Passive pedestrian detection
Figure 4-10. Detail of APS at midblock crossing in Australia. Sign reads "Push button then wait on red mat."
Passive pedestrian detection is sometimes used to call the pedestrian phase and can extend the clearance interval. The authors are not aware of U.S. installations of passive detection that include audible signals as well as visual signals, but the combination of passive pedestrian detection and audible signals is being used in the United Kingdom, Australia, New Zealand and the Netherlands.
One available APS provides the option of triggering the pushbutton locator tone through sensors (piezo-electric, infrared, or microwave) when a pedestrian enters the detection zone. If a pedestrian is not detected, the locator tone is silent.
Figure 4-11. This midblock crossing has sensors in a specific area of the sidewalk. A red mat area is labeled "Push button then wait here."
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. 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.
MUTCD 4E.09 "Accessible pedestrian signal detectors may be pushbuttons or passive detection devices."
How used by pedestrians who are blind or who have low vision
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.
Pedestrians who are blind may also not stand or travel in the exact waiting or crossing area to trigger passive detection for the WALK or to extend the clearance interval.
[ back to top ]