Speeding is always an essential part of evidence before the
court in a DUI case. Police departments currently use four
primary speed measurement devices: 1) speedometer clocks, 2)
radar, 3) average speed computers and 4) LIDAR (Light Detection
and Ranging). Two additional types used to a lesser extent are
1) aircraft and 2) photo radar. Each method has its own
advantages and disadvantages. a. Speedometer Clocks Speedometer
clocks have gradually been replaced by more technologically
advanced methods, but they are still the least expensive method
of clocking speeders and can be extremely effective. The patrol
car speedometer is used to pace vehicles. The most important
component of this method is an accurate speedometer that is
factory certified. A speedometer can be calibrated several ways:
via the fifth wheel attached to the rear of the vehicle; using a
stopwatch that has been certified to clock the patrol car over a
measured course; or using a dynamometer, which allows the patrol
vehicle wheels to rotate in