Traffic going through the heart of Aberdeen has halved since the opening of the AWPR.
Around 50% of drivers who would have gone the city centre have diverted on to the new bypass since February, Scottish Government figures show.
The 36-mile road from Stonehaven to Ellon – around the western edge of Aberdeen – fully opened three months ago.
The average morning commute from Stonehaven to Dyce took 47 minutes before the new road opened, with the same drive in the evening taking 42 minutes.
Both journeys now take 18 minutes on the AWPR, Transport Scotland said.
Speaking in Aberdeen this morning, First Minister Nicola Sturgeon said: “The AWPR has brought huge benefits to the north-east with these initial findings showing both journey times and congestion have improved over the last few months.
“As a result of the AWPR, vehicles that were previously sitting in nose-to-tail traffic and causing pollution have now shifted, leading to lower emissions in the city.”
Chief executive of Aberdeen & Grampian Chamber of Commerce Russell Borthwick said: “We now have our Aberdeen Western Peripheral Route and it is already enhancing connectivity across the entire region, transforming journey times, reducing business costs and improving productivity and quality of life.”