It is hereby determined upon the basis of an engineering and traffic survey that the prima facie speed limit of twenty five (25) miles per hour is more than is reasonable and safe on the streets set forth in this section, and whereas such streets have grades in excess of ten percent (10%), it is determined and declared that a maximum speed limit of fifteen (15) miles per hour is found appropriate, reasonable and safe to facilitate the orderly movement of traffic on those portions of the streets designated herein:
Carla Ridge between Loma Vista Drive and Schuyler Road.
Hillcrest Road from Doheny Road to the north terminus of Hillcrest Road.
Loma Vista Drive between Castle Place and Evelyn Place.
Summit Drive between San Ysidro Drive and Benedict Canyon Drive. (1962 Code § 3-6.1602)