California Code, Public Utilities Code - PUC § 7702

The Department of Transportation, in cooperation with the commission and other affected state and local agencies, shall perform the duties required by the act in developing, promoting, supervising, and supporting safe, adequate, and efficient rail transportation services;  maintaining adequate programs of investigation, research, promotion, and development, with provisions for public participation;  and shall take all practicable steps to improve transportation safety and to reduce transportation-related energy utilization and pollution.  It is not the intent of this section to diminish in any respect the authority and responsibility of the commission.  The department shall work in close cooperation with the commission in carrying out the duties imposed upon it under this chapter.