I have heard about garages (there's one in or around Washington D.C.) that have displays which direct drivers to the open spaces. Does anyone have information about such a garage?
I was in Arizona 2 weeks ago and they had a news story about this. The system was being tried in Pheonix I believe. You might try calling the Pheonix airport to get some information.
The one near D.C. is located in the terminal parking garage at BWI (Baltimore Washington International). At this point it is a limited installation. As I understand it it uses a sensor, type unknown, to determine the presence of a car in each space. If there are open spaces iluminated arrows at the end of each row point down the row. If all the spaces are filled the display changes to either an X, or a "no free spaces" message, I ca't remember which.