California Code, Streets and Highways Code - SHC § 2101

(a) The research, planning, construction, improvement, maintenance, and operation of public streets and highways, including their related public facilities for nonmotorized traffic, the mitigation of their environmental effects, the payment for property taken or damaged for those purposes, and the administrative costs necessarily incurred in the foregoing purposes.For purposes of this subdivision, “maintenance of public streets and highways” shall include maintenance or removal of cattle guards within the right-of-way of a county highway.

(b) The research and planning for exclusive public mass transit guideways, their related fixed facilities, the payment for property taken or damaged for those purposes, and the administrative costs necessarily incurred in the foregoing purposes.

(c) The construction and improvement of exclusive public mass transit guideways, including their related fixed facilities, the mitigation of their environmental effects, the payment for property taken or damaged for those purposes, the administrative costs necessarily incurred in the foregoing purposes, and the maintenance of the structures and the immediate right-of-way for the public mass transit guideways, but excluding the maintenance and operating costs for mass transit power systems and mass transit passenger facilities, vehicles, equipment, and services, in any area where the voters have approved a proposition pursuant to Section 4 of Article XIX of the California Constitution.

(d) The payment of principal and interest on voter-approved bonds issued for the purposes specified in subdivision (c).