Government investigates 4km tunnel under Wellington

The government is asking Waka Kotahi (NZ Transport Agency) to investigate a Long Tunnel option for Stage Highway 1 in Wellington.

The twin two-lane 4km tunnels would run from north of the Terrace to Wellington Road near the suburb of Kilbirnie.

Transport Minister Simeon Brown says the tunnel option strongly aligns with the government's priorities in the Government Policy Statement on Land Transport (GPS).

Brown told Morning Report the transport agency presented a compelling case for why the option should put the option back on the table.

"The Long Tunnel option has the potential to deliver up to 15-minute travel time savings between the region and Wellington airport, compared to around 2-3 minutes for the current parallel or diagonal tunnel proposals at Mt Victoria and the Basin," Brown said.

"Effectively prior to going into the Terrace tunnel, there'd be a new tunnel it'd be two two-lane tunnels. It would go all the way under Wellington, under Mt Vic tunnel and then come out at Wellington Road near the airport," he told Morning Report.

Whether there needed to be an exit half way through, potentially near the Basin, would also be looked into, he said.

"The option would also see better urban amenity through greater reallocation of surface level road space to active modes and public transport in the CBD and greater opportunities for housing intensification. Enhanced regional connectivity to the airport and hospital would also be achieved with reduced city and state highway congestion," Brown said.

"The option would also mean less construction disruption for local traffic as the Long Tunnel option could be built with less disruption to the city centre and less impact on public and private properties required for other options."

Waka Kotahi has been asked to consider and provide advice on the technical feasibility, cost, and funding and financing options for the proposal.

The investigation work would be completed by the middle of the year and the government would then make decisions, Brown said.

Planning of the duplicate Mt Victoria Tunnel and Basin Reserve project continued, he said.

Wellington mayor Tory Whanau said she would rather see the government focus on water reforms than a potential SH1 tunnel.

Whanau said she was interested in the possibility of freeing up land, but wanted to know what the environmental impact would be.

"Ultimately, we know that climate change is already here. We need to offer people more low emission ways of getting around and lessen the amount of cars on the road, which reduces congestion and frees up our streets for people," she said.

"As with any new transport project I would like to see what the climate change impact of the work will be. However, I am interested in looking at opportunities this would deliver for the city in terms of freeing up surface-level road space for housing, walking, cycling and public transport as well as any urban development opportunities.

"I also want to ensure the government keeps water reform as a top priority before this work proceeds."