NCJ Number
216328
Journal
Law Enforcement Technology Volume: 33 Issue: 10 Dated: October 2006 Pages: 70,72-76,78
Date Published
October 2006
Length
7 pages
Annotation
This article describes the speed enforcement functions and specifications of lidar (light detection and ranging).
Abstract
Unlike radar, lidar allows for the targeting of a particular vehicle on a crowded road in order to determine its speed. Lidar uses a time-of-flight method for taking measurements to determine the target vehicle's speed. The calculation of distance traveled over time is computed to determine speed. Radar, on the other hand, shoots out a short, high-intensity burst of high-frequency radio waves in a cone-shaped pattern. It detects a variety of objects within that cone pattern, such as the closest target, the fastest moving target, or the largest target. Under most conditions, skilled users obtain good results with radar, but it is most effective for open stretches of road. For more congested areas, however, locking radar on a specific target is more difficult. Lidar uses laser technology, which allows for superior target tracking in high-volume traffic. A laser can pinpoint one vehicle in a group; radar cannot do this. Lidar readings are also better able to withstand the defense argument in court that has been used with radar, i.e., that the radar reading was actually that for another vehicle on a crowded highway. Although the growing popularity of lidar has eroded the sales of radar, it should not be viewed as a replacement for current radar systems. Rather, lidar should be viewed as another tool for speed enforcement under appropriate conditions. Officers who work traffic enforcement from a car will most likely prefer a standard radar unit over lidar, because lidar is a handheld device. Lidar is most useful for motorcycle officers. Specifications are outlined for lidar devices manufactured by particular companies.