Project introduction

When Transmission Gully opens it will become State Highway 1 (SH1). The former SH1 between Linden and Mackays Crossing will be renumbered State Highway 59 (SH59) in advance of Transmission Gully opening.

  • Estimated project dates

    Dec 2021


When Transmission Gully opens it will become the main route in and out of Wellington and will be assigned the SH1 designation. As the current section of SH1 between Linden and Mackays Crossing will remain a state highway until a decision is made on its future, it will be renumbered SH59. The renumbering will take place on Tuesday 7 December. Despite the change in state highway number, the route will not change.

This is part of a wider project to ensure the existing state highway network, and everyone who uses it, is ready for the opening of Transmission Gully. Renumbering this section of highway in advance of the opening allows clear and appropriate signage to be in place to ensure clear communications in the event of crashes or incidents, and help people – whether locals, visitors, deliveries or emergency services – find their way around the network easily.

Renumbering this section of road as SH59 will signal that Transmission Gully, as SH1, is to be the spine of the state highway network and carry the majority of inter-regional traffic, especially freight.

The below maps show the current highway numbers, and the new highway numbers that will take effect when Transmission Gully opens.

Overview map

Mackays Crossing Interchange map

Kenepuru Interchange map

View larger maps [PDF, 1.6 MB]

Frequently asked questions

  • Why does this section of road need to be renumbered?

    Without this change there would be confusion when using the regional road network, particularly to people unfamiliar with local roads.

    The renumbering will identify the new Transmission Gully motorway as the ‘spine’ of the road network and help people know which highway they need to be on to reach their destination.

    It is expected that the majority of vehicles, including heavy vehicles, will use SH1 Transmission Gully as the main route in and out of Wellington.

  • Where will State Highway 59 begin and end?

    SH59 will run from the SH1 Mackays Crossing interchange to the SH1 merge at Linden. The northern end of SH59 will include a new section of road being built opposite the Paekākāriki off-ramp.

    Please refer to the map for more detail.

  • Why are you renumbering SH59 before the Transmission Gully motorway is open?

    While the opening of the new Transmission Gully motorway has been delayed by COVID-19 restrictions, the work to prepare the wider state highway network for the changes needs to continue as planned.

    This means SH59 will be renumbered in advance of Transmission Gully becoming SH1, creating a small break in SH1 between Mackays Crossing and Linden.

    The renumbered section of state highway will then be ready, with no further changes required, when the new motorway opens.

  • Have you made a decision on the future of the state highway between Linden and Paekākāriki?

    The renumbering of this section of SH1 to SH59 does not preclude any future decision on whether this section of road should remain a state highway in future.

    The Transmission Gully Board of Inquiry requires Waka Kotahi to consult with Porirua City Council, Greater Wellington Regional Council, Ngāti Toa Rangatira, Paremata Residents Association and Plimmerton Residents Association on the future of this section of state highway. This consultation includes consideration on whether it should remain a state highway or become a local road. Waka Kotahi has previously advised of its preliminary position that this section of road should remain a state highway.

    Media release: Waka Kotahi considering future of SH1 and SH58 (13 August 2020)

    A final decision on whether this section of road is revoked will only be made following the necessary consultation.

  • I think my property may be affected, what do I need to do?

    There are a small number of people and businesses who will be affected with an address change. Their address will change from State Highway 1 to State Highway 59. Waka Kotahi has been working with NZ Post, Kāpiti Coast District Council and Porirua City Council to prepare for this change.

    NZ Post will change all the affected postal addresses in their database system so there will be no need for redirections. However, the occupiers/landowners will need to update any legal documentation, as well as informing friends and family who send them mail, or if they have their address saved on an online site (such as Trade Me).

    Once the updates are live in NZ Post’s system, anyone will be able to search for the new address using the online postcode finder.

    Address and Postcode Finder(external link)