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How do they work?
Accessible Pedestrian Signals are linked to the visual pedestrian signals. The APS advise the blind, visually impaired, and deaf-blind when they have the right-of-way to cross the street at a signalized intersection and in which direction they may cross the intersection.
Two audible tones are used to indicate the direction in which the pedestrian has the right-of-way:
- A cuckoo sound (accompanied by the walking person display) indicates that the pedestrian has the right-of-way in the north/south direction.
- A chirp sound (accompanied by the walking person display) indicates that the pedestrian has the right-of-way in the east/west direction.
At some signals, the APS operates automatically. At other signalized intersections, a pedestrian pushbutton must be pushed and held for at least three seconds. If the button is not held down for at least three seconds, the audible sound will not be activated even though the walking person display appears.
Some signals are equipped with left-turn green arrow phases. During this phase the visual walk is displayed on the non-conflicting side. The audible tones will not come on until the left-turn phase has ended and both visual walk displays are on. This is to avoid pedestrians, who are blind or visually impaired, from mistaking the audible tone on the non-conflicting side for the conflicting side.
In addition to the “cuckoo” and “chirp” sounds, some signals are equipped with a continuous tone called a “locator tone”. This tone is emitted from the pushbuttons to assist pedestrians, who are blind or visually impaired, in locating the pushbuttons. Some pushbuttons are equipped with a raised arrow that points in the direction of travel. This arrow vibrates when the APS sounds are activated.
The APS sounds and locator tones automatically adjust to ambient sound levels. Therefore, during peak traffic conditions, they may sound louder; overnight they drop to their lowest volume level.
Sound samples:
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Sample cuckoo sound