Accessible Pedestrian Signal Features
Required features of new types of APS include pushbutton locator tones, audible walk indications, vibrotactile walk indications, tactile arrows, and automatic volume adjustment. In addition, there are specific requirements for the location of the pushbuttons and speakers.
Pushbutton locator tones
A pushbutton locator tone is “A repeating sound that informs approaching pedestrians that they are required to push a button to actuate pedestrian timing to receive additional information and that enables pedestrians with visual disabilities to locate the pushbutton.” (MUTCD 2009, Section 4E.12, P3)
The pushbutton locator tone can vary from a click sound to a beep type tone. The repetition rate and length of tone are standardized to repeat once per second and to be a short tone, of less than 0.15 seconds or less. (MUTCD Section 4E.12, P4 ) The volume of the pushbutton locator tone is required to be responsive to ambient sound and audible 6 to 12 feet (2 to 4 meters) from the push button or at the building line, whichever is less (MUTCD Section 4E.12, P6 ).
Audible Walk Indications
APS provide an audible indication of the walk interval.
Rapid tick walk indications
In the US, a rapid tick walk indication is required where the APS can be appropriately located on two separated poles on a corner. Research has found that the rapid tick walk indication results in more accurate and faster recognition and response to the onset of the WALK than other tones or speech walk messages.
Speech walk indications
In a situation where two APS on a corner must be located on the same pole, or less than 10 feet apart, speech walk messages are required. Research found that speech messages resulted in more accurate recognition than two different tones, but not as accurate a response as a single tone from well-located separated poles. When using speech messages, consistent wording is important. Speech messages must begin with the name of the street to be crossed, followed by “Walk sign is on to cross [street name]”. For example, the speech message for the APS for crossing Patton Avenue would say “Patton, walk sign is on the cross Patton. Patton, walk sign is on to cross Patton” during the walk interval.
If speech messages are used, it’s essential that the pedestrian know the name of the street being crossed. An additional feature, a pushbutton information message, is needed on the device to provide street name information to the pedestrian who is unfamiliar with the intersection. When the pushbutton is pushed and held for more than one second during the flashing or steady don’t walk interval, the pushbutton information message provides a message which includes the name of the street controlled by the pushbutton.
Vibrotactile walk indications
A raised (tactile) arrow is required on the pushbutton and provides information to pedestrians who are blind or low vision about which crosswalk is controlled by the pushbutton.
The arrow must visually contrast with its background. The tactile arrow provides confirmation that is similar to the printed sign and arrow which are commonly provided for pedestrians who are sighted. It is important that the arrow points in the direction of travel on the crosswalk, as it indicates which crosswalk is controlled by that pushbutton. Tactile arrows provide general alignment information for all pedestrians.
The arrow is also the part of the APS that vibrates during the WALK interval.
Automatic volume adjustment
APS have automatic volume adjustment and are automatically responsive to ambient (background) sound. The volume of the locator tone and the walk indication will be louder when vehicle and other noise at an intersection is high (as during traffic surge or when a truck is passing) and quieter when background noise volume is lower (night-time hours or lull in traffic). The volume adjustment responds almost immediately to sounds at the intersection so the volume may change during a signal cycle as vehicles pass by.
For detailed information about APS features and the use of features by pedestrians who are blind or who have low vision, see Chapter 4 of the APS Guide.