Audible beaconing is the use of an audible signal in such a way that blind pedestrians can home in on the signal coming from the target corner as they cross the street.
The PROWAAC report, Building a True Community defined an audible beacon as: "a permanently fixed source emitting sound for directional orientation" (PROWAAC 2001). The MUTCD defines audible beaconing as “the use of an audible signal in such a way that pedestrians with visual disabilities can home in on the signal that is located on the far end of the crosswalk as they cross the street.”(2009, Section 4E.13, P4)
MUTCD requires that the audible beaconing be called up by special actuation, rather than the APS functioning in the louder mode all the time.
The recommended form of special actuation is an extended button press (holding the pushbutton in for over one second).
A minority of crosswalks require audible beaconing, in which the sound source provides directional orientation. Where audible beaconing is activated, the volume of the WALK indication and the subsequent locator tone, or just the locator tone during the called pedestrian phase is increased and may be operated in one of the following ways:
- Increased sound comes from the far end of the crosswalk, as pedestrians cross the street
- The louder locator tone comes from both ends of the crosswalk, or
- the louder locator tone is broadcast from an additional pedhead mounted speaker aimed at the center of the crosswalk
Audible beaconing speakers must be oriented in line with the relevant crosswalk.
- If the speaker is not carefully oriented, the signal may give ambiguous information about which street has the WALK interval, and ambiguous information for traveling straight across the street.
- Beaconing is enhanced by the presence of a locator tone that users can home in on as they approach the destination corner, island or median having an accessible pushbutton.
See Chapter 6, Designing Installations, for additional recommendations regarding audible beaconing.
MUTCD 4E.09 (2003) states: "The audible tone(s) may be made louder (up to a maximum of 89 dBA) by holding down the pushbutton for a minimum of 3 seconds. The louder audible tone(s) may also alternate back and forth across the crosswalk, thus providing optimal directional information."
When to use
Not all crosswalks at an intersection need beaconing. Audible beaconing can actually cause confusion if used at all crosswalks at some intersections. Audible beaconing is probably not appropriate at locations with channelized turns or split phasing, due to the possibility of the signal being heard at the wrong crosswalk.
Audible beaconing should only be considered at:
- Crosswalks longer than 70 feet, unless they are divided by a median that has another APS with a locator tone
- Crosswalks that are skewed
- Intersections with irregular geometry such as five or more legs
- Crosswalks where audible beaconing is requested by an individual with visual disabilities
- Other locations where a study indicates audible beaconing would be beneficial
How used by pedestrians who are blind or who have low vision
Pedestrians may be able to home in on the signal to assist with maintaining alignment while crossing the street.
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