The first section of the £745 million Aberdeen western peripheral route has opened to drivers.
The key bypass section includes a new roundabout at Craibstone junction and a replacement roundabout with traffic lights at the Inverurie/Dyce Drive junction.
The roundabout at Craibstone junction will connect with a new road to the airport.
Work on the scheme began in February 2015 and is set to run until winter next year.
At 28 miles long, it will bring a dozen new junctions, 14 miles of slip roads and two new river crossings.
The bypass is aimed at improving travel in and around Aberdeen and the north east of Scotland as well as taking traffic away from the city.
Economic forecasts predict it will boost investment by providing a fast-link for businesses and freight from the north east to markets further south.
It has also been calculated that reduced costs for businesses will be worth more than £6 billion to the north east and could lead to around 14,000 jobs over the next three decades.
Keith Brown, the Scottish government minister responsible for transport infrastructure, said: “The north east economy needs every stimulus that can be provided and our investment in this project is expected to bring in an additional £6 billion to the north-east economy and create around 14,000 jobs over the next 30 years.
“We can look forward to the full benefits of these works starting to be realised when the road opens in winter 2017.”
The scheme was given approval in 2009 after a four-month public inquiry and despite many local objections. It was then delayed by legal action.
The campaign group Road Sense claimed the route selection process was flawed. In October 2012, the UK Supreme Court dismissed the third challenge by William Walton, the group’s chairman.
Speaking after the judgement, Dr Dan Barlow, WWF Scotland’s head of policy, said that the budget would be “much better spent on improving walking, cycling and public transport around the north east, helping deal with chronic air pollution problems as well as reducing climate change emissions.”