(a) A public entity had actual notice of a dangerous condition within the meaning of subdivision (b) of Section 835 if it had actual knowledge of the existence of the condition and knew or should have known of its dangerous character.
(b) A public entity had constructive notice of a dangerous condition within the meaning of subdivision (b) of Section 835 only if the plaintiff establishes that the condition had existed for such a period of time and was of such an obvious nature that the public entity, in the exercise of due care, should have discovered the condition and its dangerous character. On the issue of due care, admissible evidence includes but is not limited to evidence as to:
(1) Whether the existence of the condition and its dangerous character would have been discovered by an inspection system that was reasonably adequate (considering the practicability and cost of inspection weighed against the likelihood and magnitude of the potential danger to which failure to inspect would give rise) to inform the public entity whether the property was safe for the use or uses for which the public entity used or intended others to use the public property and for uses that the public entity actually knew others were making of the public property or adjacent property.
(2) Whether the public entity maintained and operated such an inspection system with due care and did not discover the condition.