power is recovered from an escalator or a moving walkway as the step orbits an endless track on rollers . a generator is connected to a roller orbiting the track . a battery backup is provided . the power is used for emergency lighting on the step , and for data transmission . advertising and messages are displayed on a dynamic video screen mounted on the step . the apparatus is mostly contained within the escalator step . information is communicated wirelessly to a remotely located central control station and back to the step , so as to display information in real time and to update advertising while the escalator is in operation . the central control station also monitors performance parameters . the visual display can include led lighting .