Magnetic vehicle sensors are an intrusive technology that sense vehicles by detecting the
distortion of a magnetic field due to a vehicle’s presence. Two general types of magnetic detectors
are passive magnetic detectors and fluxgate magnetometers (Chung & Rosalion 1999b). Passive
magnetic detectors sense the distortion of the earth’s magnetic field when a vehicle passes over
the detector. This type of detector can provide speed and volume data. Fluxgate magnetometers
induce a magnetic field by passing an electrical current in windings around a magnetic material.
Fluxgate magnetometers can detect static magnetic fields and can thus detect stationary vehicl