How does it work? When a pedestrian is at the bus shelter and sit on the bank, its weight is dipsplayed on the ad pannel. This is a perfect use of an ambient media with digital interaction.
A successful way to show you that you may walk instead of taking the bus or to subscribe to the gym...
I have found 2 other good ideas of ambient media for Fitness club here and here.
advertiser: Fitness First
agency: N=5 Amsterdam