A new network of tunnels, dedicated public transport routes, and slower inner-city speed limits could be the $2 billion ticket to reducing the congestion in central Wellington.
The city’s transport leaders have presented four transport "scenarios" for residents to have their say on over the next month.
The short list has taken Let’s Get Wellington Moving 18 months to complete, after the Basin Reserve Flyover was shot down by both an independent board of inquiry and the High Court in 2015.
The scenarios build on each other; starting with a basic package, and adding more changes from one scenario to the next.
The most basic option is also the cheapest at $150 to $200 million: reduce inner-city speed limits, and prioritise key streets for public transport, walking and cycling.
The next option, at $700 to $900 million, builds on the first and adds a second tunnel under Mt Victoria.
The third re-routes State Highway One into tunnels underneath the CBD, costing $1.5 to $1.8 billion.
And the fourth, includes all of the previous options plus a second Terrace tunnel. That would cost $1.9 to $2.3 billion.
A "public transport spine" would be protected in all but the first option. Such a spine could be used for future mass transit options such as larger buses or light rail according to demand.
Project leader Barry Mein said the scenarios would "encourage a shift in how people travel, a key factor in supporting a reduction in the city’s transport-related greenhouse emissions."
"It would also unlock potential regeneration along the public transport spine."
"Our work has shown we can’t solve Wellington’s transport problems by just building more roads. We don’t have the space," he said.
The scenarios also show some small flyovers could be built near the Basin Reserve.
Save the Basin’s Tim Jones said that felt "like a slap in the face".
"These plans will not get Wellington moving. The induced demand of a road-first approach will just make traffic chaos throughout the city worse. We need to create viable transport alternatives to reduce dependence on private cars, and make travel easier and safer for the people who really need to use the roads," Mr Jones said.
The most expensive option could take up to 1,000 cars off inner-city streets during the morning rush hour, cut public transport times from southern and eastern suburbs by a third, and make the drive between the airport and Johnsonville up to 20 per cent quicker, and 30 per cent faster on the way back.
The Regional Council chair Chris Laidlaw said there was "no one single solution and some sacrifices, including on-street parking, will be inevitable".
"We need a programme of work that will reduce the volume of private traffic entering the CBD, free up vitally needed space for public transport, and create more scope for walking and cycling in the central city," he said.
The city’s mayor Justin Lester described it as a once-in-a-generation opportunity and encouraged all to have their say.
The final shape of the changes would “come down to how much support we receive from the new government and the regional council,” he said.
"This is not a bill that the Wellington ratepayer will be footing alone."