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Topic: Mapping & Measuring
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| Monday, December 9, 2002 |
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ACCURACY, ERRORS AND TOLERANCES IN TRAFFIC ACCIDENT SCENE MEASUREMENTS -- The investigator should be aware of the inherent errors that are or might be found in measurements and calculations made in traffic crash investigations, and methods that can be employed to recognize and compensate for them so that the most accurate results will be achieved and reported upon. In most cases, any such error will be associated with the device or with the procedure used to make the measurement. For these purposes, error is defined as the absolute difference between the true value and the read value and may be classified as systematic or random. Systematic errors are the result of bias in the measuring device or procedure. Random measurement errors are the result of a number of random influences which usually follow some statistical distribution.
Table 1: ±% ERROR BY METHODS AND DEVICES IN TESTS CONDUCTED OVER A DISTANCE OF 100 FT (30 M)]. Pacing Method = 10.2; Heel-to-toe Method = 5.1; Pocket Tape = 0.1; Woven Metal Tape (New)= 0.2; Woven Metal Tape (Old)= 0.5; Cloth Tape (New) = 0.3; Cloth Tape (Old)=1.0; Measuring Wheel = 0.5
Source: Patterson, G. (1991). Significant Figures and Errors for Collision Reconstruction, cited by Navin, Francis, P.D., in his paper: The Accuracy and Precision of Speed Estimates from Accident Reconstruction Data, prepared for IPTM's Special Problems Seminar, May, 2000. For additional information on field measurements and plan drawing, see: Rivers, R.W.: TRAFFIC ACCIDENT INVESTIGATORS' AND RECONSTRUCTIONISTS' FIELD MEASUREMENTS AND SCALE DIAGRAMS MANUAL (2nd ed.)To be published by Charles C Thomas Ltd., early 2003.
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Posted by: R.W. (Bob) Rivers on 11/23/2002 @ 12:04 AM
Amended: 12/9/2002
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| Friday, October 11, 2002 |
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TRAFFIC TEMPLATES FOR PREPARING SKETCHES AND SCALE DIAGRAMS AND PLAN DRAWINGS
All templates are available from IPTM - miniBlitz Field Sketch Template. [A pocket-size template for quick drawings.]
- blueBlitz Traffic Template. [Contains the symbols and scales most frequently used in AI and AR.]
- rigBlitz [Commercial Vehicle Template.]
- nautiBlitz Marine Template. [Marine accident investigation template.]
- Crime Scene Template. [A template for all forms of crime scenes.]
- AeroBlitz Aircrash Investigation Templates. [A total of 10. Each being a different type and model of aircraft having silhouettes that satisfy dozens of different types of aircraft].
- Grade Gauge. [Roadway Slope Measurement Device.]
- 360-degree Counter Clockwise Protractor.
NOTE: Most templates are prepared in both US and Metric measurement systems.
For further information and/or to place an order, click on: http://www.iptm.org
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Posted by: R.W. (Bob) Rivers on 10/11/2002 @ 03:41 PM
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