A SINKHOLE has opened up in a residential street in Ferndown - for the second time in 18 months.

Residents of Coppice Avenue say major work needs to be done to the road after the hole was spotted by a dog-walker on Saturday evening.

Although the hole in the carriageway is just 30 inches across, the sinkhole covers a large area beneath the surface of the road.

Jim Savage called police after spotting the depression while walking rescue dog Dudley.

Mr Savage, a former civil engineer, said: "I was just out on a walk when I spotted it in the middle of the road.

"Cars were going past and missing it by a tyre. I realised straight away that it was a sinkhole and called for police."

He said there are dips in the road the length of Coppice Avenue.

"The road suddenly drops in places," he said.

"There's obviously something going on underneath."

William Filer, who lives with wife Miriam near the sinkhole, said: "About 18 months ago another sinkhole opened up just a bit further along the road.

"There are plenty of dips along the surface, so there does seem to be a problem.

"There's obviously quite a cavity underneath the road."

Bollards to prevent motorists from driving over the sinkhole have been put in place by council engineers. A team of workers are expected to dig up the road in the coming days.

One resident said the sinkhole is "extremely deep".

"It's quite worrying to think the road keeps opening up under our feet," she said.

"I do wonder if it's just the road or if houses are going to be affected too."

Sinkholes are caused by some form of collapse in the surface layer of the ground.

They may form gradually or suddenly.

Natural sinkholes - as opposed to manmade tunnel or cave collapses - occur when acidic rainwater seeps down through surface soil and sediment, eventually reaching a soluble bedrock such as sandstone or chalk.

The water gradually dissolves small parts of the rock, enlarging its natural fissures and joints and creating cavities beneath.