Failure Analysis of Corroded Pedestrian Safety Systems

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Mike Hurley


Campbell Pedestrian Safety systems produces pushbuttons for crosswalks. APS systems like those developed by Campbell give auditory cues to assist blind and vision impaired pedestrians to safely cross. The bodies of these pushbuttons are composed of two layers, housing the motor, circuitry, and a chamber where the button itself is depressed. Failure was observed when six pushbuttons in five locations stopped responding to touch. One failed in Kansas City, Kansas, while the five others failed within a few miles of each other in the Minneapolis-St.Paul region. Buttons were reportedly “packed” with a white powder, and others were heavy with water when received by Campbell. The nature of the failure was clearly corrosion, but a thorough analysis of where and how failure occurred would be the best way to prevent it in the future. Samples were disassembled and extensively photographed, with powders collected for analysis. Speculation was made about the causes of the corrosion and steps that could prevent it in the future.

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