What is considered constructive notice in a motor vehicle accident case?

imputed if it can be shown that an obvious danger existed for an adequate period of time before the accident to have permitted the state employees, in the exercise of due care, to discover and remedy the situation had they been operating under a reasonable plan of inspection. . . . [I]n determining whether there is constructive notice, the method of inspection has been held to be secondary. The primary and indispensable element of constructive notice is a showing that the obvious condition existed a sufficient period of time before the accident." (State v. Superior Court of San Mateo County (1968) 263 Cal.App.2d 396, 400.)