Last year, Chan and Jack Levy, a mechanical-engineering professor at City University, unveiled a moving staircase called the Levytator that doesn't double back on itself like a conveyor belt. Instead it loops so that a single installed escalator is actually two moving stairways, up and down. In between the stairways, the Levytator levels out as a moving walkway. There doesn't have to be a landing platform, so it's safer. And, Chan says, repairs are far easier, because only a stair or two needs to be removed at a time. Regular escalators must be entirely dismantled.