Speeding on parts of the A9 has doubled after being significantly cut by average speed cameras, official figures showed today.
Up to one in six drivers broke the speed limit in March compared to one in 12 after the cameras went live in October 2014.
The cameras cut speeding from a peak of around 40 per cent of drivers to 5 per cent between Dunblane and Inverness.
However, the proportion of motorists breaking the 70mph limit at Broxden in Perth has gone up from 7.45 per cent in December 2014 to 16.42 per cent in March.
Those driving at 80-90mph there increased from 0.16 per cent to 0.51 per cent - or from one in 600 to one in 200 vehicles.
Motorists breaking the 60mph limit at Killiecrankie increased from 6.57 per cent to 11.88 per cent.
Those doing 70-80mph went up from 0.26 per cent to 0.6 per cent.
Speeding also increased at Bankfoot, north of Perth, Faskally, near Pitlochry, Dalwhinnie, and Moy, south of Inverness.
The figures are contained in the A9 Safety Group’s latest quarterly report, which also showed a continued reduction in collisions and injuries.
Neil Greig, the Scotland-based policy and research director of the IAM RoadSmart motoring group, said: “In an otherwise very welcome set of figures, it is worrying to see some drivers are allowing their illegal speeds to creep back up again.
“This may be due to a combination of complacency and a minority of drivers being willing to push their limits to see exactly how much they can get away with.
“IAM RoadSmart will be raising this aspect of the system with the A9 Safety Group to explore possible ways to reinforce the safety message.
“Perhaps reminders are needed on the basic way average speed cameras operate and the fact they are always on.”
Stewart Leggett, chair of A9 Safety Group, said: “Any suggestion that speeding has ‘doubled’ is misleading and does not reflect the real improvements made since their introduction.
“The evidence is there for everyone to see - driver behaviour has improved significantly, with a reduction from one in three drivers speeding to one in ten.
“Instances of excessive speeding has been reduced by over 95 per cent and maintained at one in 250 compared to the pre-camera figure.”
The Scottish Government’s Transport Scotland agency said the figures were “spot speeds” recorded by counters which would show “short term fluctuations”.
It said they were being monitored, but were generally consistent with other UK average speed camera schemes.
Chief Superintendent Andy Edmonston, head of road policing for Police Scotland, said: “We will continue to challenge those who put themselves and others at risk through inappropriate driving behaviour, including speeding.”