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Measuring at the Scene of Traffic Collisions (From Traffic Collision Investigation, Ninth Edition, P 183-255, 2001, Kenneth S. Baker, -- See NCJ-197110)

NCJ Number
James P. Sneddon
Date Published
73 pages
This chapter offers methods for taking measurements to produce excellent results with minimal equipment requirements without interfering with traffic or exposing the investigator to unnecessary hazards.
The extent to which an accident can be reconstructed is dependent on the evidence collected at the scene. This chapter discusses the importance of measurements that are taken. Photos and diagrams accompany each description of methods of measurement. Points to be located are described, including the coordinate method of locating points, triangulation method of locating points, angle and distance method of locating points, and other measuring methods employed by engineers and surveyors. In terms of measuring the road, locating edges and lanes, measuring offset pavement edges, angled intersections, curves, grades, and vertical measurements are discussed. The creation of field sketches, including only factual data, by using a roadway skeleton, identification, description of collision result, and labeling are covered. A sample table of measurements is shown. The different types of necessary equipment and their use are discussed, such as global positioning systems, tapes, data collectors, plumb bobs, levels, marking supplies, and laser distance meters. Drawing after-collision situation maps including street and highway plans, and curve data are covered and also illustrated. Computer-aided drafting instruments and methods are covered, including map layout and diagram drawing, accompanied by illustrations of recommended symbols to be used. A list of reference sources is included at the end of the chapter.