The number of people killed or seriously injured on a stretch of the A77 in Ayrshire has halved since the introduction of average speed cameras.
The cameras check the average speed of cars on the road
The number of casualties dropped from an average of about 22 a year before cameras were introduced in August 2005, to about 11 a year afterwards.
The figures have been released by the A77 Safety Group.
It said the number of fatal or serious accidents had also gone down by more than a third.
Hugh McCafferty, from Transport Scotland and chair of the A77 Safety Group, said: "We know speed often plays a major part in both the cause of accidents and the resulting severity, this would appear to be borne out by the interim figures.
"Looking beyond the figures, the initiatives on the A77 have reduced the personal tragedy experienced by individuals, families, friends and colleagues.
"This is what the A77 Safety Group is trying to achieve. The most important element in road safety is always the road users."
The number of deaths or serious casualties dropped from an average of 21.7 before the cameras came in, to 11 after two years in operation.
The effectiveness of the system will be fully assessed after it has run the third year of its trial on the 32-mile stretch, from Bogend Toll north of Ayr to Ardwell Bay south of Girvan.