a parking guidance and management system . the system provides graphical information regarding the relative availability of parking spaces within a parking garage or other large facility . the system relies on a pair of sensors in each space which combine to provide highly reliable information regarding whether spaces in the facility are occupied or not . the information is gathered by a series of aisle controllers , which communicate with a central computer . the information is displayed at strategically located displays along the way to available spaces . the displays contain advertising messages adjacent to the information about space availability . the information obtained from the sensors at each parking space may be used to provide information to the manager of the facility regarding space utilization . information regarding the occupancy status of each space may also be used as a check on receipts of parking fees and to identify abandoned vehicles .