Abstract: A vehicle detection unit (VDU) is embedded beneath each of a plurality of parking spaces. Each VDU has a sensor which detects magnetic field fluctuations caused by the arrival and departure of a vehicle in the parking space. The VDU runs a vehicle detection algorithm to distinguish magnetic fluctuations caused by vehicles from “exceptional” magnetic fluctuations from other sources. The VDU also stores parameters which define notifiable vehicle space occupancy events. A processor of the VDU processes the sensor signal to determine occupancy status of the vehicle space, and compare the occupancy status of the vehicle space with the parameters in order to determine whether a notifiable event has occurred, such as a vehicle going into violation of parking restrictions. As necessary, the VDU initiates radio communications with a supervisory device, either a transient portable device such as a Parking Officer's PDA or a fixed radio node mounted within range.