Audible beaconing
Description
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). MUTCD and Draft PROWAG recommendations are that the 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).
Additional information
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 during the called pedestrian phase is increased and may be operated in one of the following ways:
- Increased sound comes from all speakers for the crossing, or
- a louder locator tone comes from the speaker at the far end of the crosswalk during the pedestrian phase, or
- the louder audible WALK indication and louder locator tone are broadcast from an additional pedhead mounted speaker aimed at the center of the crosswalk, or
- the audible WALK indication alternates back and forth from speakers at each end 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.
Reference
Draft PROWAG does not specifically mention audible beaconing, but provides for optional features in 1106.3.4.
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."
Revisions have been made in meetings of NCUTCD and are expected to be included in the 2009 revision of the MUTCD. Recommendations are that the 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).
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.