Passive pedestrian detection is available to call the WALK indication and can extend the clearance interval. Authors are not aware of US installations that include audible signals as well as visual signals, but this technology is known to be in use in the United Kingdom, Australia, New Zealand and the Netherlands.
One pushbutton integrated APS provides the option of triggering the pushbutton locator tone through sensors (piezo-electric, infrared, or microwave) when the pedestrian enters the detection zone.
While passive detection of pedestrians for activating the locator tone may be helpful in reducing noise near the intersections, pedestrians who are blind may not be approaching the crosswalk or intersection within the detection zone. They also may not know about it unless they are familiar with the intersection.
Draft Public Rights-of-Way Accessibility Guidelines 2021.3.4 Optional Features
Example of passive pedestrian detection
An example of passive pedestrian detection technology is the "Pedestrian User-Friendly Intelligent (PUFFIN) crossing in use in England since 1993 (Department of Transport, 1993). PUFFIN crossings employ pedestrian detectors for both the pedestrian waiting area and the crosswalk.
PUFFIN waiting area detectors
Waiting area detectors consist of either
For such detectors to be effective, pedestrians who are visually impaired must be able to locate the pushbutton, the precise waiting area, and the crosswalk.
The following sequence occurs:
Crosswalk detectors are microwave or infrared sensors that respond to pedestrians moving in the crosswalk. As long as a pedestrian is detected in the crosswalk:
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