A fixed speed camera on Mitchell Freeway at Innaloo has hit motorists for at least $1.4 million since it was installed in December 2011.
WA's first fixed speed camera, which monitors north-bound traffic near Karrinyup Road, caught a speeder every 11 minutes, police figures show.
A total of 18,432 drivers or one in every 197 monitored were issued with an infringement in the 13 months.
When the camera was installed, 7.4 infringements were issued for every hour of operation.
That number fell to four an hour in June before rising to six in November.
The camera, one of four fixed speed cameras across the metropolitan area, does not always operate and was not in use in July or December last year.
An undisclosed number of Vitronic dual-lens mobile roadside cameras are rotated through sites on the Kwinana Freeway at South Perth and Success, Roe Highway in Willetton and the Mitchell Freeway at Stirling and Innaloo.
The four cameras combined have caught almost 31,000 drivers.
The Roe Highway camera has captured 6124 drivers speeding over 503 hours since it was installed last September.
Its rate of infringements an hour has slowly fallen from 13.1 fines an hour in September to 10.2 an hour in December.
The Kwinana Freeway camera had a remarkable fall in fines from 5.6 an hour in July to just 1.8 an hour in December. Nearly 2500 motorists have been caught at the Mitchell Freeway south camera near Erindale Road in Stirling since it was installed last October.
The four cameras have led to fines of at least $2 million for the Road Trauma Trust Fund based on each fine being the minimum of $75 for low-level speeding at 1-9km/h over the limit.
The State Government's speed enforcement adviser Max Cameron conducted further analysis of the police figures for _The West Australian. _
He found WA Police built up to operating more than 90 per cent of the time in March at the Mitchell Freeway Innaloo site before reducing the hours as the infringement rate stabilised to about 0.5 per cent of monitored vehicles.
He said as an indicator of improved driver behaviour, the figures suggested relatively little improvement.
He was surprised there had not been a bigger change.