The 22 garages already are using automated systems to store and retrieve vehicles, and it's starting to scale up. Ground is breaking soon on a parking structure for a mixed-use development in Oakland, California, and it is claimed to be the newest such fully automated structure in the San Francisco Bay Area—and one of relatively few to allow public access (it will be visitor parking) and to be unmanned. The structure's footprint is just 1600 square feet, the size required by seven surface-parking spots, yet it has 39 parking spaces over seven levels.
You drive the vehicle past a height sensor, then through a garage doorway and onto a platform—which itself is on what look like the tracks you’d find at an automatic carwash. Following instructions on a screen, you exit your vehicle and visit a kiosk to get a ticket that you use to retrieve the vehicle when you return. The system rotates the vehicle, loads it onto an elevator, and then stores it away on the appropriate shelf, potentially several stories up or down in a narrow-footprint building.
SOURCES- CityLift, Car and Driver, Youtube