Inductive loops are considered the most reliable traffic classification detection method available.
An inductive loop consists of wire "coiled" to form a loop that usually is a square, circle or rectangle shape that is installed into or under the surface of the roadway.
Inductive loops work like a metal detector as they measure the change in the field when objects pass over them. Once a vehicle drives over a loop sensor the loop field changes which allows the detection device to detect the presence of an object (mainly a vehicle). Inductive loops are referred to as presence detectors and in traffic detection are often used in combination with axle sensors to collect classification data such as speed and length data.
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