Clearance Interval tones Description A tone or other message sounds during the pedestrian clearance interval, at a different rate, tone, or with a different speech message, than the WALK interval indicator. This is not the same as the APS reverting to the locator tone during the flashing DON'T WALK and DON'T WALK interval.
Clearance interval information is sometimes provided by APS in Japan and in some parts of Canada.
In Japan, a variety of alternatives are available including a European emergency vehicle "ba-boo" sound, and various melodies.
In Canada, it may be provided by a tone that repeats at a faster rate than the WALK signal. For example, if the WALK signal is a "cuckoo" at 1 time per second, during the clearance interval the "cuckoo" is sounded 2 times per second.
Additional information Advantages:
Lets pedestrians who are visually impaired who have begun to cross the street know that the clearance interval prevails, that is, that they do not yet have to fear the onset of perpendicular traffic; and
Because it comes from loudspeakers at both ends of crosswalks, they may be able to home in on it as they complete their crossing.
The sound is relatively loud, possibly masking the sound of critical traffic movement; and
The clearance interval sound might be mistaken for the WALK signal.
It is particularly important that pedestrians who are blind not mistake a clearance interval signal for a WALK signal, as they could begin crossing late in the clearance interval when they would not have enough time to complete crossing before the onset of perpendicular traffic.
This feature is not currently used in the US and is not recommended due
to the potential confusion of the Walk interval with the clearance interval.