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Bicycles/Pedestrians

Safety Toolbox: Engineering


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Automatic pedestrian detection

   
Pedestrians are detected at the curbside and/or in a pedestrian crossing by means other than those requiring a physical response by pedestrians. Most applications use either infrared or microwave technology.
objective To alert drivers of a pedestrian crossing the street at locations with activated beacons or to trigger pedestrian signals. It is also used to extend pedestrian intervals at signalized intersections if pedestrians are detected in the crosswalk.
applications Where there is a need to improve warning signs and crosswalks. At locations with flashing beacons, in-pavement flashers or pedestrian signals.
target population All Pedestrians, Motorists
crash type Pedestrian R/W Violation-Intersection, Pedestrian R/W Violation-Non-Intersection, Pedestrian Violation-Non-Intersection, Pedestrian Violation-Intersection, Traffic Signals and Signs
advantages
  • Devices are activated without relying on pedestrians to push a button.
disadvantages
  • Installation costs and false calls.
  • At uncontrolled crossings, visually impaired pedestrians need to be provided a way to identify where the detection area is located; at signalized intersections, signals must include accessible pedestrian signals for people with visual impairments. A locator tone is also needed to guide visually impaired pedestrians to the detection zone.
pointers Pedestrian detection technology still produces false calls.  Younger pedestrians may speed through the crosswalk before beacons or signals are activated.  However, passive detection may induce more cautious behavior from pedestrians as they may not be aware that the flasher, beacon, or in-pavement lights have been triggered.  If they feel as though they do not have an added degree of protection, they may behave more cautiously as they proceed through the crossing.
cost Varies, $500-$1,000 per sensor for microwave and infrared sensors, $15,000- $25,000 per camera sensor.
responsibility Public Works Department
further reading

Hughes, R., H. Huang, C. Zegeer, and M. Cynecki. Evaluation of Automated Detection at Signalized Intersections. Washington, DC: US DOT, FHWA, February 2000.

examples City of Los Angeles, Department of Transportation, Traffic Division
related tools Accessible Pedestrian Signals, Educational Signs for Pedestrian Signal Indications, Pedestrian Signals, Countdown Signals, Mid-block Signalized Crossings, Pedestrian Signals at Uncontrolled or Partially-Controlled Intersections, In-Roadway Warning Lights at Crosswalks, Wheelchair Detection

Index: alphabetical / cost / crash type / target population

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