Northamptonshire County Council withdrew its £1 million a year funding to the county’s Casualty Reduction Partnership in 2011, which led to more than 40 the yellow speed cameras in the county being switched off.
Some cameras remain on major routes through the county such as the M1.
The majority of the yellow camera shells have remained in place for the past four years.
When they were first switched off road safety campaigners claimed the move could endanger lives.
But a study by Banbury-based Road Safety Analysis Limited claims collisions where a person was killed or seriously injured have actually fallen by 27 percent in the county in the four years since they were turned off.
The report, entitled, Northamptonshire Speed Cameras: Post Switch-Off Collision Analysis, states: “Given the significant reduction in collisions immediately following the installation of the cameras up to 15 years ago, many would expect collisions to rise again once they were switched off.
“What these results show is the collisions have actually reduced in the post-switch-off period.”
The study worked by tallying the number of accidents on roads with speed cameras in the four years before they were switched off and the four years afterwards.
On roads with speed cameras serious accidents have reduced by down 45 per cent.
The report shows there were 29 serious crashes on speed camera roads between 2007 and 2011 and only 16 afterwards.
Accidents have reduced greatly in areas where there were average speed cameras, which measure drivers’ speed over a fixed distance. There were 30 accidents in the four years up to 2011, but only 19 in the four years after.
However the report’s author Richard Owen states the results do not necessarily mean the yellow speed cameras are ineffective, because just the yellow camera shells can have an effect on driving.
He said: “Anecdotal evidence from residents suggests that the vast majority of drivers still stick to the limit when passing camera sites, although there may be a small majority who choose to flout the law in the knowledge a ticket will not arrive in the post.
“Motorists may still be under the impression that the cameras are working as the housings are regularly maintained and not covered in bags stating they are out of use.”
Northamptonshire saw a rapid expansion in speed cameras during the early 2000s. A total 46 cameras were installed at 41 separate sites between August 2000 and October 2004.
This was made possible due to a pilot scheme setup by the Government that allowed local partnerships; comprising of police forces, local authorities and the courts; the ability to recover enforcement costs directly from fine income.
This cost recovery system ended in 2007 and with increased pressure on local authorities for funding the Northamptonshire speed cameras were switched off in April 2011.