Driver training provider Drive & Survive has called for a rethink on speed limits, claiming fixed speed limits do not save lives.
The company has called for variable speed limits with lower than normal limits at peak time in dangerous areas, warning: "Speed on its own, can never kill."
Head of training, Mark Edwards, said there was too much obsession with speed limits when in many circumstances a driver could be within the legal speed limit but still be considered dangerous.
"That might mean deciding that 20mph in a 30mph zone, say near a school at three o'clock in the afternoon, is quite fast enough. In other words, one could be within the speed limit but still driving unsafely."
Edwards said the company was suggesting variable limits, with school opening and closing times forcing the limit down to 15mph near the schools and main road crossings.
For most of the day the speed limit would revert to 30mph, with it rising to 40mph between midnight and 6am.
On motorways, Drive & Survive has suggested 90mph in good weather conditions, with 50mph or 60mph limits imposed during poor visibility or heavy rain.