Whenever it is determined on the basis of an engineering and traffic investigation that conditions exist upon a street, road or highway which warrant an increase in the speed permitted by state law, the City Council, subject to the approval of the Secretary of Transportation in cases involving state highways, shall determine and declare a reason-

able and safe maximum speed limit for such street, road or highway, or portion thereof, not to exceed sixty miles per hour. (Ord. 1477 § 2, 1989: Ord. 304 § 37, 1963).