Here are two images and a bit of a lesson in consequences:
The vehicle in the top picture is out generating revenue by taking pictures of motorists speeding, the guy in the bottom picture is warning drivers that the guy in the first picture wants to take a ticket of them speeding. Which is the actual deterrent?
A very wise man named Aubrey Daniels wrote a book 30 years ago called Performance Management about how to positively and negatively reinforce behaviour so that behaviour would either be repeated or diminished.
His correct contention was the feedback and consequences, either positive or negative were the determining factor to whether or not a particular action would change. Key to this premise were two factors:
2) Immediacy, i.e. a correlation between the action and the consequence.
Daniels, contended, correctly, that the key to either getting more of what you want, or less of what you don't want was to deliver a consequence that was certain and immediate.
Imagine going bowling in the dark and having your score mailed to you three weeks later, not only would this limit your enjoyment, but you would also lack any sort of feedback to determine if you were getting better, worse or if you made that railroad split ten pin bowlers are so proud of.
So too it is with photo radar in Edmonton. The guy in the bottom picture is FAR more effective at getting people to slow down than the radar vehicle because:
1) He has created an immediate and a certain consequence to not slowing down.
2) Photo radar has no close proximity in time and space, you get a picture in the mail three weeks after you drove 56 in a 50 zone past an unmarked photo radar truck you never saw.
From this one can only assume that the delayed consequence for speeding, getting a photo radar ticket in the mail is not a reliable deterrent or an effective means of creating consequences for the behavior we want; people driving at the speed limit.
The issue is further muddied by the unclear consequence the purveyors of photo radar desire: Is the goal of photo radar to get people to drive at the legal speed limit or to punish them for not driving at the legal speed limit? This is not the same thing.
In certain areas you will see large signs that display the speed of your vehicle, indeed the Alberta Motor Association has created an traffic control group for tow truck drivers that include a portable sign to show how fast you are going, people see the sign and they slow down, or speed up to the correct speed. Nice and simple.
Photo radar on the other hand has no such attributes. You may not be aware you were speeding and get getting punished for something you do not even remember doing. If you get stopped by a real cop for speeding, it happens when you are speeding and you get a ticket or a stern warning. Immediate feedback and a certain consequence. All of this is wrong and missing with photo radar.
Governments have deliberately missed the boat on consequences, and one can really only attribute this to their addiction to the revenue behaviour creates. Photo radar is cheaper to do than actual traffic enforcement and brings in the dollars. I think the cheapest way would be for the guy with the sign to stand on any busy road, people would slow down.
So I am led to believe the real purpose of photo radar is revenue. Some would argue that if you don't speed you won't get a photo radar ticket, true, but it is not the fear of photo radar that keeps me from getting a ticket, it is driving with common sense to the conditions that does.
Photo radar is, in and of itself no deterrent at all.
Taken in another direction. a big source of government revenue is gambling. Oh we wax poetic about the damage done by VLT machines, if we really wanted people not to gamble, I could fix the problem in about five minutes: Every time you put a dollar into a VLT and lose the machine would shout "LOSER!!" people would stop using the machines in short order. But since VLT gambling revenue is important to government, they'd rather spend money on gambling addiction treatment to show they are doing something about the problem than make the process of gambling itself less rewarding.
In order for consequences to be effective they need to be immediate and certain. Any other form of consequence and I respectfully suggest one should:
a) Find out who make the money.
b) Well, really the first one pretty well covers it.