The Green Party is calling on the Government to complete light rail and improve walking, cycling and bus journeys across Wellington before digging new high-carbon tunnels.
The Government is exploring ways to transform the capital's public transport infrastructure as part of the $6.4 billion Let's Get Wellington Moving programme.
Its preferred option includes light rail from Wellington Station to Island Bay; a new tunnel through Mt Victoria for public transport, walking and cycling; and upgrades to improve traffic flow at the Basin Reserve.
"Where previous governments have failed to plan for the long term, we are committed to supporting Wellington to reach its future potential," Deputy Prime Minister Grant Robertson said on Wednesday in a statement.
“This is a once-in-a-generation opportunity to shape Wellington’s future, align transport and urban development, and help to address the climate crisis by moving more people with fewer vehicles."
Robertson said up to 80,000 more people will be estimated to be living within the city limits by 2050, and 25% more people will be commuting into the central city each workday.
"Light rail will support more people living centrally, close to where they work, study and live their lives," he said.
Greens transport spokesperson Julie Anne Genter said while the party is "pleased light rail will finally be made a reality in Wellington" and a "new dedicated walking and cycling tunnel are also to be welcomed", the Government’s preferred option is "not the best for the climate overall".
"The tunnels will be high-carbon and high-cost, and could also delay the delivery of safe walking and cycling to the east,” Genter said on Wednesday in a media release.
"We have a once in a generation opportunity to address the climate crisis and make Wellington more liveable. Our cities can be designed to address the climate and housing crisis. But successive Governments have been stuck in the same old mindset of trying to reduce congestion by building another expensive bit of road – and it seems this Government is thinking the same way.
"Wellingtonians have consistently said they want sustainable, city-enhancing public transport. The preferred option of light rail is the best way to support climate-friendly urban development and increase affordable housing and transport."
She said the party is calling on the Government to "guarantee that public and active transport will be transformed before the sod is turned on a longer tunnel at the Basin reserve" as it looks towards which transport projects should be prioritised.
Genter added that the proposed "unnecessary changes" to the Basin will have a "tiny effect on travel times" for motorists, with Let's Get Wellington Moving modelling showing that it "saves about a minute and a half off a trip from Johnsonville to the airport at peak time compared to no change at the Basin".
"The reason for this is that the congestion just moves along to the next set of lights, the next bottleneck. Increasing capacity for cars will not make it easier to get around Wellington. It will simply move the congestion to another part of the city."
The party said its preferred option would have "avoided an unnecessary extension of the tunnel at the Basin", which "would have delivered a similar boost to housing as the option chosen by the Government - but better public transport options and climate outcomes".
"Not only is our preferred option the most climate friendly, it’s also the most affordable - meaning we can use the moment to improve public and active transport elsewhere in the Wellington region."
Genter raised the concerns in the House on Wednesday, telling Transport Minister Michael Wood the Government's preferred option with the additional tunnel through Mt Victoria would have, according to modelling, double the emissions built-in and reduce emissions more slowly than the Greens' preferred plan.
Wood said the Government's chosen option would deliver the "highest degree of benefits" for encouraging people to move away from their cars and into other modes of transport.
Wood said the additional Mt Victoria tunnel and the improvements around the Basin Reserve would make taking public transport, walking and cycling more attractive.
He acknowledged that building any significant transport infrastructure was coupled with "significant embedded emissions". But, he said achieving net-zero carbon emissions by the mid-2030s was possible because the Government had planned to further intensify housing.