Opposition to a Basin Reserve flyover is mounting and Labour's Wellington MPs say the plan is "deeply flawed".
The New Zealand Transport Agency (NZTA) on Friday announced it was going ahead with a $90-million bridge just 20 metres north of the Basin Reserve.
It has rejected a cheaper option further north of the cricket ground and also tunnels, estimated to cost up to $260m.
Wellington Mayor Celia Wade-Brown says the decision is "disappointing" and she wants NZTA to ensure the flyover doesn't ruin the historic ground and the suburb of Mt Victoria.
NZTA Wellington state highways manager Rod James says a tunnel is impractical because the area was once a lagoon.
Labour's Wellington Central MP Grant Robertson and Rongotai's Annette King say the decision is an example of the government's piecemeal approach to transport issues in the city.
"The decision is deeply flawed... the construction of a large concrete flyover beside the Basin Reserve is the wrong approach," they said in a joint statement.
"There are alternatives that need to be revisited that will improve traffic flow without destroying the character of the area."
The MPs say NZTA hasn't listened to public concerns.
"The plan doesn't even include a second tunnel through Mt Victoria, which while apparently still on the agenda is so far off it isn't even worth putting in the plan," they said.
"This makes the proposal half-baked and it could actually lead to more traffic congestion."
The road around the cricket ground is effectively a large roundabout which clogs the state highway system.