Traffic lights at Barton Highway roundabout operational

The planned upgrade aims to improve safety and ease peak hour traffic at the busy intersection of the Barton Highway, William Slim Drive and Gundaroo Drive.

Work on the intersection, originally due to start last June, didn't start until November and was stalled again last month due to wet weather.

Federal Infrastructure and Transport Minister Darren Chester said a shared path bridge was also open and there were more approach lanes, too.

"The upgrade will tackle congestion by significantly increasing the roundabout's traffic capacity, the new traffic signals will operate 24 hours a day and the approaches carrying the heaviest peak-period traffic will be prioritised according to the time of day," he said.

He said motorists would no longer need to identify gaps in the traffic flow and thus safety at the intersection, where on average more than 60 accidents occur a year, would be significantly improved.

ACT Transport Minister Meegan Fitzharris said the new traffic lights would be in a testing phase over next the few weeks to refine the most efficient operation and timing.

"An additional lane within the roundabout, as well as on each of its approaches, will also increase capacity and cater to the traffic growth generated from the developing Gungahlin region," she said.

Further minor works would continue until February on the William Slim Drive approach and on the third lane on the Barton Highway southbound approach to the intersection.