A bold proposal for Wellington's transport system could see new tunnels at Mt Victoria and The Terrace, and bridges or tunnels at the Basin Reserve.
Let's Get Wellington Moving, a group made up of the city and regional councils, and the New Zealand Transport Agency released the four ideas this evening:
Spokesperson Barry Mein said the scenarios built upon each other, starting with improvements in the CBD, to large-scale change that would see new tunnels built under Te Aro, at Mt Victoria and The Terrace.
Improvements would also be made at Basin Reserve, and could include tunnels and bridges.
Mr Mein said the bridges would be smaller than a proposed flyover that was rejected by a Board of Inquiry in 2014.
Light rail has also been put out as an option to open up public transport from the city to the hospital and airport.
Mr Mein said as Wellington grew, building new roads was not enough.
"So it's a case of having to move more people without moving more vehicles, and so the challenge is how can we encourage people to travel on public transport, walking and cycling. And so a lot of the focus of the scenarios is around improvements which would make that possible."
The first scenario - scenario A - would prioritise public transport, walking and cycling in the central city, adding high priority public transport lanes from the train station to the Basin Reserve, and removing peak-hour parking from Vivian St.
Scenario B includes those improvements, and adds an extra Mt Victoria Tunnel, a new layout at the Basin Reserve and mass transit, which could include light rail, between the train station, hospital and airport, at a cost of $700 - 900 million.
The third scenario adds a tunnel under Te Aro, which is expected to reduce traffic on Kent and Cambridge Terrace. This would take seven to 10 years to build, and cost $1.5 - 1.8 billion.
Scenario D takes all those elements and adds an extra Terrace tunnel, a fourth southbound lane on the State Highway 1 between Ngauranga and Aotea, and a plan to have fewer cars along the city's waterfront.
Mr Mein said the plans so far were high level, and detailed investigation and design work would come later.
Consultation on the proposals is now open, and closes on 15 December.