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.