Initial implementations of PGIS in the early 1970s provided only information about free parking zones around the city
using an inductive loop for tracking available parking spaces. In recent implementations, PGIS provide more specific
information such as directions to empty parking lots and precise location of available parking places for city zones,
parking facilities, and on-street parking. Infrared, ultrasonic, microwave and laser detectors are used for the detection of
available parking places. Some PIGS implementations have also the ability to learn from historical data to forecast
parking demand by time of day. The characteristics of this parking lot management category are reduced parking
queues; relatively high understanding of driver information signs; and visitors to a city are more likely use PGIS than
regular commuters. Drawback of such systems is that travel time and corresponding economic benefits are relatively
small for such a complex system.