CA SB909

Authorizes emergency vehicles to be equipped with a "Hi-Lo" audible warning sound that alternates between fixed high and low frequencies, in addition to existing siren requirements.

Restricts Hi-Lo use solely to notifying the public of an immediate need to evacuate in case of emergency.

Clarifies that Hi-Lo is not a substitute for a siren when sounding a siren is reasonably necessary under Vehicle Code Section 21055.

Requires the Department of the California Highway Patrol to establish technical requirements for Hi-Lo warning sounds.

Took effect immediately upon Governor approval on September 29, 2020, as an urgency statute.