by Stan Erickson
from NMA News Nov/Dec 1995
Cities like to make money in strange ways, and one of those ways is by writing traffic tickets.
A clever ruse used in California is, what might be called, the "Short Yellow Trap." It's very easily done, and very few people catch on to it. Those that do can't do anything about it in court.
The trick works by first setting the yellow lights to four seconds on most of the municipalities traffic lights. Then, on a few well-chosen intersections, the city sets the yellow light to three seconds, and stations a police officer just down the street from the light
The purpose of a yellow light is to allow motorists who are too close to the light to comfortably stop, to continue through it safely. And, most people do so.
In order to make a good decision as to whether to brake or continue, motorists need to have some idea of how long the yellow will last -- it tells them how far back the can be and still make it through
What a surprise when a light turns red before you get into the crossing, too late to do anything but run the red! What a bigger surprise when there's an officer there waiting to ticket you! Most people probably blame their own bad judgment for the ticket; others probably curse their luck for running the light when the police officer just happened to be around. They never stop to think that they've been had.
It's not very easy to tell the difference between a three second and a four second light. It is possible to measure it with a stopwatch though. If you measure a few lights in the neighborhood, you might find a pattern. For example, on a busy thoroughfare with six lights on successive blocks, you might find all but one in the middle lights to be four second yellows. That one is the one that you will be ticketed at.
You could expose the trick in the newspaper by writing a letter. If so, be prepared for the traffic engineer to come up with some technical reason for the three second yellow -- perhaps the cross street is bigger or smaller than the others, or there is a little more or less traffic on it, or any of a host of other excuses.
The last thing you can expect is that they will admit to a ticket trap. The best thing you can hope for is to have the timing changed to eliminate the trap, but don't count on it. If the city catches one person an hour, for twelve hours a day, 365 days a year, and charges $50 for the fine, that's over two hundred thousands dollars a year! The "Short Yellow Trap" is a gold mine for enterprising cities.