Dynamic passive pedestrian detection (DPPD) has the potential to enhance the operational efficiency and safety of signalized intersections by cancelling unnecessary pedestrian service calls or extending the pedestrian phase to allow a pedestrian to safely finish crossing the street. Researchers examined the accuracy and reliability of two thermal sensors (high and low resolution) and one optical sensor for DPPD at one signalized intersection and one signalized mid-block trail crossing in Washington County, Oregon in the Spring and Fall of 2019. The signalized intersection had crosswalk lengths of 120 feet and 90 feet, and the mid-block location had a street-crossing width of about 70 feet, comprised to two crossings of 30 feet separated by a median. Due to crossing length, two curb zones and two or three crosswalk zones were defined for each crossing in the detection software for individual evaluation, and zones were classified as arriving or departing based on the pedestrian’s travel direction. Video files recorded between March and May 2020 were analyzed to assess the accuracy of the sensors according to the following definitions:
Valid – Pedestrian enters zone, detection is initiated and held continuously until pedestrian leaves, with less than one second of delay in initiating or dropping the call.
Inaccurate – Any of the following detection outcomes were counted as inaccurate:
- Spotty – Pedestrian in the zone while call is dropped and reinstated.
- Dropped – Pedestrian in the zone while call is dropped and not reinstated.
- Held – Pedestrian leaves the zone, but call is held by more than one second.
- Late – Pedestrian enters the zone, but call is initiated late by at least one second.
- Miss – Pedestrian enters and leaves the zone without detection.
Accuracy (percent) = 100 x Valid / (Valid + Inaccurate)
A total of 512 unique crossing observations were recorded, 102 at the signalized intersection and 410 at the mid-block trail crossing.
Volume 8, November 2020
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