Contents: History of the South Western | The Manukau Extension | Completed Images | Construction Images | Merging issues at the Southern

The South Western Motorway & Western Ring

The South Western Motorway (SH20) has been under construction to connect to motorways in the north and south since the 1970s. From 1997 to now the motorway has been extended in both directions. The main purpose of the South Western Motorway is to provide connections to the Auckland Airport. Eventually when connected to existing motorways the motorway will be an alternative to the Southern motorway - completing the currently under construction Western Ring Motorway Network.

The first section of the South Western Motorway started construction in late 1977, the section was only a short approach to the old Mangere bridge bypassing the busy Onehunga area. The northbound Mangere Bridge after a very long construction process was completed in March 1983. It connected the already used Onehunga bypass to the newly completed crossing to create a total section between Neilson Street and Coronation Road of 1.8km.

Recent activity:
- In 1997 the Coronation Road to Puhinui Interchange, and link to Kirkbride Road section was completed.
- The Mt Roskill Extension in May 2009 opened; extending from Hillsborough Road to Maioro Street in the north-west.
- In mid-2010 both the Mangere Bridge duplication & surrounding widening and the Manukau extension opened. Widening the existing motorway and bridge and connecting the 1997 section to the Southern Motorway respectively.
- One project on the South Western Motorway is still to be completed; the Waterview Connection between the Mt Roskill Extension and the North Western Motorway.

This project is one of the projects of the Western Ring Route. The Western Ring Route will offer a much needed alternative to the congested Northern and Southern Motorways. There are seven projects on this network with five now completed, the Waterview Connection and North Western Widening projects are yet to be completed.

The Manukau Extension Project

Fully Completed: December 2010. $240m.

The new section of motorway is 4.5km in length and features five overbridges and five interchanges including the major interchange with the Southern Motorway.

Nesdale, Liverpool and Cavendish Drives will be widened to four lanes - offering easier access to main roads in Manukau and offering an improved connection for Roscommon Road to Southern Motorway traffic heading northbound.

Southbound lanes opened on Sunday the 29th of August 2010 and westbound lanes opened on Monday the 27th of September 2010.

To see a larger version of the map below click here.

Above: Lambie Drive interchange in detail.	Above: South Western/Southern interchange in detail.

Completed Images

The southbound lanes opened on Sunday the 29th of August 2010 and the westbound lanes opened on Monday the 27th of September 2010. The westbound Roscommon Road to Puhinui Road connection, the Wiri Station Road extension (to Lambie Drive), and the link from southbound Southern will not open until December 2010.

Below are completed images of the motorway extension.

Above: From Lambie Drive looking south/east.	Above: From Lambie Drive looking west, with the Lambie Drive southbound on ramp.
Above: Looking west from Lambie Drive.	Above: Roscommon Road/Puhinui Access and South Western interchange. Opens December 2010.
Above: Wiri Station Road extension at the Lambie Drive Interchange.	Above: Taken from Great South Road overbridge on the Open Day.
Above: Looking along the South Western by Wiri Station overbridge.	Above: Lambie Drive on-ramp Ramp Signalling.

Construction Images

The project commenced construction in 2006, and is yet to be completed by December 2010.

Below are construction images of the motorway extension.

Above: From Plunket Ave looking east. (2008).	Above: From Lambie Drive looking west. (2008).
Above: Lambie Drive interchange bridge under construction. (2008).	Above: South Western/Southern Interchange under construction. (2008).
Above: South Western/Southern Interchange under construction. (01/10).	Above: Great South Road overbridge looking west. (01/10).
Above: Looking east toward the Lambie Drive overbridge. (01/10).	Above: Plunket Road Overbridge under construction. (01/10).
Above: Roscommon Road/Puhinui Access and South Western interchange under construction on the eastern side. (01/10).	Above: South Western/Southern interchange. (07/10).
Aerial Shots taken December 2008 by David McArthur

Merging issues at the Southern

Since the opening of the Manukau Extension significant and problematic congestion has been created on the Southern Motorway. This occurs in the afternoon peak period. Before the motorway opened traffic usually banked up between East Tamaki and the Redoubt Road off-ramp. Now congestion occurs between Highbrook and Takanini. Not only does the congestion exist, it also lasts longer. Congestion used to occur between 5pm and 6.15pm, now it exists between 4pm and 6.40pm every weekday.

Despite the obvious reason for the congestion to occur (extra traffic), there are two reasons as to why congestion has occurred in the area:

1. The layout of the merging lanes is poor. There are two lanes entering the Southern Motorway from the South Western. The right hand lane has to merge with the slow lane immediately, and the left lane has to merge around 400m south with the slow lane again. To make matters worse, the left lane merges with Southern motorway traffic on a corner, and some drivers have no idea the lane is about to end.

2. The section of the Southern Motorway in question should have had extensive work completed in the surrounding area of the interchange in order to properly absorb the traffic. The Redoubt Road on-ramp still exists, and enters right before the South Western Motorway does. The South Western Motorway joins the motorway with no lanes; it must merge into the existing three lanes. Once at Hill Road in Manurewa (around 2500m away from the above on-ramps) the motorway drops a lane! Now the six lanes of traffic added goes to three then another squeeze into two lanes!

What should have been completed in the area is this: The South Western enters on their own lane which runs for about two kilometres to end at Hill Road (as an auxiliary lane[?]), all traffic from the South Western that is continuing south moves into the second lane, which has Redoubt Road traffic on it. The second lane continues all the way to at least Takanini as three lanes total. Like this:

Above: The layout that should have been constructed.

Ramp Signalling should not exist on the South Western motorway merge with the Southern; it will defeat the purpose of providing an alternative to the southern motorway by possibly jeopardising gained time. Ramp Signalling should exist at the Redoubt Road on-ramp (as it does), which means the second lane (from the above scenario) is free for South Western traffic to move into before it ends at Hill Road.

Currently a third lane extension all the way to Papakura is proposed but funding has not yet been allocated for it. Ramp Signalling has been installed on three lanes of the on-ramp and has lessened the extent of the congestion on the Southern and also lessened the extent of congestion that the temporary lane drop caused on the South Western. Ramp Signalling here should be a temporary measure.

The merge at Manukau is a disaster, it should be fixed and fast. Aucklanders do not want motorways that make matters worse.

This has been written by the website's author Benjamin Paul. This website is not run by the NZTA or government. Click here for about.