What can Doppler microwave detectors measure?

Doppler microwave detectors utilize the Doppler effect to measure the movement of vehicles as they approach or pass by the sensor. This technology allows for the detection of the speed of vehicles, as the change in frequency of the reflected microwaves varies with the velocity of the moving vehicle.

Additionally, these detectors can provide data on vehicle volume by counting the number of vehicles detected within a given time frame. They also have the capability to classify vehicles based on their speed and size. This information is critical for traffic management as it can help in optimizing traffic signals, analyzing traffic patterns, and improving overall roadway efficiency.

While the other options address important aspects of traffic management, they do not accurately depict the specific capabilities of Doppler microwave detectors. For instance, occupancy refers to whether a particular space (like a parking spot or lane) is occupied, which is a different measurement than speed or volume. Traffic light timing is managed by traffic control systems rather than detected by these sensors. Road surface temperatures would typically require different technology altogether, such as infrared sensors or other forms of thermal detection. Thus, the correct choice emphasizes the comprehensive capabilities of Doppler microwave detectors in measuring traffic flow characteristics.