NCJ Number
188999
Journal
Law and Order Volume: 49 Issue: 2 Dated: February 2001 Pages: 21-24
Date Published
February 2001
Length
4 pages
Annotation
This article reviews the results of using various types of "drag sleds" to determine the "drag factor" (skid number or coefficient of friction) in traffic accident reconstruction.
Abstract
There are a number of ways to conduct skid tests in reconstructing the distance a vehicle skidded prior to impact or the distance it traveled afterwards. One of the ways is with a drag sled, which comes in all shapes, sizes, weights, and designs. The author's own version of a drag sled is an old 30-pound wooden ammo box with bricks inside and with rubber tire material on the bottom. Some years ago, an entrepreneur produced a professional-looking device that contained intricate instrumentation that gave the user a digital display of the drag factor as the contraption was pushed along a surface. The sled was attached to a two-wheeled hand push-cart or dolly. When the dolly was pushed the sled was dragged behind it. At the World Reconstruction Exposition 2000, various drag sleds were tested. There were 15 devices, enough to make the testing worthwhile. A "generic" drag sled with a digital scale was also tested. Various persons were recruited to use the drag sleds so as to observe differences among various users of the same sled. Results differed among participants due to the angle at which they pulled the sled. An improved test is being designed. This article also discusses how the surface on which the accident occurred may affect the drag factor.