the primary assumption is that speeding is dangerous, therefore we have speed limits. we enforce those speed limits because we believe driving slower is safer.
now let's think about how a speed trap works. a cop hides on the side of the road, over the crest of a hill, or a around a bend or behind a sign. traffic, generally all moving along at the same pace, well above the speed limit, comes across this speed trap and the guy in front slams on his brakes even if he's only going 5mph over. if we're lucky, everyone behind him just slams on their brakes too and avoids a pile-up, resulting (at least around DC) in a 4 mile traffic jam where it's not possible for even the most dedicated of speeders to break the speed limit. and then as soon as everyone is past the speed trap, they all speed back up to their 15mph-over-the-limit speed.
on the other hand, consider what happens when a driver comes across a sign warning of speed traps ahead. they read the sign, they take their foot off the accelerator and gradually slow to the posted speed limit. drivers will then either continue at that speed until they pass an actual speed trap, and assume that no further danger exist and speed back up, or until they have traveled a sufficient distance that they feel the warning is no longer relevant and there is no risk of getting ticketed, and speed back up.
now if we go back to our original premise that speed limits enforcement is for safety, not adding to the coffers, out of these three options, which one sounds the safest to you?
- speed trap
- warning sign followed by an actual speed trap
- warning sign with no speed trap
i'll tell you the answer since i'm a know-it-all.
it's the last one. drivers will slow down with the least likelihood of an accident and continue at that slower speed for the longest amount of time. other benefits? the cop can go do something useful. now can someone please explain why cops get all huffy-puffy about speed trap warnings?
don't get me started on speed cameras / photo radar.
