ICW demystifier: What is the ‘second Mt Victoria tunnel’ all about?

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What do NZTA and central government say it will achieve?

(From NZTA website)
Travel on SH1 to key destinations including the CBD, airport and hospital will be faster and more reliable, encouraging less traffic on local roads.

Less traffic on local roads enables opportunities for greater use by public transport and other modes. Improved walking and cycling facilities through the Mt Victoria Tunnel will improve options for active travel.

Currently, State Highway 1 (SH1) through Wellington is heavily congested at peak times, causing delays and unpredictable journey times and increasing traffic on local roads as people seek alternative routes. Without investment, as the regional population grows, travel times and reliability will worsen, hampering productivity and restricting economic growth.

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What are the headlines? (ChatGPT’s summary of the project)

1. 1. SH1 Wellington Improvements (RoNS)

   • The project is part of a Road of National Significance (RoNS) for SH1 through Wellington. NZ Transport Agency+3NZ Transport Agency+3Inside Government NZ+3

   • It includes three major pieces:

     • A second Mt Victoria Tunnel

     • A duplicate Terrace Tunnel

     • Major upgrades around the Basin Reserve The Beehive+2NZ Transport Agency+2
       

   2. Design of the Second Mt Victoria Tunnel

   • The proposed second tunnel would run parallel to the existing Mt Victoria Tunnel. The Beehive+2NZ Transport Agency+2

   • It would have 2 eastbound lanes (towards the airport) in the new tunnel. NZ Transport Agency+1

   • The existing Mt Victoria Tunnel would be retrofitted to provide 2 westbound lanes (into the city), removing the current shared path inside that tunnel. NZ Transport Agency+2NZ Transport Agency+2

   • A 3.6 m-wide shared walking & cycling path is proposed, fully separated from traffic, in the new tunnel. NZ Transport Agency+1
     

   3. Basin Reserve Upgrades

   • The plan includes grade separation between state highway traffic and local roads around the Basin Reserve, likely involving an extension of the Arras Tunnel. NZ Transport Agency+1

   • The goal is to reduce congestion and make traffic flows more reliable, especially for buses and freight. The Beehive+1
     

   4. Wider Corridor Upgrades

   • Improvements to Ruahine Street and Wellington Road, widening to two lanes in each direction east of Mt Victoria. NZ Transport Agency

   • In the city centre: three lanes on Vivian Street, and better traffic signal optimisation at intersections. NZ Transport Agency

   • A second Terrace Tunnel: the existing Terrace Tunnel will have 2 lanes northbound, and the new duplicate tunnel will handle 2 lanes southbound. NZ Transport Agency+1
     

   5. Benefits Forecasted

   • Travel time savings: Up to ~10 minutes in peak periods (for trips from northern suburbs to CBD, hospital, airport) according to NZTA. The Beehive+1

   • Reliability: Travel time variability (i.e. unpredictability) could improve by up to ~40%. NZ Transport Agency

   • Modal shift / active transport: The shared path in the second tunnel is intended to encourage walking/cycling; also improved public transport reliability. Scoop Auckland

   • Resilience: Having a second tunnel increases route security — in case of incidents in one tunnel, traffic flow is less likely to be completely disrupted. NZ Transport Agency
     

   6. Funding & Cost

   • The total “investment envelope” (design, consenting, land acquisition, construction) is estimated between NZ$2.9 billion and NZ$3.8 billion. NZ Transport Agency

   • There is mention of tolling to support construction and maintenance of the new roads. NZ Transport Agency
     

   7. Environmental / Land Impacts

   • The new tunnel would affect some land in the Town Belt. RNZ

   • Property acquisition will likely be part of the project (for road widening etc). RNZ

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Who would be affected by the construction and changes?

• Anyone using the Basin Reserve area of the central city and feeder roads. Traffic movement around the Basin Reserve would be altered - for example the current North to South route around the Basin Reserve would become one way - South to North.

• Te Aro and Mt Cook residents: major construction

• Mt Victoria residents: major construction, removal of housing, some routes from Mt Victoria Streets to the Kent Terrace restricted.

• Hataitai residents: major construction, parts of the existing road from the tunnel widened using parts of the Town Belt.

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Where can I see what’s planned?

• NZTA website - project overview (November 2025)

• NZTA engagement brochure (PDF)

• NZTA Community engagement information

• NZTA video flythrough

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How can people provide their feedback?

(NZTA website):
NZTA opened a 4-week engagement period on Monday 17 November. It runs until Sunday 14 December 2025.

The website says:
Information will be available on the project web page and at information days during this period. Come and meet with the project team then complete the feedback survey online.

We’ll publish a summary of what we heard from the community in February next year and consider your feedback as we continue to refine the project design.