Central Motorway Junction
|Central Motorway Junction|
|Auckland CBD, Auckland, New Zealand|
|SH 16 (Northwestern Motorway)|
|Maintained by:||New Zealand Transport Agency|
The Central Motorway Junction or CMJ (best known as Spaghetti Junction and rarely as Central Motorway Intersection), is the intersection of New Zealand State Highways 1 and 16, just south of the central business district of Auckland. A multilevel structure (three traffic levels crossing in several locations), it has been described as a "fiendishly complicated, multi-layered puzzle of concrete, steel and asphalt". Carrying around 200,000 vehicles a day, it is one of the busiest stretches of road in New Zealand. 
The central motorway junction forms the intersection between three major motorways: the Auckland Northern Motorway (SH1), the Auckland Southern Motorway (SH1), and the Northwest Motorway (SH16), and has several off-ramps for access to the city centre. It is mainly in gullies and cuttings around the CBD, and its construction 1960-1970s removed whole neighbourhoods.
It has somewhat of a hybrid function, falling between a typical ‘X’ interchange and ring road around the city centre. All linkages are direct and there is no separate ring road. The interchange and associated structures encircle the Auckland CBD on three sides, the Auckland waterfront to the north forming the fourth 'border' of central Auckland.
Designed in the 1960s and with most of its links built in the 1970s, the CMJ was a major project in a scheme that led to the forcible acquisition and demolition of 15,000 dwellings in the inner suburbs, causing 50,000 people to move away from the area, with major negative effects on the nearby Auckland CBD, and especially the Karangahape Road shopping area, which fell into decline for decades. Two Catholic schools, St Benedict's College (secondary) and St Benedict's School (primary), were forced to closed down.
The CMJ was substantially extended (or in a sense, finally completed) in the 2000s, with the final links opened to traffic in December 2006. During the duration of this NZ$208m project, the existing motorways had to be closed several hundred times during overnight, with traffic rerouted over local roads.
The CCMJ provides motorway-to-motorway links between the following four routes radiating from the city centre:
- Auckland Northern Motorway (SH1) to/from the North Shore via Auckland Harbour Bridge
- Auckland Southern Motorway (SH1) to/from the south
- Northwest Motorway westbound (SH16) to/from the west
- Northwest Motorway eastbound (SH16) to/from Ports of Auckland and eastern suburbs
The last of these links (Northwest Motorway eastbound to Auckland Northern Motorway northbound) officially opened on December 19, 2006, marking the completion of the junction. Plans have now shifted further north, with the tunnel at the Victoria Park Viaduct being the last of a set of three major motorway projects in the area.
The CMJ includes city exits from SH1 and SH16 to downtown, Grafton Gully (the first of the three large motorway projects, containing the section of the Northwest Motorway between the Upper Queen Street bridge and The Strand in Parnell, and the Auckland Southern Motorway between Symonds Street exit and The Strand), with five other pairs of ramps giving access to the central area.
A noteworthy structural component of the CMJ is the area underneath Karangahape Rd, where 19 lanes of traffic forming nine distinct links pass through a cutting through the Karangahape ridge on a multi-level structure.
The other two major motorways under construction in Auckland, the 'South-Western' and 'Upper Harbour' motorways, will form a continuous link in the west of the city, providing an alternative to SH1 between Manukau and Albany. The goal is to provide traffic passing through Auckland, or starting or ending in the western suburbs, with an alternative high-speed route that bypasses the often congested motorways in central Auckland including the CMJ.
The New Zealand Transport Agency was in November 2009 investigating a plan to extend the off-road Northwestern Cycleway through the intersection, to join it to Symonds Street and achieve better cycle linkages from the west into the Auckland CBD. In mid 2010, it became public that a preliminary alignment had been chosen, with the cycle path using the Upper Queen Street bridge to cross the motorway.
- "Harbour Bridge to City Project - Assessment of Environmental Effects". Beca. Transit New Zealand. October 2005. Retrieved 25 February 2010.
- Dearnaley, Mathew (4 December 2006). "Spaghetti Junction comes to the boil". The New Zealand Herald. Retrieved 23 September 2011.
- History - Central Motorway Junction (from the Transit New Zealand 'Central Motorway Improvements' project website. Accessed 2008-06-06.)
- Edward Bennet. "The K'Road area in 1957". Heritage Walk - Karangahape Road (Heritage Guide / Pamphlet). Retrieved 26 June 2011.
- Dearnaley, Mathew (3 November 2009). "$3m project will make life easier for cyclists". The New Zealand Herald. Retrieved 23 September 2011.
- Dearnaley, Mathew (16 April 2010). "Cyclists eager to have last link to city". The New Zealand Herald. Retrieved 6 July 2010.
- Central Motorway Junction (Transit New Zealand's project website)
- CMJ Complete (CMJ entry on Auckland Motorways, a private website)