The number of people involved in serious accidents on the A9 had dropped by half since the average speed cameras were switched on.
In the six months the system has been active, there has been a 29% drop in the number of accidents between Dunblane and Inverness, compared to the same period in the preceding three years.
There was no collisions on the Dunblane and Perth stretch while the number collisions between the Fair City and Inverness dropped by 5%, with casualties down by 41%.
Police Scotland has confirmed that neither excessive speed nor overtaking was considered to be the primary cause in any of the fatal collisions.
A spokesman for the A9 Safety Group welcomed the figures.
He said: “These most recent figures continue to demonstrate that driver behaviour on the A9 between Dunblane and Inverness has significantly improved since the introduction of average speed cameras.
“This technology continues to be the most effective measure in terms of ensuring compliance with the speed limit, with the A9 system delivering compliance levels in excess of 99.96%.
“Despite rising traffic volumes the recorded number of incidents has continued to drop as well as the impact of these incidents in respect to closures and restrictions on the route. This has resulted in improved journey time reliability between Dunblane and Inverness.“