California Code, Streets and Highways Code - SHC § 149

The department may construct exclusive or preferential lanes for buses only or for buses and other high-occupancy vehicles, and may authorize or permit such exclusive or preferential use of designated lanes on existing highways that are part of the State Highway System.  Prior to constructing such lanes, the department shall conduct competent engineering estimates of the effect of such lanes on safety, congestion, and highway capacity.

To the extent they are available, the department may apply for and use federal aid funds appropriated for the design, construction, and use of such exclusive or preferential lanes, but may also use other State Highway Account funds, including other federal aid funds, for those purposes where proper and desirable.

This section shall be known and may be cited as the Carrell Act.