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SH16 Causeway Upgrade Project

Updated: 19 May 2015

The NZ Transport Agency has engaged the Causeway Alliance to raise and widen 4.8km of State Highway 16 in Auckland, from Great North Road west to the Whau River bridge just before Te Atatu.

The Causeway Upgrade Project involves raising the motorway 1.5 metres to prevent flooding and debris, and widening it to provide additional capacity in both directions. The shared path alongside the motorway is being raised, widened and upgraded, too. The work is being completed in stages so that disruption to the community, our environment and to traffic is kept to an absolute minimum.

The causeway runs beside the Motu Manawa – Pollen Island Marine Reserve.  The Causeway Alliance is ensuring that the project will have as little impact as possible on the marine reserve.

Penguins. Patiki and Rosebank Domain aerial view. The causeway upgrade.

SH16 westbound lane layout changes – Rosebank to Te Atatu

From Tuesday 2 June.

Click here for more information.

The Causeway Alliance

The Causeway Alliance is made up of AECOM, Coffey, Fulton Hogan, Leighton Contractors, Jacobs and the NZ Transport Agency itself, bringing together specialist skills in a range of safety, engineering, design, construction, environmental protection, management, commercial and support disciplines.

The Causeway Upgrade Project will be finished along with other projects - being delivered by different project teams for the NZ Transport Agency - at St Lukes, Lincoln Road and the Te Atatu Interchange by the time the Waterview tunnels open in 2017. Together those projects are completing the Western Ring Route road of national significance, an efficient motorway alternative to State Highway 1 (which runs through the city and over the Auckland Harbour Bridge), for traffic travelling south/north, and north/south.

Key benefits of the project for Auckland

The Causeway is a key part of the Western Ring Route - one of the Government's seven roads of national significance to help promote economic growth. Once completed, the Western Ring Route will provide a strategic alternative to SH1, central Auckland and the Auckland Harbour Bridge. It will link with the Waterview Connection project and its new interchange at Great North Road - connecting SH16 with the Southwestern Motorway (SH20).

The causeway upgrade will provide the following benefits to road users:

  • Improve traffic flow and travel times with the addition of more lanes
  • Less flooding on the causeway
  • Quicker bus trips
  • Improve pedestrian and cyclist access across the motorway.


As part of the Causeway Upgrade Project, the Causeway Alliance is:

  • Widening the causeway to add lanes and create more capacity
  • Raising the causeway and the adjacent shared path/cycleway to reduce flooding
  • Constructing new bus priority lanes on the motorway shoulders
  • Improving access across the motorway for pedestrians and cyclists

Phasing graphics

The graphics below show how State Highway 16 between Great North Road and the Whau River Bridge near Te Atatu is being raised and widened.

Staging Schematic

View larger version (PDF, 701KB)

The two images show the causeway in profile as it is now and as it will be by early 2017. You can see at a glance the improvements that will be made to the height and capacity of the causeway.

before construction
Current Causeway configuration

after construction
Final causeway configuration by early 2017– complete median, final pavement and stormwater

View larger version (PDF, 2MB)

The goal of the Causeway Upgrade Project is to help Auckland become a world class city, making life easier for residents, commuters, cyclists, pedestrians, businesses, freight operators and tourists, while looking after our environment and each other in the process. There's lots of work ahead of us to achieve what we have set out to do. Your ongoing cooperation and support will make sure we reach that goal together.

Causeway Alliance logo.

Key facts

Other names: SH16 Causeway

Part of:Western Ring Route, a Road of National Significance

Construction start date: May 2013

Estimated completion date: Early 2017

Location: SH16 between Great North Road Interchange and Whau river bridge before the Te Atatu interchange

Estimated cost: $220m