Gov. Code, § 840.4

(a) A public employee had actual notice of a dangerous condition within the meaning of subdivision (b) of Section 840.2 if he had actual personal knowledge of the existence of the condition and knew or should have known of its dangerous character.

(b) A public employee had constructive notice of a dangerous condition within the meaning of subdivision (b) of Section 840.2 only if the plaintiff establishes (1) that the public employee had the authority and it was his responsibility as a public employee to inspect the property of the public entity or to see that inspections were made to determine whether dangerous conditions existed in the public property, (2) that the funds and other means for making such inspections or for seeing that such inspections were made were immediately available to the public employee, and (3) that the dangerous condition had existed for such a period of time and was of such an obvious nature that the public employee, in the exercise of his authority and responsibility with due care, should have discovered the condition and its dangerous character.