Abstract: An apparatus for detecting inductance, which is generally disposed outside of the roadway surface. The apparatus includes at least one large aperture wire-loop deployed beside the roadway, on either or both sides, to detect vehicular traffic passing nearby. Alternatively, the apparatus includes at least one large aperture wire-loop deployed such that vehicular traffic passes through the opening defined by the wire-loop(s).

Abstract: An apparatus for measuring the inductance of a wire-loop with noise-cancellation, auto-calibration and wireless communication features, or detector circuit. The apparatus measures the effective change in inductance induced in a wire-loop as a vehicle passes over the wire-loop to produce an inductive signature corresponding to a vehicle.

Abstract: A system and method for measuring a plurality of successive induction measurements, collectively known as the “inductive signature” of a vehicle, and classifying the vehicle described by the measured inductive signature. The system includes a blade-type wire-loop configuration, or blade sensor and a corresponding measurement circuit employing a discrete measurement technique, as opposed to the frequency counting technique of the prior art. The system and method produce repeatable inductive signatures at a high resolution that allows for accurate identification and classification of a vehicle.