Tuesday, June 05, 2007

In many of the articles and user manuals written about handheld radar guns, you will almost always see a section on the cosine effect. Basically stated, this is how the accuracy of the radar gun is affected by the angle in which you are standing from the path of the target. Almost all of these article are written to show how close you need to stand to the directional path of traffic or the baseball being clocked.

I was recently asked if the cosine effect could be eliminated by targeting traffic with a handheld police radar gun standing directly over the highway on an overpass. This was a great question, because according to the way these articles and manuals are written, this would eliminate the cosine effect. Unfortunately, the writers did not take this scenario into consideration. The cosine effect is three dimensional. The same principles that apply to standing along the side of the road also apply to standing above it on an overpass. Based on the height of most overpasses that accommodate a full size tractor-trailer, this would actually be a worse place to stand than the side of the road.

Ryan