They have one very important purpose: Much like stop signs, they provide blind and visually impaired people with tactile and visual cues that a hazard is in their line of travel; that is, they are nearing the end of a sidewalk and about to enter a street, or nearing the edge of a rail platform. The bumps provide the tactile warning and the bright yellow color provides the visual warning.

"The Pasadena Accessibility and Disability Commission is educating the public about truncated domes because there has been so much guessing about their function," said Commission Chair Donna Pomerantz, who is also president of the San Gabriel Valley Chapter of California Council of the Blind and a member of the organization’s state board.

The Americans with Disabilities Act (ADA) and the state building code require a pattern of truncated domes at the end of light rail platforms and on new curb ramps at street corners.

Truncated domes are being installed along with curb ramps throughout Pasadena by the city’s Public Works Department.

For more information, call 626-744-4782.