Highways England has announced a review of the way variable speed limits are set on smart motorways.
It comes after an investigation by The Times which revealed a tenfold increase in the number of motorists being fined while driving below 70mph.
Data obtained under the Freedom of Information Act showed that 72,348 people were fined on motorways with variable speed limits last year -- almost double the number a year earlier and a tenfold rise in five years.
In response, Highways England acknowledged that lower speed limits were not always set correctly and said it would carry out a "comprehensive" review of variable limits.
Highways England chief executive Jim O'Sullivan told the newspaper that 40, 50 or 60mph limits are set before congestion builds up, using predictions about traffic levels. However, he admitted that this leads to "dissatisfaction" among some drivers when the expected build-up fails to materialise, forcing them to drive slowly along free-flowing roads.
"Nobody has a perfect product and there is some room for improvement on how those limits are set," O'Sullivan said.
But he pointed out that the lower speed limit has to be imposed before the congestion appears: "If you don't set the limit before, there is no point having the speed limits."
AA president Edmund King said the investigation "begs the question of how many thousands of motorists have been caught out when they shouldn't have been; when they were fined on roads with limits that were artificially set too low."
King said the AA had previously raised the issue of inappropriate variable speed limits with Highways England.
"We have too many members saying they're driving down an absolutely open road with 50 or 60mph speed limits on the overhead gantries," he added.
A spokesman for Highways England said in a statement: "We want to ensure that what drivers see also feels relevant to the traffic conditions, so we've improved the way we set message signs and signals on smart motorways and have started a comprehensive review of how variable speed limits are set, including the amount of time they are visible to drivers.
"Our initial analysis of actual traffic flows and changing the algorithms has already reduced the amount of time variable speed limits are on by 200 hours per week across the network."
What do you think about variable speed limits on the motorway? Do they improve traffic flow?