As specified in MUTCD (Manual on Uniform Traffic Control Devices) Chapter 4N and in California MUTCD Chapter 4N, our inpavement lights warn motorists that pedestrians are in the crosswalk. They are activated by a pedestrian pressing a push button at either curb. Each fixture projects a rapidly flashing yellow light that is clearly visible in daylight or under the worst weather conditions.
A two-lane road, 24 feet wide, would have three fixtures embedded on each side of the crosswalk. Four-lane roads typically use ten fixtures.