Police Minister Liza Harvey has agreed Perth's five fixed speed cameras cannot operate 24 hours a day because authorities could not cope with the number of infringements for speeding.
Her comment came at the launch of WA's new fixed speed camera on Kwinana Freeway north near the South Street exit.
The site, the first with dual remote cameras to photograph the front and back of vehicles, was tested over the past few weeks and began operating yesterday.
During the trial, police detected six hoon drivers doing between 146km/h and 179km/h in the 100km/h zone.
In the past nine years, there have been six fatal crashes and another 25 serious crashes along that stretch of the freeway.
Mrs Harvey rejected criticism that the other four fixed cameras operated only between 9 and 23 per cent of the time, as revealed in _The West Australian _this month.
She said the cameras had a good effect and rotating them gave drivers an incentive to keep to speed limits.
She did, however, admit having the cameras on all the time would create so many infringements to process, it would be a "problem".
WA Police's fleet of Vitronic speed cameras are rotated between the fixed camera sites and mobile locations.
Mrs Harvey called the Opposition "numpties" for suggesting the cameras were revenue raisers because the millions of dollars from infringements went to road safety initiatives.
"It's really a stupid comment to say that speed cameras are a revenue raiser when everyone knows the penalties go into the road trauma trust account to improve road safety," she said.
Shadow police minister Michelle Roberts said the Government was sitting on more than $80 million in the RTTA and used it as a buffer against the high debt it had incurred.
"There's only one numpty and that's the Minister for Road Safety," Mrs Roberts said.
She said the cameras were raking in tens of millions of dollars and this could in some way be justified if it was spent on road safety, but it was not.