Average speed cameras on the A90 north of Dundee will go live today.
The devices have been installed at locations on both sides of the carriageway on the 51.5 mile stretch of road between the city and Stonehaven.
The controversial £2 million project has seen the installation of 15 pairs of cameras in a bid to reduce the number of deaths on the road, which connects Dundee and Aberdeen.
More than 60% of drivers speed on the A90 — with one in five hitting more than 80mph.
Scottish transport minister Humza Yousaf said: “We know that the A90 trunk road has the highest rate of collisions in Scotland.
“More than three in every five vehicles travelling between Dundee and Stonehaven are speeding.
“This system will help reduce that rate and save lives.
“The positive impact average speed camera systems have in improving road safety has been evidenced from other areas in Scotland.
“We remain committed through Scotland’s Road Safety Framework to 2020 to making our roads safer and we are working towards an ultimate vision of zero fatalities and a reduced number of serious injuries on our roads.
“If you use the A90, remember that the average speed cameras will be activated.”
Police Scotland, road safety charities and business groups all welcomed the decision to install average speed cameras when it was announced in March.
Transport Scotland revealed there have been 60 serious or fatal collisions on the road in the last five years.
But critics, including the Alliance of British Drivers, have argued that the system is simply about making money rather than improving safety.
The A90 cameras will be the third such scheme in Scotland, following the introduction of average speed stretches on the A77 in Ayrshire in 2005 and the A9 between Dunblane and Inverness in 2014.