Drivers who ignore lane closures on smart motorways in England will face automatic £100 fines and penalty points on their licence, under new laws.
Hundreds of miles of road have been converted into smart motorways, meaning the hard shoulder is used as either a permanent or part-time traffic lane.
Red X signs are then used to shut lanes due to accidents or stranded cars.
But Highways England said thousands of motorists ignore the warnings, putting other drivers at “real risk”.
It is already illegal to drive in a lane marked with a red X, but police officers previously had to catch drivers in the act.
Under new Home Office legislation, police will be given the power to penalise drivers captured on traffic cameras ignoring the signs.
In addition to a fine, offenders will be given three penalty points.
Highways England said more than 180,000 warning letters had been sent out since December 2016.
It said the new laws were due to come into force in “late summer”.
AA president Edmund King said the use of cameras to catch offenders was a “welcome measure to improve safety”.
“Red Xs are put up to warn of an obstruction, so drivers must get out of the lane when they see them,” he continued.
He said members of his motoring association had experienced several incidents recently where their cars were hit on a smart motorway.