Which device is commonly used for measuring speed by law enforcement?

Radar and lidar devices are commonly used by law enforcement for measuring the speed of vehicles. Radar technology works by emitting radio waves, which bounce off moving vehicles and return to the device, allowing it to calculate the speed based on the frequency change in the reflected waves. Lidar operates similarly but uses laser beams instead of radio waves. These devices are valued for their accuracy and reliability, making them the standard choice for traffic speed enforcement.

Cameras, while useful for documenting traffic violations, do not intrinsically measure speed unless combined with advanced technology. GPS systems can provide location and speed data, but are less frequently used for direct enforcement purposes due to potential accuracy limitations in capturing high-speed incidents. Smartphone applications may offer speed tracking features but are generally unreliable in a law enforcement context, primarily relying on the capabilities of the phone's built-in GPS. Therefore, radar and lidar devices stand out as the primary tools for traffic speed measurement in law enforcement.