POLICE admit they would never have known a speed camera was wrongly churning out fines if a lone motorist had not challenged an EastLink ticket.
One of the busiest fixed cameras in Victoria was meant to be turned off after snapping a test vehicle travelling 1km/h faster than it was.
But the wrong camera was turned off and hundreds of motorists were fined after being pinged by the supposedly deactivated camera.
The camera on northbound Lane 2 at EastLink's notorious Wellington Rd Bridge in Rowville was responsible for 10,490 motorists paying fines of $1.76 million in the past financial year.
Victoria Police yesterday said although it was confident every motorist caught was actually speeding, all 717 fines issued during the month the camera was supposed to have been turned off would be withdrawn and demerit points removed.
Speed camera watchdog Gordon Lewis yesterday vowed to fully investigate the foul-up and told the Herald Sun he would "pursue my inquiries with some vigour" to try to ensure the problem never happened again.
Police Assistant Commissioner Andrew Crisp blamed human error and "a systems breakdown" for the embarrassing bungle.
The problem was discovered late last week when police were preparing a brief of evidence against a motorist who was contesting an EastLink fine in court.
Every fixed speed camera is tested for accuracy every three months and one of the tests involves a vehicle with a calibrated speedometer.
Mr Crisp said on one of the 10 times the offending camera was tested it recorded the test vehicle travelling 1km/h faster than it actually was.
The private company contracted to operate speed cameras, Serco, deactivated the wrong one.
Mr Crisp said further tests showed the camera was operating correctly and the fines were being withdrawn only because they would not have been issued had the right camera been turned off.
One of the motorists, Margot Haynes of Nunawading, said she would demand her money back.