California Code, Streets and Highways Code - SHC § 2176

From funds appropriated for such purposes, the department may undertake a program to provide express bus service between Stockton and a station of the San Francisco Bay Area Rapid Transit District selected by the department and the district or between Stockton and Sacramento. The service shall be provided by operators, as defined in Section 99210 of the Public Utilities Code, or by passenger stage corporations, as defined in Section 226 of the Public Utilities Code.