Speed cameras were installed on eight routes across Lancashire between March 2017 and August 2018.
Police said they had proven to reduce both collisions and casualties, with speeding offences reduced by more than half since they were installed.
Following the “success of the installations,” projects were put in place to install five further average speed camera routes in Lancashire.
Supt Damian Darcy, of Lancashire Police’s Tactical Operations, said: “Slower speeds mean safer roads for all road users, residents and communities.
“We thank those drivers who obey the limits. We are pleased to see that the number of both collisions and offences detected on these roads has reduced so significantly.
“Those who continue to choose to speed on Lancashire’s roads will not be tolerated and offenders will continue to be dealt with appropriately."