The Third Main line

The rail line between Westfield and Wiri is the busiest part of Auckland’s (and New Zealand’s) rail network with 380 freight services and 1500 passenger services travelling through the area each week.

KiwiRail is building a third rail track alongside the two existing ones to ease congestion and provide faster train journeys and reduce delays.

What is a 'Third Main'?

Auckland’s rail network currently has two sets of tracks and operates like a two-lane road, with trains travelling in different directions on each track.  These tracks are call the ‘up main’, for trains heading   north and the ‘down main’ for trains heading south.   

The ‘third main’ is a third set of tracks that will act as a passing lane for trains through this busy part of Auckland.   

This upgrade will:

  • Allow for anticipated growth in both freight and passenger rail services ahead of the opening of the City Rail Link
  • Improve rail links to key freight hubs, including KiwiRail’s Westfield and Southdown freight terminals and the Ports of Auckland inland port at Wiri. 

Preparatory work began in late 2020 and the project will be completed ahead of the opening of the City Rail Link.

The New Zealand Government has allocated $315 million from the New Zealand Upgrade Programme for this important project. 

Once the Third Main Line is built, trains will use the new rail line from south of Wiri to north of the Westfield junction on the Eastern Line. There will also be new track connections so trains can move from one rail line to another.

Works are focused around three locations:

  • Westfield and Wiri junctions – Third Main and track reconfiguration 
  • Middlemore to Puhinui - Third Main
  • Quay Park - Track reconfiguration to allow for better freight train movements in and out of Ports of Auckland
Project works map 200608

Current status

Works are largely complete at Westfield and Wiri junctions as well as Quay Park at the entrance to the Ports of Auckland in downtown Auckland

In April 2023, rail track was laid from Puhinui Station to just north of Papatoetoe Station. The only remaining section of new track for the Third Main is from south of Middlemore Station to just north of Middlemore. 

The project in detail

Westfield Junction

This junction between the Eastern and Southern lines also provides access to KiwiRail’s Westfield and Southdown freight terminals where freight is loaded onto trains for transportation.

Improving the entry and exit points to the freight terminals and across the junctions will allow freight trains to move more efficiently and will mean slower moving freight trains won’t delay passenger trains.

Wiri Junction

At Wiri Junction trains travel to Ports of Auckland Inland Port, Auckland Transport’s EMU Depot (where electric trains are housed and maintained), the Manukau line and the Southern line.

The new additional line will mostly be used by freight services and will prevent these slower, longer trains from delaying faster passenger services by separating freight and passenger trains.

Middlemore to Puhinui

Constructing an additional rail line on the western side between Middlemore to Wiri will ease congestion by:

  • Reducing conflicts between freight and passenger services
  • Making room for more frequent freight and passenger services
  • Enabling express trains to pass stopping services

Works started in late 2021 and are largely complete.

Quay Park

The rail layout is being changed to provide separate rail access to the Ports of Auckland freight yard. This will allow for more operational flexibility and for the separation of freight and passenger trains.

To create space for the new track layout at the approach to Quay Park, a small number of trees alongside Tamaki Drive, including Pōhutakawa, need to be trimmed or removed. KiwiRail has worked hard to limit the number of trees affected and will plant about 35 new trees at an alternative safe site.

Small W2POA map 200608