Most of the city is en route to become a 20mph zone – despite no evidence proving the scheme’s initial phase has worked.

Just four months after the limits were introduced in the city centre, Brighton and Hove City Council is due to unveil plans to widen the scheme.

Town hall bosses believe the next phase, which will be almost twice as large as originally planned, will improve road safety and reduce air pollution.

This is despite local authority officers admitting to councillors they will not have any evidence on whether the limits are working for at least another year.

Ian Davey, the council’s transport spokesman, said: “The council is committed to making the roads in the city safer for everyone and we know reducing traffic speeds to 20mph in residential streets is a practical and popular way we can do this.”

Coun Davey said the local authority wanted to listen to all views, adding the general feedback so far had been “very positive”.

But Elliott Raggio, director of On Tap, a Hove-based firm which provides plumbers and handymen, said: “It’s ludicrous. Phase two should be called the ‘wasting more taxpayers’ money phase’.

“If this were a business, spending money on a second phase without checking if phase one were a success it would be classed as a gamble and possibly business suicide.

“They are slowing down everyone in the city which is slowing down the city’s economy.”

Restrictions on more than 500 streets were introduced in the city centre area, from Sackville Road, Hove in the west, to Freshfield Road, Brighton, in the east, in April.

Originally phase two was to include Kemp Town, Moulsecoomb and Bevendean, as well as parts of Portslade, Hangleton and West Hove.

But it has now been expanded to include other areas, such as Westdene, Withdean, Hollingbury and Patcham.

If approved, the only areas not included within the zone will be Saltdean, Rottingdean, Woodingdean, north Portslade and parts of Hangleton.

The Argus:

As with phase one, main roads, such as Old Shoreham Road, London Road and Ditchling Road, will be excluded from the restrictions and remain 30mph.

About £1.5 million was set aside for the whole 20mph project and the first phase was due to cost £500,000.

But The Argus understands it only cost £300,000.

Opposition councillors claim the excess is being spent on including more areas in phase two.

But Coun Davey said the wider zone was due to requests from communities.

A consultation on the scheme will start in the coming weeks with affected residents receiving information through the post.

A final decision will be taken by the council’s transport and environment committee in November.

Labour councillor Gill Mitchell said she would look at the consultation result but was concerned there had been no evaluation of whether phase one had worked.

She added: “I’m sure there are a number of areas where residents would like their neighbourhoods to be calmed but is it enough to offer them a city-wide 20mph limit that’s not properly enforced.”

Conservative councillor Graham Cox said he supported more limits but questioned the cost of the consultation.

Coun Cox said: “As I understand it, these proposals don’t include any roads where the average speed is currently above 24mph which does rather beg the question of what this is all supposed to be achieving.”

Mark Strong, who is a member of the city’s transport partnership, said: “I fully support the extension into less densely populated areas where speeds are generally higher than in the city centre and hence the risk to pedestrians and cyclists is higher.

“However the council will need to do more work on promoting these benefits to local communities.”

Martin Harris, of Brighton and Hove Bus Company, said: “We supported phase one for 20mph in the city centre and are in discussion with the council on ways in which the council's objectives can be extended whilst preserving the attractiveness and reliability of the bus network.”