Clampdown on Drivers Flouting M4 Variable Speed Limits
Drivers who flout variable speed limits on a stretch of the M4 at Newport will face action as part of a clampdown.
The system, which aims to keep traffic moving between junctions 24 at Coldra and 28 at Tredegar Park, was introduced in 2011.
Economy and Infrastructure Secretary Ken Skates said speeding motorists will now face tougher enforcement action.
The warning comes as a safety campaign is launched on Monday, which aims to raise awareness of the speed limits.
They were brought in by the Welsh Government to reduce congestion and improve "safety and journey time reliability".
Mr Skates said: "Since its launch the scheme has helped to improve traffic flow and reduce the number of collisions along this stretch, with the majority of drivers adhering to the limits in place.
"However, a minority of drivers continue to flout the displayed limits and act as if the restrictions do not apply to them.
"It is these motorists we are primarily targeting with this awareness campaign and subsequent enforcement action."
The campaign is being led by GoSafe, Wales' Road Casualty Reduction Partnership.
There will be a grace period for drivers who exceed the limit with the number of speeding motorists highlighted on that stretch of motorway. Then, during the second phase of the clampdown, motorists will face action and they will receive a Notice of Intended Prosecution.
GoSafe Partnership Manager Chris Hume said the move would help to reduce casualties and save lives.
"Managing the speed of traffic through this busy section of the M4 motorway is vital," he said.