A LORRY which flipped on to its side may have been hit by a bizarre phenomenon causing large lorries to tip over at low speeds, police have said.

The vehicle toppled over on to its side while it was driven across the roundabout between the A19 and A64 near the McArthurGlen designer outlet at York yesterday.

The driver was pulled clear of the vehicle through a sunroof, according to eyewitnesses.

The cabin of the lorry suffered a smashed windscreen, buckled roof and other damage.

There were no other vehicles involved.

"It looks like it might have been a low-speed rollover," said road policing group constable John Stewart.

"In circumstances such as these you see an articulated lorry tipping over on to its side while travelling at reasonably low speeds."

PC Tony Smalley said: "Everybody sees these and assumes the driver has been driving like a maniac,but they often suffer from slow roll, and it doesn't necessarily mean they have been driving badly.

"In fact, according to the witnesses this driver wasn't driving badly, and the weather conditions were fine."

An ambulance spokeswoman said the driver, believed to be from the Tyneside area, was taken to York Hospital.

PC Stewart said the driver suffered a suspected broken collar bone and cuts and bruises.

Road policing group sergeant Nigel Atkinson said the phenomenon of slow speed rollover or roll resonance was well known.

"It's more commonly associated with fluid loads, such as in tankers; the fluid shifts its weight according to the bend or the camber of the road.

"It moves the centre of gravity of the load and sends it tipping over on to its side in what seems like slow motion, happening invariably at low speeds."

He said: "Drivers need to be aware of the capabilities of the trailer as they are obviously carrying heavy loads, and need to know how to deal with them.

"But although we do see these incidents, the number of them is quite insignificant compared to the number of lorries on roundabouts every day.

"And there is of course a potential danger with every vehicle on the road."

Updated: 10:54 Friday, September 19, 2003