Cal. Pub. Util. Code § 130405

The revenues from the taxes imposed pursuant to this article may be allocated by the commission for public transportation purposes, including, but not limited to, construction, maintenance, and operation of streets, roads, and highways, and the construction and maintenance of public transit systems, including exclusive public mass transit guideway systems, available now or hereafter. The revenues may also be used for improvements to the state highway system in the manner otherwise provided by law. However, the revenues shall not be allocated for transit operations.