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 the Hibiscus Coast and North Shore. It is part of State Highway 1.

It is 58 kilometres (36 mi) in length, with 17 junctions. Until the end of the 1980s, it was largely associated with the Auckland Harbour Bridge as a connection between central Auckland and the North Shore, but since 1994 it has been extended to Warkworth to become the primary route between the Auckland urban area, the Hibiscus Coast satellite towns, the northern Rodney district, and Northland. Between the 1959 opening of the motorway and 1984, tolls were collected on the Auckland Harbour Bridge, and since 2009 tolls have been collected on the Northern Gateway Toll Road.

In 2019, 170,000 vehicles per day were crossing the Harbour Bridge section of the motorway.

The Northern Motorway starts near Puhoi, in the former Rodney District, at the southern end of the Puhoi-Warkworth Motorway, which opened in 2023.

The initial 7 km section is an automated-toll road, also known as the Northern Gateway Toll Road. It begins by travelling under Johnstone's Hill though 340-metre long twin tunnels. The electronic toll-registering gantry is at the southern end. At the first junction, west of Orewa, the motorway becomes toll free.

The next 17 km to Albany runs through a mainly rural environment. An interchange at Silverdale provides access to the Hibiscus Coast and the Whangaparāoa Peninsula, and access to the alternative toll-free route north via Urban Route 31 (formerly State Highway 17). The Orewa interchange can also be used, but requires driving through local residential areas. South of the junction at Dairy Flat is the motorway's only service centre, which serves northbound traffic, and is the toll cash-payment point for northbound traffic.

The motorway then descends steeply into the northern suburbs of the former North Shore City, the northern of Auckland's four former cities. Crawler lanes are provided for heavy vehicles between Oteha Valley Road and Greville Road. The Greville Road interchange was until 1999 the northern terminus, with the current northbound entrance and exit ramps following the old formation down to the roundabout intersection with Albany Highway.

The motorway proceeds south-east through the suburbs of the North Shore, with interchanges at Constellation Drive, Tristram Avenue, Northcote Road and Esmonde Road allowing access to the suburbs. The Constellation Drive interchange is the northern terminus of the Western Ring Route, which provides an alternative north–south motorway route around Auckland via the Upper Harbour Motorway and the Northwestern Motorway.