Radar speed meters which operate on the radar principle are normally used for making speed checks. These devices operate from the power of an automobile battery and give direct readings of vehicle speeds in miles per hour which are accurate to within 2 miles per hour.

New technologies may be used in determining vehicular speeds for use in calculating 85th percentile speed if the measured speeds are accurate to within 2 miles per hour and the gap between vehicles is 3 seconds or greater. Examples of new technologies are counter-classifiers with the capability of classifying vehicles, determining vehicular speeds, and differentiating the gap between vehicles. These devices may include video imaging, tube counters, magnetic counters, inductive counters, etc.