Motorists' lives have been put at risk by thieves who have ripped down dozens of chevrons on sharp bends in Staffordshire.
Police said there had been a spate of thefts of the black and white signs in recent weeks.
A Staffordshire Police spokesman said it was possible they were being stolen for scrap, either by individuals or an organised gang.
Although there have always been occasional thefts of chevrons, often as a prank, it is thought to be the first time they have been targeted in such numbers.
John Wakefield, Staffordshire County Council's cabinet member for development services, said: "There are thousands of these signs throughout Staffordshire. It has become clear in the last couple of weeks that a significant number have been stolen.
"Our inspectors are now carrying out an urgent survey in an attempt to pinpoint all the locations where they have gone and arrange for their replacement."
Sites where thefts have happened include the A518 at Chartley and Loxley B5066 Hopton, Hilderstone and Sandon Bank, Meaford Road, Barlaston and the A51 at Hatton.
No accidents have been reported as a result of the thefts but the bill to the local authority has already topped £10,000.
Coun Wakefield said it would be obvious to scrap dealers that the chevrons were stolen.
"These thefts are callous in the extreme," he said. "Chevron signs warn motorists they are approaching sharp bends and are life-savers, particularly when drivers are travelling along a stretch of road they're unfamiliar with.
"We will now have to fund replacements from our existing highways budget. We are investigating the possibility of replacements made from plastic that has no scrap value, even though they may not be as durable."
* Anyone with information about the thefts can contact Staffordshire Police on 08453 20 2010 or Crimestoppers anonymously on 0800 555 111.
