Newport M4 speed limits 'not intended for prosecuting drivers'
No drivers have been prosecuted under a variable speed limit camera system set up to reduce M4 congestion in Newport five years ago, it has emerged.
The Welsh Government has launched a campaign warning of action to come against drivers who break the limits.
But its Traffic Wales arm said it had never intended to use the system to prosecute drivers during an "initial scoping period".
It said the fixed cameras on the route were used to monitor traffic flow.
The system, which aims to keep traffic moving between junctions 24 at the Coldra and 28 at Tredegar Park, was introduced in 2011.
It is made up of electronic signs which display speed limits, together with traditional road signs indicating that enforcement cameras are in place.
A spokeswoman for Traffic Wales, which is part of Welsh Government, said: "The variable speed limits currently in place along this stretch of the M4 are not optional and are legally binding, just like imposed speed limits on any other stretch of road in Wales."
She said: "To date, the aim of the fixed speed cameras along this stretch has been to monitor traffic flows so we could gain a better understanding of traffic movements along this busy stretch of M4 and establish how many motorists were adhering to the then newly-introduced variable speed limits.
"It was never our intention to use these cameras to prosecute drivers during this initial scoping period - simply to gain a better understanding of how effective the Variable Speed Limits were at improving safety and traffic flows before and after installation."
Chris Hume, manager of the GoSafe police and council speed camera enforcement partnership, confirmed there had been no prosecutions since the system was set up.
"Up until this point there has been no police action for motorists exceeding the speed limit," he said of the camera system on the stretch of M4 concerned.
On Monday, Economy and Infrastructure Secretary Ken Skates announced that speeding motorists would face enforcement action.
"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," he said.
"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."
Initially, there will be a grace period for drivers who exceed the limit, amid publicity for the number of speeding motorists identified on that stretch of motorway.
Then, during the second phase of the clampdown, motorists will receive a Notice of Intended Prosecution.
Mr 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.