Average Speed cameras on the M4 will start issuing fines this month, more than a year after they were installed.
The cameras cover the 50mph stretch of road around Newport, but drivers have escaped prosecution up to now.
The Welsh government has set a date for the cameras to start issuing fines after what it called “a significant upgrade” of the IT system.
From 17 November, drivers caught speeding between junctions 24 and 28 of the M4 will be fined.
The average speed limit of 50mph was introduced last year to tackle congestion.
The Welsh government also said that cameras and enforcement at all other 50mph zones were now fully operational.