This only works to increase safety if there is evidence that it functions as a deterrent and if there is evidence that accidents on the roads where they are installed are caused at least in part by speeding.
I think the red light cameras do function as a deterrent insofar as I know that I personally won't risk running a yellow if I could end up with a ticket for $85 or whatever it is. As for the speed cameras, I'm not sure what the statistics are.
Do you remember when we had photo radar on the 401 in '93 - '94?
For you non-Canadians, the 401 is the busiest highway/freeway in the North America, and one of the busiest in the world. There are also long portions of it that have a lot of accidents, with one stretch in particular being called "Carnage Alley."
I don't know the stats either, and a cursory check on google didn't reveal any, but I do know that many of the drivers on it are NUTS, driving well over 150 kph/90 mph (the speed limit is 100 kph/60 mph, but no one drives at that speed on it, it's more like 120 kph is the bare minimum, if you drive any lower than that, you'll get run over), tailgating, driving aggressively, whizzing in and out of lanes unsafely. I just know that when photo radar was in use, driving on it
felt much safer than it does now.
It was brought into effect by a provincial NDP government, and removed by the subsequent Conservative government. I remember people at the time bitching that it was a cash grab by the government, which, no doubt it was, but if it resulted in safer driving with more people staying closer to the speed limit, what does it matter?
I just read on a website that it didn't kick in till cars went over 120, but I found nothing official to substantiate that.
For the record, I speed quite a bit too, in the city and on non-400 series highways. Although, like bigjohn said, I only speed when it's safe to do so (good traffic and weather conditions, safe stretches of road, etc), but even I've cut back on speeding in the past few years - can't afford my insurance rates to go up.
In the past few years, they've talked about reinstating photo radar on the 401. I kinda hope they do.