Magnetic gradient vehicle detector

The design, analysis, and selected measurements of a new type of vehicle detector called a magnetic gradient vehicle detector (MGVD) that is under development by the Federal Highway Administration are described. The detector consists of a transducer buried in a transverse slot in the pavement surface. "Lead in" cables connect the transducer to roadside detector electronics. When a vehicle approaches the transducer, eddy currents are induced in the vehicle's undercarriage, front, and possibly side surfaces, and the resulting magnetic field is sensed by the transducer. The operating frequency of the detector is nominally 100 kHz.