The New Zealand Transport Agency has released proposals for road improvements for the link between the city and Wellington airport.
The proposals include two options for a flyover beside the historic cricket ground the Basin Reserve and a second tunnel under Mt Victoria.
NZTA central region director Jenny Chetwynd says the $500 million improvements are on a section of State Highway 1 that will support the city's expansion and economic growth.
"The Basin Reserve is a major bottleneck, where numerous streams of traffic from different directions compete to use a very constrained road space," Ms Chetwynd says.
"We've proposed a new bridge to separate traffic, which will help to free up road space for public transport priority measures and improve safety for pedestrians and cyclists who use this area."
The agency proposes widening Ruahine St and Wellington Rd to up to six lanes, requiring about one and a half hectares of land from the town belt and about 20 houses.
There will be a two-month period of public consultation on the proposals.
Calls for rethink
The Mayor of Wellington and the MP for Wellington Central are calling on the Transport Agency to reconsider the option of a tunnel rather than a flyover beside the Basin Reserve.
The mayor, Celia Wade-Brown, says a flyover would spoil the cityscape.
MP Grant Robertson says the agency should have included in the public consultation a tunnel beside the Basin and under the neighbouring War Memorial Park currently being constructed on Buckle St.
The agency says a tunnel was investigated but would have been significantly more expensive than a flyover.
Endorsed by Transport Minister
A city councillor, Iona Pannett, says the projected economic returns do not justify the work going ahead, and she predicts there will be widespread public opposition.
But the proposals have the endorsement of Transport Minister Steven Joyce, who says road improvements in Wellington city are badly needed.
Mr Joyce says the improvements to State Highway 1 between the city centre and the airport match the Government's view that the route from Levin to the airport is a road of national significance.
He says it is important for the whole country that there be real economic growth and development in the lower North Island and the road improvement plan will help that happen.