NCJ Number
73232
Journal
Schriftenreihe der Polizei-Fuehrungsakademie Issue: 3 Dated: (1980) Pages: 207-221
Date Published
1980
Length
15 pages
Annotation
A new evidence collection technique for measuring and recording the distance between cars on the open road is described in this West German paper.
Abstract
The traditional technique involves the installation, usually on a bridge, of a camera and a long measuring frame which has been marked with lines separated from each other by known distances. The camera takes two pictures: one at the beginning of the measurement stretch and one at the end. A stopwatch is used to measure the time traveled from end to the other. As a result, the speed of the cars involved, the distance between them, and the identities of the cars and their drivers are recorded. The new technique eliminates the need for the measuring frame and allows the same results to be obtained on any street. The distance measuring device is built into the camera through the use of a T-shaped objective tube. From a tube (the base of the T) which has been attached to the side of the lens tube (the top of the T) the measuring frame is projected over the image each time a photograph is taken. This is accomplished through the use of a light source, a plexiglass slide containing the image of an actual measuring frame, two lenses, and a prism for directing the slide's image up the lens tube to the camera. The light source is incorporated into the plexiglass slide in order to obtain a bright image of the measurement lines on the resulting photographs. The length of the tube containing the measurement slide is adjustable so that the camera may be used in various locations along a street. Before use, tube length adjustments are made for obtaining the proper calibration. Objects along the road which are of known size can be utilized for this procedure. Technical information, diagrams, a photograph, and a bibliography are included. -- in German.