What is the maximum sound level (in dB) recommended for traffic signal audible alerts?

The recommended maximum sound level for traffic signal audible alerts is typically around 85 dB. This level is considered effective for ensuring that the alerts can be heard clearly by pedestrians, including those who may have hearing impairments, without being overwhelmingly loud or causing discomfort.

Standards and guidelines for traffic management prioritize both visibility and audibility of signals to enhance safety for all users, particularly at busy intersections. Setting the alert volume around 85 dB strikes a balance where the sound is loud enough to be distinctive in urban environments, yet it helps to mitigate any potential auditory disturbances for nearby residents or other pedestrians.

Levels above this range, such as 90 dB or 100 dB, might increase the risk of hearing damage to individuals exposed to them over time and could lead to complaints from the community. Levels lower than 75 dB may not be effective, especially in locations with background noise from traffic and other urban sounds that could drown out the alerts. Thus, the choice of around 85 dB is optimal for the purpose of traffic signal audible alerts.