North Carolina RADAR State Practice Exam

The Patrol Speed "Shadowing" Effect occurs when an officer follows a vehicle closely while measuring speed, which can impact the calculations made. In this scenario, the measurement is influenced by the officer's own speed, often leading to a lower-than-actual speed measurement for the target vehicle. When a patrol car is in close proximity to the vehicle being monitored, it may be difficult to accurately assess the differences in speed due to the dynamics of high-speed driving and the relative motion between the two vehicles. The speed of the patrolling vehicle can erroneously subtract from the measured speed of the target vehicle, leading to a misrepresentation of the target's actual speed.

This effect emphasizes the importance of understanding how measurement techniques, external variables, and vehicle proximity can alter speed readings. Being aware of this phenomenon can help officers take more accurate speed measurements and adjust their observations and methods accordingly.