Whenever the traffic engineer determines that traffic congestion or traffic hazard of any emergency nature is likely to result from the operation, stopping, standing, or parking of vehicles during the holding of public or private assemblages, gatherings, or functions, or during the construction, alteration, repair, or improvement of any highway, or for any other reason, he may place or cause to be placed, temporary signs prohibiting the operation, stopping, standing, or parking of vehicles during the existence of such emergency. (Prior code § 67710)