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Why does every escalator in the world have those green lights in the works under the steps at the bottom and the top? And why always the same shade of green?

-- Steve, the net

See, if the finger-in-the-chile lady had just considered her personal injury options with escalators, she might have done a little better in court. But maybe having received a windfall like a severed finger was just too much to resist. Anyway, she was barking up the wrong tort. Escalators are where it's at. And because of that, escalators are designed with as many safety features as their lawyers can think up. The green fluorescent lights at the top and bottom are called step demarcation lamps. As you step onto the flat platform formed by three or four steps at the top and bottom of the machine, the green light below the platform shows where each step ends. That way you can move your foot onto a full step tread and not be caught between two as they rise up to form stairs. The color is a mid-spectrum hue judged by the American Society of Mechanical Engineers as the most visible under those conditions. And since the ASME sets the safety guidelines, everyone must follow

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