When is a pothole in the road not a pothole? When it is less than 4cm deep, according to new guidelines that have been adopted by cash-strapped councils across Britain.

The councils are this weekend accused of contributing to the “chronic disrepair” of UK roads by redefining the size of potholes that they are obliged to fill.

More than 20 local authorities are cutting road maintenance bills by refusing to repair potholes less than 4cm deep. Some councils have doubled the size of “actionable” potholes in recent years.

The revelation comes ahead of a comprehensive survey of Britain’s roads, which will this week reveal that local authorities are facing a shortfall of more than £1 billion as they attempt to fill in 1m potholes a year.

The report, by the Asphalt Industry Alliance, will blame utility companies for digging more than 2m trenches a year in Britain’s highways, the equivalent of one for every 200 yards of local authority road.

While road maintenance budgets are being squeezed, councils are spending more than £100m a year on traffic calming measures such as speed humps, cushions and chicanes. Emergency services have raised concerns that the measures are putting lives at risk by delaying response times.

Motoring and cycling groups have warned local authorities that redefining potholes is “shortsighted” and will lead to more accidents and a surge in compensation claims. John Meudell, vice-president of CTC, the national cyclists’ network, said: “It’s an outrageous sleight of hand. They are putting the safety of pedestrians, cyclists and motorists at serious risk.

“These holes are pretty deep, easily enough for somebody to twist their ankle or to go flying off their bike. Ultimately it’s counter-productive and will come back to haunt them because more people will end up suing them. It’s perverse.”

Essex council is among those struggling with a shrinking road maintenance budget, which this year fell by 10% to £46m. From April it will increase the size of “actionable” potholes from 2cm to 5cm deep.

Norman Hume, Conservative cabinet member for highways and transportation at the council, admitted that the move was about saving money. He said the average pothole cost more than £200 to fill in on its own, but the price was nearer £20 if it was done as part of general resurfacing, which is carried out every 15 to 20 years.

“We want more bang for our buck in terms of improving our roads. By focusing our efforts on larger potholes we are improving safety. You wouldn’t even call 2cm, our current definition, a hole and it would not be regarded by our engineers as unsafe,” he said.

The move prompted local Liberal Democrats to launch a competition to find Essex’s worst potholes. The winner, Kings Road in Chelmsford, is pitted with more than a dozen potholes measuring up to 5cm deep and 25cm across.

Heather Searle, 42, a teaching assistant at Kings Road primary school, said: “The road is an absolute disgrace. It’s putting everyone at risk, from mothers with pushchairs to children on bikes. The whole street is more or less one continuous pothole, but the council don’t seem to be doing anything about it. A hole in the ground is a hole in the ground. If anyone can trip over it then it’s dangerous.”

Lancashire and Surrey have also doubled the depth of their actionable potholes from 2cm to 4cm. In Surrey the council changed its policy in December 2004 and has seen a subsequent drop in repairs. Last year it repaired 16,674 potholes, compared with 19,400 in 2005-6.

Roger Smith, 49, a building society assistant manager, is pursuing a claim against the council after being thrown from his bike when he hit a pothole in Epsom in January last year. He lost a tooth and needed extensive dental surgery.

The Sunday Times found 14 councils that define a pothole as more than 4cm and a further seven councils whose definition is over 5cm, including Cheshire, Kent and Bedfordshire. Many are following recent government guidance which advises councils to repair only potholes of more than 4cm within 24 hours.

Edmund King, president of the AA, the motoring organisation, said: “Councils may think they’ll make big savings but in the long term it will cost them, motorists and cyclists a lot more. It’s an own goal and hides the true state of Britain’s roads.”

The government is planning to give councils powers to fine gas, water and electricity companies up to £5,000 for working without a permit or £2,000 for failing to finish work on time.

David Sparks, transport spokesman for the Local Government Association, said: “For too long utilities have been able to dig holes in the road with little consideration to the disruption this causes. From now on councils will be able to ban works until a specified date, to stop the same streets being constantly dug up, saving the council taxpayer and helping to get motorists safely through the day.”

Additional reporting: Nicky Trup, Nicky Evans

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