Passive Pedestrian Detection at Unsignalized Crossings

The city of Portland, Oregon, is researching ways to provide safe unsignalized crossings for pedestrians. A concept that shows promise is known as passive pedestrian detection. Passive pedestrian detection is the detection of pedestrians in a stationary or moving state at the curbside of or in a pedestrian crossing by means other than those requiring physical response by the pedestrian. Research was conducted to find sensor technologies that can be used to passively detect pedestrians. Five technologies were found to be options for this type of detection: passive infrared, ultrasonic, microwave radar, video imaging, and piezometric. Of these five technologies, passive infrared, ultrasonic, and microwave radar were selected for testing. An unbiased selection of sensors was made by using a decision matrix in the form of the quality function deployment method, which also provides a record of sensor information for future research. Preliminary testing was conducted on the sensors to ensure that the detection of pedestrians was possible and to determine sensor operating characteristics. Sensors then went through secondary tests to ensure proper operation at an unsignalized crossing. The secondary test site was retrofitted with reflective pedestrian crossing signs, yellow beacons, Doppler radar, and passive infrared sensors chosen from the preliminary tests. Initial secondary tests have shown promising results for the Doppler radar and especially for the passive infrared sensors. Future applications of passive pedestrian detection in Portland will involve installation of sensors at signalized pedestrian crossings.