Locator tones for pedestrian signals

The two primary problems experienced by visually impaired persons at pedestrian-actuated intersections are determining whether there is a push-button and locating the push button. Many countries use accessible pedestrian signals much more widely than has been done in the United States, and a number of these - including Australia, Hong Kong, Sweden, Denmark, Germany, Belgium, and Austria-routinely require the use of a locator tone. Typically emanating from the push-button housing, a push-button locator tone indicates to pedestrians that they are expected to push a button to request a pedestrian phase. It enables visually impaired pedestrians to locate the push button quickly and efficiently. Research was undertaken to determine the effect of locator tone repetition rate on efficiency of pedestrians' location of the push-button pole. Repetition rates of 1.0 and 1.5 Hz resulted in equal pole location speed, faster than that for the 0.5 Hz repetition rate, and were preferred over the 0.5 Hz repetition rate. Locator tones 2 dB above ambient sound resulted in faster pole location than did tones 5 dB and 10 dB above ambient sound. Push-button locator tones should have a standardized repetition rate between 1.0 Hz and 1.2 Hz so that is may be ensured that visually impaired pedestrians can efficiently locate push buttons. Locator tones need be no more than 5 dB louder than ambient traffic sound.