What can radar speed detection devices sometimes not differentiate between?

Radar speed detection devices can have difficulty distinguishing between multiple close-proximity vehicles due to the way radar waves interact with objects. When two or more vehicles are traveling close to each other, the radar signal may bounce off both vehicles simultaneously, causing the device to record an average speed rather than distinguishing each vehicle's individual speed. This phenomenon is known as "radar masking," where the presence of nearby vehicles can confuse the radar's ability to accurately measure speed.

In scenarios where vehicles are closely packed, it is challenging for the radar system to isolate the signal reflected from one vehicle versus another. Consequently, if two vehicles are side by side or within a small distance of each other, the radar may not be able to provide precise readings for each, resulting in potential inaccuracies in speed detection.

On the other hand, radar devices are generally able to differentiate vehicles based on weights and speeds, or can distinguish colors, as these factors are less likely to overlap or interfere with the radar signal. Therefore, the challenge lies specifically in the detection of multiple close-proximity vehicles rather than the other factors described in the other options.