State Highway 20 | ||||
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Southwestern Motorway | ||||
Route information | ||||
Maintained by New Zealand Transport Agency | ||||
Length: | 19 km (12 mi) | |||
Existed: | 1977 – present | |||
Major junctions | ||||
South end: | SH 1 Southern Motorway at Manukau City Centre | |||
SH 20B at Puhinui SH 20A at Mangere |
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North end: | Sandringham Road/Maioro Street at Mount Roskill | |||
Highway system | ||||
New Zealand State Highways
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State Highway 20, also known as either the Southwestern Motorway, or the Mangere Motorway, is a New Zealand State Highway linking State Highway 1 at Manukau City Centre with Mount Roskill, via Mangere and Onehunga. Along with its spurs, State Highway 20A and 20B, the state highway serves Auckland Airport, the country's largest, therefore making State Highway 20 a key arterial route connecting the airport to the wider Auckland region and most of the upper North Island. The route also forms the southern part of the future Western Ring Route, a 48 km motorway route bypassing central Auckland.
On the opening of the northbound lanes between SH 1 at Manukau and SH 20B at Puhinui in September 2010, State Highway 20 will become New Zealand's first fully motorway-standard state highway. Currently, northbound traffic between these two points uses local roads.
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SH20 stretches from the Auckland Southern Motorway / New Zealand State Highway 1 in Manukau City to Sandringham Road, Sandringham, in Auckland City - however, currently (mid 2010) only the section between Puhinui Road in the southeast and Sandringham Road in the northwest is of motorway standard. The motorway extension from Queenstown Rd in Mt Roskill to Sandringham Road opened on 15 May 2009.[1]
A large-scale new interchange and 4.5 km length motorway-standard section from SH1 to Puhini Road is being built, and is to be joined by the end of 2010, after a start of works in 2006. The interchange and motorway section includes a total of 12 bridge structures, and is expected to cost approximately $210 million.[2]
The Motorway crosses Manukau Harbour at Mangere Bridge. The bridge duplication, with future provision for rail, was opened 7 months ahead of schedule on 25 July 2010, for a construction cost of $230 million.[2]
The planned final terminus will be the Northwest Motorway / New Zealand State Highway 16 via the Waterview Connection scheduled to open by the middle of the 2010s.
The Southwestern Motorway bypasses Auckland International Airport, with SH20A from the north and SH20B from the east both branching off the SH20 to the airport.
SH20B leaves SH20 at the southern terminus of the Southwestern Motorway and travels west along Puhinui Road to the airport. SH20A leaves the Southwestern Motorway in Mangere and travels south along an additional stretch of motorway, commonly referred to as the "Airport Motorway". The motorway terminates at Kirkbride Road, and traffic continues on SH20A south to the airport.
SH20, SH20A, and SH20B form an almost triangular shape between the southern terminus of the Southwestern Motorway, Auckland International Airport, and the SH20/SH20A motorway junction.
In the 2010s, the Waterview Connection is to connect the current (2011) western end of the motorway from Hillsborough through to New Zealand State Highway 16 at Point Chevalier.
Proposals to upgrade State Highway 20A as part of a general route upgrade to the airport have been floated in a number of studies.
Territorial authority | Location | km | Exit | Destinations | Notes | |
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Current | New (from 1 Nov 2010)[3] | |||||
Manukau City | Auckland — Otara-Papatoetoe/Manurewa Boards | Manukau CBD | 0.0 | SH 1 Southern Motorway south — Hamilton, Tauranga | SH 20 and Southwest Motorway end | |
1 | SH 1 Southern Motorway north — Auckland | |||||
2 | Lambie Drive — Manukau City Centre | |||||
Puhinui | 3 | Route 30 Cavendish Drive | No southbound exit (use Puhinui Road) Northbound entrance and connection to SH 20B and |
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Auckland — Otara-Papatoetoe Board | Puhinui | 3 | SH 20B Puhinui Road — Airport | No northbound exit (use Cavendish Drive) Southbound entrance and connection to SH 20B and |
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Auckland — Mangere-Otahuhu Board | Mangere | 7 | Route 14 Massey Road | |||
9 | SH 20A — Airport | No southbound entrance (use SH20B or Massey Road) Carriageway mainline connects north to west, traffic proceeding from/to south on motorway must 'exit'. |
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10 | Walmsley Road | Southbound | ||||
Coronation Road | Northbound | |||||
Mangere Bridge | 12 | Mahunga Drive — Mangere Bridge Township, Favona | Southbound exit and northbound entrance | |||
Mangere Bridge over Manukau Harbour | ||||||
Auckland City | Auckland — Maungakiekie-Tāmaki Board | Onehunga | ||||
13 | Neilson Street — Onehunga Wharf, Onehunga, Penrose, Mt Wellington | |||||
Auckland — Maungakiekie-Tāmaki/Puketapapa Boards | Hillsborough | 15 | Route 12 Queenstown Road — Auckland City Centre | Northbound exit and southbound entrance | ||
Auckland — Puketapapa Board | 16 | Route 15 Hillsborough Road | ||||
Mount Roskill | 18 | Route 4 Dominion Road | ||||
Sandringham Road/Maioro Street | SH 20 and Southwest Motorway end | |||||
1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus • Closed/Former • Incomplete access • Unopened |
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