A study into casualty statistics at speed camera sites suggests that they may not need to be switched on to have an effect.
A report into casualty statistics at speed camera sites in Northamptonshire found “no significant change in collision rates at the fixed camera sites post-switch-off compared to the collision trends seen elsewhere in the county”.
Northamptonshire Speed Cameras: Post Switch-Off Collision Analysis found that this was “significant as many people would have expected a rise in collisions”.
The report looks at the four-year period prior to the cameras being switched off in March 2011 and the four years after to March 2015.
In the period after the cameras were switched off, the findings highlight a 45% reduction in KSI at camera sites compared with a 27% reduction across the rest of the county’s road network. In the same period, casualties of all types at camera sites were down 21% while across Northamptonshire’s other roads there was a 29% fall.
The report concluded “the changes between the two periods for Northamptonshire’s roads and the speed camera sites are not statistically significant”.
Report author Richard Owen from Road Safety Analysis said: “What these results show is the collisions have actually reduced in the post-switch-off period and that the variation in reductions against the Northamptonshire average of all other roads is not significant. It could therefore be said that the cameras have continued to ‘work’ despite their inactivity.”
He added that the main reason for this could be that drivers have not changed their behaviour at camera sites over the last four years.
“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,” he added.
However, Owen warned that 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. Previous, unpublished research by the author has shown that bagged cameras have an immediate impact on vehicles speeds, which return to normal once the bags are removed.
Owen concluded: “The most significant outcome from this analysis is that fixed speed cameras do not need to be loaded regularly to achieve casualty reduction. This could significantly change how cameras are operated nationally with the potential to reduce costs associated with the loading and processing of offences. The savings could be used to support more widespread deployment of enforcement cameras in more locations with lower loading ratios.”