A proposed rapid bus route through central Wellington is being reviewed, causing concern among some local councillors.

It has been chosen as the best way forward for Wellington's public transport woes, and new routes designed around the bus rapid transit scheme through the city are agreed and ready to go.

But now the group charged with getting Wellington moving wants to look at the idea again.

That has infuriated regional councillor Paul Swain, who has blasted the plan for a review as "totally inappropriate".

LIGHT RAIL TRANSIT ASSOCIATION/SUPPLIED An engineering firm has been asked to check whether the proposed route could be future-proofed for light rail.

"This horse has bolted. We've decided on the routes and [the new contracts have] gone to tender," Swain said.

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"It's totally inappropriate to tell people we might have another look at this."

FAIRFAX NZ Greater Wellington regional councillor Paul Swain says the intended review is "totally inappropriate".

The Let's Get Wellington Moving working group, tasked with solving the capital's congestion issues between the airport and Ngauranga Gorge, told Greater Wellington regional councillors on Tuesday that it planned to review the proposed rapid bus route, between the railway station and the hospital.

The council plans to introduce a new bus network next year, designed around the proposed route, having recently announced Masterton-based Tranzit as the preferred bidder for most of the city's services.

The new network will be made up of 16 "units", with bus companies operating in those groups rather than on individual routes.

SUPPLIED Fellow regional councillor Ian McKinnon also had some concerns about the review.

The rapid bus route would runs from Wellington Railway Station along Lambton Quay, Willis St, Manners St, Courtenay Pl, Kent/Cambridge Terrace and Adelaide Rd to Wellington Regional Hospital in Newtown.

Let's Get Wellington Moving programme director Barry Mein told councillors on the sustainable transport committee that the group had recruited engineering and design firm Parsons Brinckerhoff to review the findings of a 2013 Public Transport Spine Study to check they were still "fit for purpose".

The firm would also reassess the suitability of the rapid bus route, and whether the same route could be future-proofed for light rail.

Swain questioned what the implications would be for the council's contracts if the route was found not to be appropriate, but Mein said the council's bus contracts were not in jeopardy.

"I would be very surprised if it had any impact on your contracts at all."

There was not a lot of disagreement on the proposed route, and the study's main focus would be on its suitability for light rail conversion, Mein said.

Councillor Ian McKinnon shared Swain's concerns, asking if future-proofing the route for light rail could affect implementation of the new bus network, which had been agreed upon.

Mein responded: "We're not saying you don't go ahead, and we're certainly not rethinking the work that you're already committed to and the process you're committed to with the changes to the buses.

"But there does need to be, regardless of how this work that we've recently commissioned comes out, something that's done to improve a lot of the buses that are working through the central part of the city, because they are slow."