Up to one in 10 drivers are at risk of being fined for ignoring lane closure signs on motorways, according to new figures.
National Highways said the percentage of drivers who obey the red X signs is “more than 90%”, indicating that almost 10% do not.
From September 2022, all police forces are able to use enforcement cameras to prosecute drivers who illegally run through a red X or enter a lane longer than one.
This can result in a fine of up to £100 and three penalty points, or more severe penalties and a court appearance in some cases.
Surrey Police was one of the first forces to prosecute offenders caught on camera in November 2019.
New figures show they have issued 9,427 Notices of Intended Prosecution since then.
Some 4,926 recipients completed a safety awareness course, while others chose other options such as paying a fixed penalty or hearing the case in court.
The road policing unit covering Bedfordshire, Cambridgeshire and Hertfordshire said almost 300 vehicles were seen breaching a red X displayed on the M25 near Junction 20 on one day in December 2018 and emergency roadworks were carried out following an accident.
One of the guilty drivers took the case to court, where he was ordered to pay a fine and costs of almost £1,000.
He also received three penalty points.
Obeying red X signs is vital to smart motorway safety.
National Highways staff move the lane closed signs when vehicles are found stopped in live lanes to avoid rear-end collisions and to assist and protect the emergency services.
Chief Constable Jo Shiner, head of the National Police Chiefs Council for road policing, said: “Red X signs are in place on the motorway for your safety and the safety of others.
“Sadly, there are too many cases where drivers fail to obey the red X signal and put others at incredible risk by driving in a closed lane.
“This is unacceptable and drivers who do this must understand that they are subject to prosecution.”
National Highways traffic officer Dave Harford said: “We don’t take the decision to close lanes lightly, but when we do, motorists must comply with the closure.
“A red X is there for the safety of everyone on the road – including people in distress, traffic officers, emergency and recovery services assisting them, and all other road users.”
AA president Edmund King said: “With more than a third (38%) of smart motorway failures occurring on live lanes, it is vital that all drivers avoid red X lanes as soon as possible, as the unknown you know what the danger might be. lie ahead.”
Simon Williams, RAC’s road safety spokesman, described the proportion of drivers using closed lanes as “very concerning”.
He said: “We have been concerned for some time that the red Xs displayed on the side of the road are not nearly as obvious as those on bridges directly above each lane.
“We fear this may be a factor in some of the non-compliance.”