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Glossary
 
Passive pedestrian detection Description
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.
Detail of APS at midblock crossing in Australia. Sign reads “push button then wait on red mat.” This midblock crossing has sensors in a specific area of the sidewalk. A red mat area is labeled "Push Button then Wait Here."

How used
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.

References
MUTCD 4E.08

Draft Public Rights-of-Way Accessibility Guidelines 2021.3.4 Optional Features

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Example of passive pedestrian detection

PUFFIN crossings
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
  • Pressure mats with piezo-electric sensors, infrared or microwave detectors mounted on the signal pole, or
  • Video cameras serving remote sensor software.
How used
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:
  • Pedestrian presses a push button to actuate the Walk interval,
  • Detectors confirm the presence of pedestrians standing near the crossing, then
  • If the pedestrian leaves before the onset of the Walk interval, the call for the pedestrian phase is canceled.
PUFFIN crosswalk detectors
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:
  • A preset extension is added to the pedestrian clearance interval;
  • Late-starting or slow-moving pedestrians have more time to clear the intersection before vehicular traffic resumes; and
  • Driver waiting time is reduced if the pedestrian crosses in a gap in traffic instead of waiting for the pedestrian phase.
In Adelaide, Australia, installation of passive pedestrian detection in the crosswalk, for extending crossing time, is now standard at intersections where there is a newly installed APS.

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