SPEEDS have fallen by a minuscule amount since County Hall paid £300,000 to make Oxford a 20mph city.

New figures show drivers have slowed down by an average of 0.9mph since the new limit was introduced.

Speed surveys carried out on 65 roads roads covered by the new 20mph zones show in the first 12 months speeds fell to an average of 21.1mph, compared to 22mph in the year before the scheme was introduced.

Almost all Oxford’s residential roads and some of the city’s arterial routes became 20mph zones in September 2009.

Last night, critics said the drop in speed was not significant enough to warrant the investment.

However, Oxfordshire County Council said national studies showed even a 1mph average reduction can lead to a five per cent reduction in casualties.

The accident rate has fallen since the limit was introduced. Between September 2008 and August 2009 there were 166 accidents across the county, falling to 159 in the same period the following year.

Mark McArthur Christie, chairman of the Oxford group of the Institute of Advanced Motorists, said the drop in speed was not worth the investment.

He said: “They spent nearly £300,000 to achieve a fall in speed of 1mph.

“Oxford city does not have a problem with speeding traffic.

“People are in excess of the legal limit, but that doesn’t mean they are driving unsafely.”

Thames Valley Police is preparing to turn Oxfordshire’s speed cameras back on in April after the council decommissioned them on August 1 last year after funding was withdrawn from the Thames Valley Safer Roads Partnership.

In Portsmouth, where the first city-wide 20mph limit was introduced in 2008, the Department for Transport found the average speed went down the same amount, 0.9mph, in the first year.

Mark Strange, driving instructor of 18 years, said: “It has not made a big difference. I was not against it, but spending £300,000 is a waste of money.”

He said on some main roads the limit had added to congestion as drivers slowed down.

Thames Valley Police has still not fined any motorists for breaking the 20mph limit.

The Rev Andrew Bevan lives in Newman Road, Littlemore, where speeds have gone up by almost 7mph eastbound and 5mph westbound.

He said: “I think the 20mph limit means people actually stick to 30mph instead of going at 40mph like they used to.

“I am surprised it has gone up, but it depends on how the data was collected.”

Blackbird Leys Parish Council chairman Gordon Roper said: “I can’t say the limit has really worked. Until they start prosecuting, people won’t stick to it.”

Councillor Rodney Rose, cabinet member for transport, called for more enforcement, adding: “The fact the speed limit has come down and the accident data has improved shows it has been effective.”

County Hall spokesman Marcus Mabberley said it was pleasing the data showed a reduction in speeds and accident rates, but said the data should be examined over several years before conclusions were formed.

Chief Inspector Gill Wootton, Deputy Head of Roads Policing, said the limit should be self-enforcing. She added: “Speed enforcement will only be used when other options have been exhausted. Any reduction in speed in the relevant areas should be celebrated as this represents a reduction in the risk to local road users.”