In "Whale Watching" in the March/April issue of Truck Trend, G.R. Whale questions who is responsible for any tickets if the offender's speed is based upon a radar traffic speed sign. As a recently retired police officer, I have some background info here. First, the traffic-calming signs are intended to bring to attention the speed of a person's vehicle; the driver may otherwise be distracted by things such as cell-phone use, being late, or just daydreaming and not realizing the speed limit. Hence the flashing numbers-to get your attention. As far as speeding tickets, it's been my experience that the speed cushion given by an officer varies from 8 to 15 mph (and even 20 mph on the Interstate) before a ticket is issued, depending on the location, speed zone, and police department. When an officer issues a speeding ticket it's "based on visual estimation and substantiated by a calibrated radar device." The cop was visually estimating the speed and backing it up with a radar gun. The margin of error is + or - 5 mph, and is one reason for the speed cushion. I'm not aware of any speed signs working correctly that have this margin of error. You're not going to get stopped because of the 1-2 mph deviation of the speed sign. The latest trend is video enforcement, with the offender getting a ticket in the mail. I don't know what the speed is based on or how it holds up in court. I would think there would still have to be a margin of error designed into the system.
Kevin McDonough
Via the Internet
Dear Reader --
Thanks for the insight. It's also nice to know there is some wiggle room when it comes to speed limits--depending on the officer, of course.
-Truck Trend
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