On elevation

There's been a quiet debate over the choice to put elevators or escalators into a building. Elevators are safe, they take people in wheelchairs, large loads, strollers, etc with the same aplomb. The down side is that they don't work without power.

Escalators, on the other hand, turn into a set of stairs when the power is turned off. Their down side is that they use power constantly, even when they're not in use, until they're turned off completely.

Okay, so, here's an idea for some entrepreneur, for what it's worth:
Create a wide-step escalator that has a button at the entrance point. A wheelchair can enter the stationary step, hit the button and be taken exactly to the exit point (and no further). Add a 20 second delay to insure that someone else doesn't activate the thing while the chair disembarks. Then, people who don't need it, can "take the stairs", and those who do, get escalated at whim.

Someone really creative might make that button a "stop/start request" button. The stairs would have weight or laser sensors to let them know if someone is on, and they keep rolling, only while needed, then automatically shut down when not in use. The button at the entrance would then either stop the escalator while running or start it up while not running. If it's used to start running, it runs through the above, single trip cycle before starting it's auto-roll again.