NCJ Number
59487
Journal
International Criminal Police Review Issue: 325 Dated: (FEBRUARY 1979) Pages: 48-53
Date Published
1979
Length
6 pages
Annotation
THIS STUDY OF THE RELIABILITY OF SPEED ESTIMATES MADE FROM SKID MARK LENGTHS WAS PREPARED BY LONDON'S FORENSIC SCIENCE LABORATORY WHICH PROVIDES AN ADVISORY SERVICE TO THE POLICE FORCES IN THE SOUTHEAST OF ENGLAND.
Abstract
REFUTING CONTENTIONS PRESENTED IN AN EARLIER ARTICLE THAT SKIDMARKS ARE UNRELIABLE INDICATORS OF VEHICLE SPEED DUE TO THE COMPLEXITIES OF THE FRICTION OF SLIDING RUBBER, THIS PAPER STATES THAT SPECIFIC EXPERIMENTS ON SKIDDING VEHICLES HAVE SHOWN OTHERWISE. A SERIES OF CAR SKID TESTS SHOW THAT IT IS POSSIBLE TO DERIVE SPEED FIGURES FROM SKIDMARKS WITH AN ACCURACY OF PLUS OR MINUS 5 PERCENT, PROVIDED CERTAIN CONDITIONS ARE MET. THESE CONDITIONS ARE THAT THE ROAD BE DRY, THAT THE SKIDDING VEHICLE HAVE ALL ITS WHEELS LOCKED, AND THAT THE COEFFICIENT OF FRICTION IS ACTUALLY MEASURED SHORTLY AFTER THE ACCIDENT. VARIOUS ASPHALT AND CONCRETE SURFACES WERE USED FOR THE TESTS ALONG WITH A SELECTION OF TIRES AND TWO CAR TYPES. REFERENCES ARE CITED, AND STUDY DATA ARE PRESENTED. (MJW)