Speed cameras across Oxfordshire have been switched back on eight months after they were turned off.
Funding was withdrawn for 72 cameras and 89 mobile sites last August as part of budget cuts.
Police said since then deaths and serious injuries on roads had increased across the county but accidents away from fixed cameras fell slightly.
The cameras, paid for by speed awareness courses and backroom savings, were switched back on at 0900 BST.
Data released by Thames Valley Police revealed in the six months after they were switched off there were 70 slight injuries, 13 serious injuries and no fatalities from a total of 62 accidents at fixed camera sites.
In the same period the year before [August 2009 to January 2010] there were 55 slight injuries, 13 serious injuries and no fatalities from a total of 60 accidents.
Away from camera sites there were 867 collisions with 982 slight injuries, 179 serious injuries and 18 deaths during the period the cameras were turned off.
In the same period the year before there were 885 collisions with 999 slight injuries, 160 serious injuries and 12 deaths.
Supt Rob Povey said speed enforcement worked as a deterrent to motorists.
"We think this is important because we know that speed kills and speed is dangerous," he said.
"We have shown in Oxfordshire that speed has increased through monitoring limits and we have noticed an increase in fatalities and the number of people seriously injured in 2010."
The cameras were switched off after funding was withdrawn by Oxfordshire County Council following government cuts to the authority's road safety grant.
It had to save £600,000 from its road safety budget - money which would have been given to the Thames Valley Road Safety Partnership.
Councillor Rodney Rose said: "The county council did not delight in withdrawing funding for speed cameras last year, but took this decision to protect other service areas following a huge reduction in road safety grant from the government.
"Other councils across the country took the same view."
A spokesman for the Association of British Drivers said the council had "gone round the bend".
He added: "A whole lot of areas are turning them off and as far as we are concerned it is good news all round so people can get on with driving without worrying about these cameras.
"Drivers need to concentrate on more than just speed when it comes to driving safely."
But Ellen Booth, of the road safety charity Brake, hailed the return of the cameras as "fantastic news".
"It was madness and immoral that they were switched off," she said.
"There's so much evidence to show just how important they are for preventing deaths and injuries on the roads.
"Speed cameras are one of the most cost-effective ways of reducing casualties and they pay for themselves."