California Code, Government Code - GOV § 831.3

Neither a public entity nor a public employee is liable for any injury occurring on account of the grading or the performance of other maintenance or repair on or reconstruction or replacement of any road which has not officially been accepted as a part of the road system under the jurisdiction of the public entity if the grading, maintenance, repair, or reconstruction or replacement is performed with reasonable care and leaves the road in no more dangerous or unsafe condition than it was before the work commenced. No act of grading, maintenance, repair, or reconstruction or replacement within the meaning of this section shall be deemed to give rise to any duty of the public entity to continue any grading, maintenance, repair, or reconstruction or replacement on any road not a part of the road system under the public entity's jurisdiction. As used in this section “reconstruction or replacement” means reconstruction or replacement performed pursuant to Article 3 (commencing with Section 1160) of Chapter 4 of Division 2 of the Streets and Highways Code.