Traffic travelling on the northern section of Majura Parkway switched lanes on Wednesday afternoon and the change will remain in place until the completion of that part of the road upgrade in the next four to six weeks.
Roads ACT director Tony Gill said the switchover between the Federal Highway and Tambreet Street was to be completed by 4pm.
"Westbound traffic travelling towards the Federal Highway and southbound traffic from the Federal Highway will be moved onto the left lane of Majura Parkway's southbound carriageway," he said.
"Traffic will remain in a single lane in both directions as the right lanes of the carriageway remain closed for finishing road works.
"Traffic controllers will be on location to maintain steady traffic movements during the transition."
A number of traffic diversions will be put in place as a result of the lane switch.
At Mount Majura Vineyard, southbound cars will be directed to exit left towards Majura Road and use Mount Majura Road, the bridge over the Majura Parkway connecting Majura Road to the vineyard.
At the Canberra Gun Club, northbound traffic will be directed to the U-turn bay, located near the Federal Highway on ramp. Cars will then be diverted south via the Majura Parkway, exiting at the off ramp to Hector Macintosh Grove.
At Captain Kilowatt, traffic will be directed to the Majura Road access road via the roundabout at Tambreet Street or the Majura Road exit lane.