Section 25257.5 Of Article 7. Flashing And Colored Lights From California Vehicle Code >> Division 12. >> Chapter 2. >> Article 7.

. To warn other motorists or pedestrians on a roadway during a backing maneuver, the operator of a schoolbus may flash turn signal lamps if the front turn signal lamps at each side are flashed simultaneously and the rear signal lamps at each side are flashed simultaneously.