Average speed cameras on the A9 are already proving their worth by reducing the number of serious speeding incidents, according to the Scottish Government.
A government spokesman said: “The aim of the A9 average speed camera system is to improve road safety and to save lives as a result.
“They are effective in helping save lives and this is backed up by the facts – before and after studies of all other average speed camera sites in the UK show a reduction in accidents.
“Instances of excessive speeding on the A9 have dropped from around one in 10 to less than one in 700 since the cameras were installed and there has been no significant effect on journey times as a result of more people driving within the speed limit.
“The A9 average speed cameras are not being used in isolation, they are part of package of measures to make the A9 safer, including substantial investment in engineering improvements, such as improved lighting and signing, as well as education campaigns.”
He added that the government was “making good headway” with the dualling of the A9 between Inverness and Perth. The first of the dualling schemes, at Kincraig, has been brought forward by around six months, with construction expected to begin next summer.