Large scale sensor network connected to public displays

The airport Köln-Bonn (CGN) has all the parking spaces monitored with a simple sensor (detects if there is a car or not) and provides displays at the entrance showing the number of open spaces and has active signage in the parking garage leading to the free spaces - additionally it is visualized above each space – probably more a maintenance functions to see if the sensor works.

(looking at the pictures I have probably parked on women-only parking spots...)