Which of the following can affect the accuracy of radar speed measurements?

Radar speed measurements can be influenced by a variety of factors that affect their accuracy. The condition of the radar unit is crucial; if the radar equipment is not functioning properly, it may provide inaccurate readings. Regular maintenance and calibration of the radar unit are necessary to ensure that it operates within its specifications.

Additionally, weather conditions can also impact radar effectiveness. For example, rain, fog, or snow can scatter radar signals and affect how they reflect off vehicles, leading to erroneous speed readings. This interplay between equipment and environmental factors underscores the importance of both the radar unit's condition and prevailing weather when considering the accuracy of speed measurements.

While the number of vehicles on the road and the training level of the operator can influence the context and handling of radar data, they do not directly affect the technical accuracy of the radar speed measurements. Hence, the combination of the radar unit's condition and the weather emerges as the most critical aspects influencing measurement accuracy.