MIN-4667 SH1 Wellington Improvements
10 October 2024
This advice provides an overview of the Second Mt Victoria Tunnel and Basin Reserve Upgrade including the
Terrace Tunnel duplication (SH1 Wel ington Improvements). The advice covers project scope and the option
for information on consenting, opportunities for bus prioritisation, road pricing, and early opportunities to start
progressing work on the corridor.
___________________________________________________________________________
NZ Transport Agency Waka Kotahi (NZTA) response:
Introduction
• Improving State Highway 1 (SH1) from the Wellington Urban Motorway through the city centre to the
airport has consistently been part of Wellington’s transport strategies. It was included in the 2009
Wel ington Northern Corridor (Levin to Wel ington) Road of National Significance (RoNS) project, which
included a duplicate Terrace Tunnel, grade separation at the Basin Reserve and a Second Mt Victoria
Tunnel.
• The 2019 Let’s Get Wellington Moving (LGWM) ‘Recommended Programme of Investment’ also included
the same tunnel duplications and upgrades at the Basin Reserve, although the Terrace Tunnel duplication
was omitted from the Indicative Programme that was taken forward by LGWM due to affordability
constraints.
• The objective for the SH1 Wel ington Improvements is to provide more efficient and reliable access to
support regional economic growth. The option that combines the Second Mt Victoria Tunnel and Basin
Reserve Upgrade and the Terrace Tunnel duplication into a single RoNS project within Wel ington City will
significantly improve achievement of this objective and the key strategic priorities listed in the Government
Policy Statement on Land Transport 2024 (GPS).
SH1 Wellington Improvements
Option scope
• The scope of this option for SH1 Wellington Improvements includes a Second Mt Victoria Tunnel, Basin
Reserve Upgrade and Terrace Tunnel duplication. These elements are described below:
a. A Second Mt Victoria Tunnel will deliver a new 0.7km tunnel parallel to the existing tunnel,
together they will provide two general traffic lanes in each direction. s 9(2)(ba)(ii)
s 9(2)(ba)(ii)
b. The Basin Reserve Upgrade wil provide grade separation between SH1 and local roads. This will
be achieved through an extension of the Arras Tunnel and moving the westbound SH1 traffic to
the northern side of the Basin Reserve. Local traffic, including public transport, wil pass over SH1
on the western side of the Basin Reserve.
c. A duplicate Terrace Tunnel comprising a new 0.5km tunnel parallel to the existing Terrace Tunnel
with tie-ins.
d. Network improvements to maximise benefits including s 9(2)(ba)(ii)
• A plan showing the SH1 Wellington Improvements option is contained in Appendix A.
• s 9(2)(ba)(ii)
a range of different staging and implementation approaches wil be considered
to best achieve programme and value for money outcomes.
Costs and benefits
• The project would result in significant travel time savings in peak periods, reducing traffic travel times from
the Wel ington Region to the CBD, hospital and airport by around 10 minutes.
• s 9(2)(ba)(ii)
Consenting strategy
• s 9(2)(ba)(ii)
•
•
•
s 9(2)(ba)(ii)
Public transport - included bus priority measures
• Grade separation of the Basin Reserve removes the conflict between local movements and SH1 traffic,
delivering significant benefits to both. s 9(2)(ba)(ii)
• SH1 Wel ington Improvements are forecast to contribute to the 11 minutes of travel time savings for Bus
Route 1 in the AM peak between Island Bay and the city centre. SH1 Wel ington Improvements to the east
of Mt Victoria Tunnel are forecast to contribute to the 9 minutes of travel time savings for Bus Route 2 in
the AM peak between Miramar and the city centre.
Out of scope public transport improvements
• SH1 Wel ington Improvements will result in a reduction of traffic on local city streets, and this wil support
Wel ington’s North-South, East-West and Harbour Quays bus corridors as identified in the GPS. SH1
Improvements wil further support the local and regional councils broader public transport upgrades across
Wel ington City by reducing traffic in the city centre.
• Traffic model ing estimates s 9(2)(ba)(ii)
a 30 percent reduction in southbound volumes
along the Harbour Quays could be realised when the Second Mt Victoria Tunnel, Basin Reserve Upgrade
and a Terrace Tunnel duplication are delivered.
s 9(2)(f)(iv) and s9(2)(g)(i)
Early opportunities to start work on the corridor
s 9(2)(ba)(ii)
Next steps and timeline
• The first step is to complete the investment case for NZTA Board consideration. This wil include work to
develop the scheme design for the Second Mt Victoria Tunnel, Basin Reserve Upgrade and a Terrace
Tunnel duplication. Key tasks in this phase include:
a. Undertake detailed geotechnical investigations to inform design of tunnels.
b. Update cost estimate and risk assessment.
c. Undertake constructability reviews, establish likely staging and develop main construction
procurement strategy.
d. Identify and develop early construction opportunities.
e. Identify the recommended road pricing option.
f. Undertake stakeholder consultation.
g. Confirm property acquisition strategy.
s 9(2)(ba)(ii)
Noted by Minister ☐
