Why does a ‘machine gun’ tell us it’s safe to cross the street?

Brig props today to Richard Chin of the Pioneer Press who answers a question we’ve had since the Green Line started running in downtown Saint Paul. What’s the story with that godawful machine gun sound signalling that it’s OK to cross the street?

The stern male voice that says “wait” seems to get the message across OK. Why can’t there be a more reasonable way to tell people to cross the street without making us feel we’re doing so at gunpoint?

The machines once used bird calls to signal the “walk” light to the visually impaired but, Chin says, people got the sound confused with real birds (this was a problem in Canada, too, which adopted the “Canadian Melody” instead). No chance of getting the current sound mistaken for real gunshots, apparently.

But studies comparing recorded voices and other audible signals, including chirps, cuckoos, clicks and a four-tone melody, found that the so-called “rapid tick” produced “the fastest and most accurate responses regarding which crosswalk has the ‘Walk” indication,” according to “Accessible Pedestrian Signals: A Guide to Best Practices,” produced in 2007 by the National Cooperative Highway Research Program.

The eight-tick-per-second noise, frequently described as sounding like a machine gun, has since been adopted in the latest federal and Minnesota manuals for traffic control devices.

That’s why St. Paul has been using rapid tick as it installs APS devices on crosswalks in effort to comply with the federal Americans with Disabilities Act.

Critics says another problem with the noise is it doesn’t provide a countdown to give people an idea of how long they have to cross.