Auckland Southern Motorway

The Auckland Southern Motorway (also known as the Southern Motorway, and historically as the Auckland–Hamilton Motorway) is the major route south out of the Auckland Region of New Zealand. It is part of State Highway 1.

The motorway is 45 kilometres in length, with 28 junctions including termini. It runs from the Central Motorway Junction in central Auckland, through Manukau City, Papakura, and Drury, before terminating onto the Waikato Expressway at the top of the Bombay Hills.

The Southern Motorway starts just north of the Central Motorway Junction (Spaghetti Junction) on the west side of central Auckland. The motorway is a direct extension of the Northern Motorway, which changes to the Southern Motorway just south of exits 424C and 424D.

For the first kilometre, the road is two lanes each way due to the constraints of the Victoria Park Viaduct to the north. The motorway then delves deep into the Central Motorway Junction, turning eastward to form a southern boundary to the Auckland CBD, then turns south-eastwards as it leaves the junction. There are several exits northbound only through the junction, connecting to the city centre and the Northwest Motorway.

South of the junction is the busiest section of the motorway, and busiest section of road in New Zealand carrying an average of 200,000 vehicles per day, and to cope with this, the short section between Khyber Pass Road and Gillies Avenue is five lanes wide each way. A large volume of traffic leaves at Gillies Ave to head for Auckland International Airport.

The motorway then crosses the narrow Newmarket Viaduct, before turning to follow the North Auckland Rail Line to Ellerslie. At Ellerslie, the motorway leaves the railway line and skirts around Penrose, heading in a south-easterly direction towards Hamlins Hill where there are junctions with the South-Eastern Highway (Southbound exit and northbound entrance only) and the Mt Wellington Highway.

Immediately after the Mt Wellington Highway interchange, the motorway curves south to head towards the Tāmaki River. After crossing the Tāmaki River, the motorway forms a boundary between the suburbs of Papatoetoe to the west and Ōtara to the east. At Manukau City Centre, the motorway has a major junction with the South-Western Motorway and then bypasses Manurewa to the east. The motorway then curves towards the south-westerly direction where it crosses Great South Road at the Takanini interchange. The motorway once again curves south and bypasses Papakura to the west.

At Drury, the motorway has a junction with State Highway 22, before heading south towards the Bombay Hills. At the Bombay interchange, the motorway becomes the Waikato Expressway and continues on south towards the Waikato.