A Graphical Method for Rapidly Determining Minimum Vehicle Speeds from Skid Marks

Abstract

based upon mathematical calculations.' Especially in accidents of the auto-pedestrian type, where the vehicle is undamaged, these calculations can be made with reasonable accuracy. The practical circumstances, however, attending the investigation of the average case are rarely conducive to accurate mathematical treatment. Traffic snarls, bad weather, unwilling witnesses, and combative participants are a few reasons why an accident scene is not an ideal setting for engineering computations. While such computations can be deferred, it is usually desirable to know the minimum vehicle speed at the time of the preliminary investigation, in order that the case may receive the proper disposition. The purpose of the present paper is to disclose a simple and rapid graphical method of determining vehicle speeds from skid marks. The logarithmic chart, upon which the method is based, enables any one to make such determinations without resorting to even elementary arithmetic. In order that the method will be clear to those unfamiliar with mathematical procedures, the use and application of the chart will be described after reviewing certain basic considerations. A brief account of the underlying mathematics will then be given.