Common Problems Arising in the Installation of Accessible Pedestrian Signals

Issue 12: Audible beaconing

Audible beaconing -- providing a louder audible WALK signal in order to provide directional guidance to pedestrians who are blind -- is not needed at all intersections or during every pedestrian phase. If installed at inappropriate locations, or incorrectly adjusted, audible beaconing can provide confusing or even dangerous information. 

In the pedhead-mounted APS models installed in the US over the past 30 years, sounds were broadcast simultaneously from overhead speakers at each end of the crosswalk and at two parallel crosswalks at an intersection. Research now shows that pedestrians are not able to use the signal for directional information.¹⁴

Even with today’s newer technologies, audible beaconing (or a too-loud signal volume) from an APS at a ‘porkchop’ island with a channelized right turn lane may lead a pedestrian who is blind to cross the channelized turn lane, thinking it is signalized after hearing the audible WALK indication. And at locations where two parallel crosswalks are timed separately, such as locations with split phasing, a loud signal can lead a pedestrian to begin crossing with the wrong crossing indication.

Remedy: New types of APS allow calling a louder signal by holding the pushbutton in for more than one second, so audible beaconing is a feature that can be called ‘on request’. This allows a pedestrian who is blind to decide when a louder signal might be helpful and limits the impact of sound on the neighborhood.

Proposed MUTCD has recommendations for audible beaconing in section 4E.06. 

Recent research has shown that a louder locator tone during the flashing DON’T WALK, from a speaker at the opposite end of the crosswalk from the pushbutton where audible beaconing was requested, improves performance in ‘ending within the crosswalk.^’15 

^14. Wall, et al., 2004.

¹⁵. Scott, A.C., Barlow, J. M., Bentzen, B.L., Bond, T. and Gubbe, D. (in press) Accessible Pedestrian Signals at complex intersections: Effects on blind pedestrians. Transportation Research Record: Journal of the Transportation Research Board. 2008.