NCJ Number
180734
Journal
Law and Order Volume: 47 Issue: 11 Dated: November 1999 Pages: 45-47
Date Published
November 1999
Length
3 pages
Annotation
This article examines issues in the long-standing debate over whether or not law enforcement agencies should use laser mapping systems or total station technology in their traffic crash and criminal investigations.
Abstract
Total stations are precision instruments that are capable of recording data over long distances with a high degree of accuracy. Some complex crash scenes require total station technology to create an accurate depiction of the various points of interest (i.e., roadway profiles, sight distances, roadway evidence, etc.). Current laser mapping systems are also capable of accurate measurements, however. Critics of the dual-purpose lasers (units capable of measuring both speed and distance) argue that the units measure slope distance only and do not account for differences in elevation. Although this is true for certain dual-purpose units, there are laser models available that are capable of measuring elevation. One such model is the Impulse, which is manufactured by Laser Technology. Another criticism of laser mapping systems is that they cannot accurately produce crush profiles of vehicles. Critics maintain that it is impossible to use lasers for this purpose because the user cannot physically position the unit at the various points of interest within the damaged area. It is possible, however, to use the Quickmap 3D software with the Impulse to accomplish this task. Using the range triangulation method described in this article, the user can select two control points near the damaged vehicle. These control points are usually marked with paint or surveyor stakes. When mapping crush profiles in this manner, an assistant is required. The assistant holds a reflective target over the particular feature. The user then completes the measurements in the manner described in this article. Instead of measuring from the feature to the control point, the Impulse measures the distance to the target from each control point. The Impulse laser, along with the Quickmap 3D software package, gives investigators the flexibility needed in law enforcement. It allows investigators to quickly obtain the necessary data at traffic crashes, crime scenes, or other police tasks.