The system works by installing wireless sensors in parking spaces that detect the presence of parked vehicles, but do not identify the vehicles themselves. The sensor data is processed to provide drivers with real-time information on how many parking spaces are available on a given street. The information will be provided by variable message signs at the entrances to the car parks and a web interface with a map display. The sensors are fully wireless, internally powered and communicate with the centre via radio waves through repeaters, allowing for a very quick installation on site with minimal modification.