motorway) where it can be accessed by northbound traffic. The Northwestern Motorway terminates at a roundabout with Brigham Creek Road and Fred Taylor Drive. From here SH 16 reverts to single carriage road. It passes through the communities of Kumeū, Huapai, Waimauku and Helensville, eventually reaching the west coast. From there on SH 16 skirts the Kaipara Harbour along the Kaipara Coast Highway, eventually bearing northeast to meet SH 1 at Wellsford, where it terminates.^{[1][unreliable source?][when?]}

Route changes

SH 16 north of Helensville to Wellsford was temporarily revoked in 1994. It was reinstated in 1997.^[2][3]

Major intersections

Refer to Northwestern Motorway for a complete list of motorway intersections

Territorial authority	Location	km	jct	Destinations	Notes
Auckland Council	Port of Auckland	0		Quay Street/Tamaki Drive	SH 16 begins
	Parnell	1		Parnell Rise Beach Road
				Nicholls Lane Alten Road	SH 16 becomes Northwestern Motorway
	Auckland CBD	2		SH 1 south (Auckland Southern Motorway)/Thermal Explorer Highway – Manukau, Hamilton	Westbound exit and eastbound entrance
		3		SH 1 north (Auckland Northern Motorway)/Twin Coast Discovery Highway – North Shore, Whangarei	Westbound exit and eastbound entrance
		4		SH 1 south (Auckland Southern Motorway)/Thermal Explorer Highway – Manukau, Hamilton	Eastbound exit and westbound entrance
				SH 1 north (Auckland Northern Motorway)/Twin Coast Discovery Highway – North Shore, Whangarei	Eastbound exit and westbound entrance SH 16/Twin Coast Discovery Highway concurrency begins
	Waterview	8		SH 20 south (Southwestern Motorway)	Waterview Connection
	Westgate	19		SH 18 east (Upper Harbour Motorway) – North Shore	Northbound exit and southbound entrance
	Whenuapai	22		Fred Taylor Drive Brigham Creek Road (and )	Northwestern Motorway ends
	Kumeū	23		Coatesville-Riverhead Highway (Regional Route 28) – Riverhead, Albany	Former route for SH 18
	Helensville	48		Parkhurst Road – Parakai, South Kaipara Head
	Wellsford	108		SH 1 north (Rodney Street)/Twin Coast Discovery Hwy North – Whangarei, Kaitaia SH 1 south (Rodney Street)/Thermal Explorer Highway South – Warkworth, Auckland	SH 16 ends