California Code, Public Utilities Code - PUC § 99565

(1) The internal and occupational community of interest among the employees, including, but not limited to, the extent to which they perform functionally related services or work toward established common goals, the history of employee representation with the employer, the extent to which the employees belong to the same employee organization, the extent to which the employees have common skills, working conditions, job duties, or similar educational or training requirements, and the extent to which the employees have common supervision.

(2) The effect that the projected unit will have on the meet and confer relationships, emphasizing the availability and authority of employer representatives to deal effectively with employee organizations representing the unit, and taking into account factors such as work location, the numerical size of the unit, the relationship of the unit to organizational patterns of the transit district employer, and the effect on the existing classification structure or existing classification schematic of dividing a single class or single classification schematic among two or more units.

(3) The effect of the proposed unit on efficient operations of the employer and the compatibility of the unit with the responsibility of the transit district employer and its employees to serve the public.

(4) The number of employees and classifications in a proposed unit, and its effect on the operations of the employer, on the objectives of providing the employees the right to effective representation, and on the meet and confer relationship.

(5) The impact on the meet and confer relationship created by fragmentation of employee groups or any proliferation of units among the employees of the employer.