The A4042 in both directions between Pontypool and the Court Farm roundabout will have one lane on the southbound carriageway closed all day every day until February 2025.
The northbound carriageway will also have some disruption, with narrow lanes being put in place for 24 hours a day until February next year.
The dual carriageway is undergoing essential repairs to the safety barrier and replacing the street lighting on the road.
The works are expected to be ongoing until Friday, February, 7 2025.
Traffic Wales South has advised that drivers should expect delays in the area with the narrow lanes and lane closure, particularly during rush hour.
They have also advised that drivers should allow for additional journey time for the next few months.
