With the idea that the standard allotment of time may not be enough for some people to make it across the street, the city of Cologne, Germany has installed two CMOS-camera based video pedestrian light systems that will recognize waiting pedestrians and extend the green phase if there are still people crossing after the standard time allocation.
The “safe walk” system from Siemens is the first of the two systems, and is made up of two cameras from FLIR Intelligent Transportation Systems. A stereo camera with two CMOS 1/3-inch black and white sensors and 3 mm lenses and a frame rate of 25 FP/s is mounted 3.5 meters above to ground to cover an area of 3m x 4m. The system observes the waiting area and recognizes objects with a height above 50 cm in order to eliminate shading and other distractions. The system’s algorithm also recognizes the moving direction of pedestrians and can only sort out people who pass through the detection area. This way, only people waiting at the light trigger a signal to the control unit to begin the “green phase,’ according to a Novus Light article.
The second system, called the “C-walk” system, recognizes when people have crossed the street in the minimum green period and sends a signal to the Siemens control unit in order to extend the time. C-walk is made up of a Traficon (FLIR) color CMOS camera with an integrated detector board unit and a ¼-inch sensor that delivers up to 25fps with a camera sensor of 640 x 480 pixels. CMOS sensors were chosen because in traffic detection applications, they deliver more reliable images than CCD sensors and have a higher resistance to blooming from auto headlights at night, according to Dr. Christoph Roth, product manager in the Road and City Mobility department at the Siemens Infrastructure & Cities Sector.
View the Novus Light article on video-controlled pedestrian crosswalks.
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