The type of APS that has been most commonly installed in the U.S. has a speaker mounted inside or in the vicinity of the pedhead.
Typical functioning of pedhead-mounted devices:
Sound, usually a cuckoo, chirp, or beep, is emitted during the Walk interval only
Not available, except as a separate component sold by one manufacturer
Not typically available; some manufacturers sell the locator tone speakers as a separate component
As typically installed in the US, pedhead-mounted APS are attached to the pedestrian signal head and aimed toward the opposite curb.
While pedhead-mounted APS have typically been installed with volume adjusted to be heard across the street, tone volume and speaker alignment can be adjusted so WALK indications are audible only from the vicinity of the waiting area for the associated crosswalk. In most installations, louder signals are a disadvantage. Loud WALK indications coming simultaneously from both ends of a crosswalk are of little or no value in providing beaconing information.
Additional options include:
Speakers must be carefully located so that they are above the end of the crosswalk they signal, or they provide ambiguous information about which crosswalk has the Walk interval.
Devices should be responsive to ambient sound (automatic volume adjustment feature); some devices sold in the US are not.
Draft Public Rights-of-Way Accessibility Guidelines require locator tones at pushbuttons.
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This site was developed under the sponsorship of the National Cooperative Highway Research Program.