SH1 Wellington Improvements

Project update

21 October 2025

Artist's impression of the proposed second Mt Victoria Tunnel

Minister announces investment case endorsement

A solution to some of Wellington’s longstanding bottlenecks is one step closer as Transport Minister, Chris Bishop, announced yesterday the NZTA Board’s endorsement of the SH1 Wellington Improvements investment case. 

The project will see the construction of a second Terrace Tunnel, a second Mt Victoria Tunnel, and a major roading upgrade at the Basin Reserve. It will also include supporting improvements on the remaining state highway corridor. It will allow people and businesses to get where they need to go faster and more reliably, while unlocking productivity and regional economic growth.

As well as endorsing the investment case, the Board also approved funding for the next stage of the project’s development – pre-implementation. This means NZTA can get on with the next stage of design work, secure consents and purchase the property required for the project.

Tolling: The recommended option also proposes tolling to support the construction and maintenance of the project.

Project benefits

• Up to 10 minute future travel time savings at peak times on state highway journeys to Wellington airport, hospital and CBD.
   
• Improved travel times on the number 2 and Airport Express buses — if rerouted through Mt Victoria Tunnel.
   
• Up to 40% improvement in future travel time reliability, giving more certainty on how long it will take people to get where they need to go.
   
• Improved walking and cycling with a new 3.6-metre-wide shared path through Mt Victoria Tunnel.
   
• Reduction in traffic on local roads.
   
• Improved productivity and economic growth.

A summary of the investment case and project benefits is available on the project website.

Next steps

The project is now in the pre-implementation stage, which is expected to take approximately 3 years. During this stage, NZTA will continue to develop project designs, further investigate options for tolling, purchase the property required for construction and secure any necessary consents and approvals through the Fast-track Approvals Act (2024).

Oct 2025

• Engagement begins with landowners whose property may need to be purchased.

Mid-Nov 2025

• Community engagement begins.
• Mt Victoria Tunnel geotechnical investigations begin.

Mid-2026

• Fast-track Approvals Act application lodged.

Two drill rigs will work in parallel to minimise the duration of disruption. One of the types of rigs is shown in the image to the right. To keep everyone safe, the investigation works will require the temporary closure of some sections of track in the Hataitai Park area of the Wellington Town Belt. Track signage will be in place,  and the latest information will be on the project webpage.

Drilling into the details...

The boreholes will be between 40m and 80m in depth, and some will be inclined from horizontal at angles between 50° to 55°.

The ground conditions we’re anticipating finding are silty soils, overlaying in situ Rakaia terrane sandstone and mudstone (locally known as Wellington greywacke). Drill rigs will use a triple tube system, suitable for obtaining high-quality core samples in challenging geological conditions.

Core samples will be extracted in 1.5 m long ‘runs’ and logged on site by engineering geologists. Some parts of the core sample will be prepared and sent to a Wellington laboratory for further testing and analysis. Lab testing provides quantitative data on shear strength, compressibility, permeability, plasticity, and grain size distribution.

Taking soil and rock samples is fundamental in geotechnical investigations because it provides direct, physical evidence of subsurface conditions. This is essential for identifying rock strength, joints and faults, then planning the tunnel alignment and retaining structures.

The latest information about these investigation works will be available from the Mt Victoria geotechnical investigations webpage.

More information

For more information on the SH1 Wellington improvements project, contact us at SH1WgtnImprovements@nzta.govt.nz

Visit our website www.nzta.govt.nz/sh1-wellington-improvements