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 State Highway 20 and State Highway 1 at Manukau City. The work includes five motorway crossings over local roads and streams, as well as the main North Island rail line.
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-hectare site area.
- 920,000 m³ of earthworks.
- 7 sedimentation ponds.
- 16.8 km of drainage.
- Estimated cost – $210 million.
- Construction commenced in June 2006.
- Construction completed in January 2011.
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 State Highway 20 and State Highway 1 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 State Highway 20 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 two 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 State Highway 1 and State Highway 20.
- 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 State Highway 1 and State Highway 20 motorways will join at this triple-level interchange.
- Features a 240 metre curved flyover with 10 spans.
- The exit ramp from State Highway 1 to Great South Road has been realigned.
- New ramp from Redoubt Road to State Highway 1 has been opened.
- Traffic travelling from Auckland and from the south will have direct access to State Highway 20, to Auckland International Airport and the Western Ring Route.
- Traffic travelling from State Highway 20 will be able to join State Highway 1 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.
Benefits
The State Highway 20 Manukau Extension project has delivered 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 Road and Wiri Station Road.
- A direct link from State Highway 1 for traffic heading to the airport and central and western suburbs, via State Highway 20.
- 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.
