Is any guidance provided in the MUTCD for the flashing rate of In-Roadway Warning Lights?
Section 4N.02 states that the flash rate for In-Roadway Warning Lights at crosswalks shall be at least 50, but not more than 60 flash periods per minute. This standard is modified by the option in Section 4N.01 that allows In-Roadway Warning Lights to have a flash rate different from the flash rate of standard beacons. Some varieties of In-Roadway Warning Lights use a “stutter flash” that rapidly pulses the lights during the “on” portion of their on-off cycle. Section 4N.02 further states that the flash rate shall not be between 5 and 30 flashes per second, to avoid frequencies that might cause seizures. Thus, the pulsing during the “on” periods of the light must be at a rate slower than 5 per second or faster than 30 per second. Return to Top Return to Frequently Asked Questions.
