A £10 million project to “untangle” traffic at the heart of Brighton and Hove has moved a step closer.

Councillors agreed to updated proposals to overhaul Valley Gardens with a business case now being sent to the Coast to Capital Local Enterprise Partnership (LEP) to approve £8 million of funding.

A decision on that funding is expected in November and residents could see the changes by summer 2017.

The project will see private vehicles restricted to two lanes running from The Level down to the Palace Pier while the current section running between Pavilion Gardens and London Road will become a bus lane.

Councillors were warned that if they could not agree the business case at Brighton and Hove City Council’s environment, transport and sustainability committee last night, the window for funding might close for the foreseeable future.

Opposition councillors have raised concerns that the economic benefits for the transport overhaul have been overstated to impress LEP bosses.

Claims that the overhaul will “unlock the potential” and attract investment into other sites such as the Brighton Centre and Black Rock were described as “tenuous”.

The council claims the changes will bring financial benefits of at least £39 million over 20 years, including millions from health benefits of more cycling, walking and fewer car crash victims.

To meet the criteria, the project has to prove financial benefits at least double the level of investment.

Labour councillors said a cut in congestion and pollution in other areas of the city such as the Clock Tower or the seafront were needed rather than “cosmetic” improvements to Valley Gardens.

The overhaul could also see the end of a city landmark with the future of the Mazda fountain undecided.

The Valley Garden plans will mean the carriageway to the west will become a bus lane, known as The Park Road, with private vehicles restricted to the two-lane east carriage known as The Avenue.

Traffic from Church Street and North Road will filter across the bus lane into The Avenue.

The changes include a new 700m north to south cycle lane along The Avenue. Cyclists will share The Park Road with buses.

An extra 265 new elm trees will be included.

As well as £8 million from Coast to Capital, Brighton and Hove City Council will contribute £500,000 to the project.

Labour councillor Gill Mitchell said the business case was “overblown” and that other areas of the city such as the Clock Tower and the seafront were much more in need of investment.

She added: “I was really surprised when I read this report at the lack of detail on the impact of this scheme on other areas.

“The whole thing has got to work in practice and we are not 100% satisfied that it will.”

Green committee member Ian Davey said: “This is once in a generation opportunity to transform this space in the heart of the city from a mismatch of tarmac going into different directions to a city centre park with a transport system that works much better than it does now.”

Conservative committee member Geoffrey Theobald said that if he had the choice he would put the £8 million towards the seafront but that choice wasn't open to him and the money would be welcome in transforming a section of road he said all agreed was “a mess”.

Chairman Pete West confirmed that the money was not transferable and the city would lose the £8 million funding if the proposals weren't accepted.