Almost 1000 West Australian motorists have had their licences suspended on-the-spot since new laws came into effect a month ago.

Since the start of August, police have had the power to immediately suspend the licences of people caught driving with a blood-alcohol level over 0.08, or those who refuse a breath test.

The head of the Traffic Enforcement Group, Mike Sparkman, says 936 licences have so far been cancelled on-the-spot.

The majority of the suspensions have been in the Perth metropolitan area with 574 people losing their licence on the spot, while 362 people lost their licence in regional WA.

Senior Sergeant Sparkman says the new laws are proving an effective tool for traffic officers.

"It affects the whole road safety process because it gets the drivers off the road immediately," he said.

"It's causing a far bit of shock to think, 'well, I've probably just blown my job' because they were silly enough to drive with alcohol of that level in their system."

Meanwhile a Main Roads survey has found more West Australian drivers are complying with speed limits.

The 2011 survey showed average speeds remained at, or below, the limit for all speed zones in metropolitan and rural areas.

In the metro area the proportion of vehicles exceeding limits by 10 kilometres an hour or more has dropped from 12.6 per cent in 2000 to 5.8 per cent in 2011.

In rural areas the 2011 speed limit compliance rate of 70.4 per cent increased from a rate of 60.6 in 2000.