According to CityLab, Japan’s trains rely heavily on so-called “nudge theory,” or small signals that almost unconsciously influence riders’ behavior, keeping foot traffic moving smoothly through crowded stations. These go well beyond the basics of clear boarding indicators, well-designed maps, and fully audible announcements—which too many U.S. transit systems already have trouble executing.

For example, Japanese train systems use calming melodies to signal departures instead of harsh buzzers, which studies have shown prevent injuries by keeping passengers from rushing. Slightly more Machiavellian is the use of ultrasonic sound, inaudible to older passengers, to disperse crowds of potentially disruptive teenagers.

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The use of subtle nudges also extends to train operators, who are expected to gesture with their hands and state any intended action out loud. That increases mental engagement and decreases operating errors.

Much more serious is the use of calming blue lights on certain parts of platforms, which have been shown to reduce suicide attempts by people jumping in front of trains. Suicide in general is a major social problem in Japan, and suicides by train also cause frequent, serious disruptions to the otherwise smoothly operating system.

Preventing small or large disruptions is crucial to the efficient functioning of mass transit—just ask any New Yorker who has ever boiled with rage when new passengers cram into a subway car without letting exiting riders off first. But for American supporters of mass transit, such refinements may take a back seat to the chronic underinvestment that has left systems including the New York subway and Amtrak an increasingly unsafe and inefficient mess.