Newport M4 variable speed limit prosecutions to start
Motorists who get caught speeding on the variable limit section of the M4 in Newport now face being prosecuted.
The system was introduced on an eight-mile (13km) stretch of motorway in 2011.
In July, it emerged no speeding drivers had been prosecuted during that time.
For 14 days from Monday, advisory notes will be sent to people caught speeding - after that, prosecution notices will be sent to those flouting the limits.
The variable speed limit covers the stretch of road from junction 24 (Coldra) to junction 28 (Tredegar Park).
Infrastructure Secretary Ken Skates said: "Since its launch the scheme has helped 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."
Enforcement of the variable speed limit has been passed to GoSafe.
The organisation's partnership manager Chris Hume said: "Where we have to, we will deal with those drivers formally through the prosecution process, but we are trying to ensure that anyone who may have become complacent over the variable limits clearly understands the risk they will be taking and the legal consequences."