A Tesco Car Insurance survey of 1660 motorists uncovered that of all road signs tested, only the speed camera warning was universally recognized -- even though it has only been in use since cameras were introduced in 1992. Half of respondents, for example, thought the sign for "no buses" meant the opposite -- buses only. Ten percent thought the "national speed limit applies" sign meant the maximum speed is 70 MPH, even though that speed only applies on divided highways.

The Institute of Advanced Motorists (IAM), the UK's leading organization for improving driving standards, suggests that the government should stop capitalizing on motorist confusion. It asked NOP to survey 550 drivers nationwide and found nearly nine out of ten drivers want the speed camera signs to also indicate the current speed limit. Moreover, eight out of ten want electronic speed warning signs that warn motorists of their current speed to be placed ahead of camera sites.

"The thinking behind the speed limits on many roads simply isn't clear to many drivers, causing widespread frustration and disobedience," the IAM's John Maxwell said. "We need a national review so that speed limits are set at levels which are sensible, understandable and acceptable."