About this Project

Key Facts

  • Four-lane motorway with provision for another lane to be added to each side in the future (giving six lanes in total)
  • 4.5km in length
  • Three interchanges with motorway-to-motorway connections to SH20 and SH1 at Manukau City
  • Twelve bridges (and one temporary bridge)
  • 268,000 m2 of pavement
  • 140 ha site area
  • 920,000 m3 of earthworks
  • 7 sedimentation ponds
  • 16.8 km of drainage
  • Estimated cost - $210m
  • Construction commenced in June 2006
  • Construction completed by December 2010

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Key Features

The new motorway link is made up of two lanes in each direction. The design also allows for a third lane to be added to each side in the future, giving six lanes in total.

Within this section of motorway, two grade separated interchanges at Cavendish Drive and Lambie Drive are included - as well as motorway-to-motorway connections to SH20 and SH1 at Manukau City.

The work includes five motorway crossings over local roads and streams, as well as the main North Island rail line.

Cavendish Drive Interchange

  • Formerly referred to as Nesdale Avenue Interchange
  • Extended to pass under the new motorway and across a diversion of the Puhinui Stream - to join the existing SH20 at Roscommon Road
  • Major entry and exit point for traffic coming to and from the new motorway

Crossing over main North Island rail line (NIMTR)

  • A bridge is being built to cross the North Island Main Trunk rail line
  • It is the largest structure on the project
  • The bridge will have two decks but share piers along the length
  • Six spans will carry the motorway between 2 large embankments for a total of 120 metres
  • Earthworks will form a platform alongside the motorway east of the bridge for the future rail link to the Manukau city centre

Lambie Drive Interchange

  • A new bridge allows Lambie Drive to pass over the new motorway
  • A rail underpass is being constructed for the future rail link to Manukau city centre
  • Main entry and exit point for Manukau Central Business District traffic to access SH1 and SH20
  • Traffic going to and from Manukau city centre will use this as a major access point for the completed motorway in both directions

Wiri Station Road

  • A new bridge has been constructed to allow this important road to pass over the new motorway.

Barrowcliffe Place (Manukau City Council)

  • Construction work will allow direct bridge access from the undeveloped area south of Wiri Station Road, across the motorway to Manukau city centre
  • Includes a local road bridge and pedestrian access

Great South Road

  • A bridge has been constructed to allow the new motorway to pass under Great South Road

SH1 - SH20 Interchange

  • The SH1 and SH20 motorways will join at this triple-level interchange
  • Features a 240 metre curved flyover with 10 spans
  • The exit ramp from SH1 to Great South Road has been realigned
  • New ramp from Redoubt Road to SH1 has been opened
  • Traffic travelling from Auckland and from the south will have direct access to SH20, to Auckland International Airport and the Western Ring Route
  • Traffic travelling from SH20 will be able to join SH1 travelling both north and south
  • Construction is taking place in three stages, from early 2007 until early 2010

Manukau rail link (Manukau City Council)

The project includes preparatory work towards the construction of a rail link to the Manukau city centre from the main North Island rail line - adjacent to the motorway. A Manukau City Council and ONTRACK funded project, it will form a 1.8 kilometre connection between the existing main trunk line at Wiri and a new station at Manukau city centre.

At the same time as the motorway project work, Manukau City Council has also completed a separate project to connect Nesdale Ave with Cavendish Drive.

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Benefits

The SH20 Manukau Extension project will deliver the following benefits:

  • Improved access to and from Auckland International Airport
  • More reliable trip times and improved commute times
  • Considerable relief to local roads within the Manukau city centre area, such as Cavendish Drive, Great South Rd and Wiri Station Road
  • A direct link from SH1 for traffic heading to the airport and central and western suburbs, via SH20
  • Better rail transport for Manukau by preparatory work on rail link and station for Manukau city centre
  • Key connection to support future growth at the Wiri and Auckland International Airport business zones, as well as an expected population increase of 40,000 people at the new suburb of Flatbush

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Timeline

  • Construction started - June 2006
  • Construction completed - December 2010