Testing on M1 variable speed limits tonight
Testing during weekdays is starting four months earlier than planned, the agency said, meaning that road users will benefit in time for the Christmas holiday getaway.
At busy times, the overhead electronic signals above the motorway will display variable mandatory speed limits within red rings, and overhead message signs will indicate when drivers can use the hard shoulder as an extra lane.
These measures will allow a managed motorway to operate along the whole 15 mile stretch - from junctions 10 to 13.
This phase of testing is to ensure the systems and technologies are working correctly and follows two successful periods of testing earlier in the month.