OPINION — AG — QUESTION: DOES THE COUNTY HAVE THE AUTHORITY TO REGULATE THE MAXIMUM SPEED LIMIT UPON A FEDERAL HIGHWAY WITHIN ITS CORPORATE LIMITS OR JURISDICTION? ANSWER: THE PROVISIONS OF SUCH AUTHORITY MUST BE EXERCISED SOLELY ON THE BASIS OF AN ENGINEERING AND TRAFFIC INVESTIGATION AS PROVIDED IN 47 O.S. 1961, 11-803 [47-11-803] THAT, BEFORE SUCH ALTERATION IN SPEED COULD BE EFFECTIVE THE BOARD OF COUNTY COMMISSIONERS WOULD BE REQUIRED TO SECURE THE APPROVAL OF THE STATE HIGHWAY DEPARTMENT (STATE DEPARTMENT OF TRANSPORTATION) FOR THE REDUCTION OF SPEED TO THAT WHICH IS DEEMED REASONABLE AND SAFE UNDER CONDITIONS FOUND TO EXIST AT THE LOCATION INVOLVED, THAT THEY (THE COMMISSIONERS) MUST ALSO SECURE WRITTEN APPROVAL FROM THE DEPARTMENT OF HIGHWAYS FOR THE SHAPE, SIZE AND TYPE OF SIGN OR TRAFFIC CONTROL SIGNAL DESIRED AND FOR THE LOCATION AT WHICH CONTROL IS INTENDED TO BE PLACED, AND SUCH SIGNS ARE APPROVED MUST BE POSTED AS PROVIDED IN 47 O.S. 1961, 15-102 [47-15-102]. ** NEGATIVE ** CITE: 47 O.S. 1961, 11-803 [47-11-803], 47 O.S. 1961, 1-130 [47-1-130], 47 O.S. 1961, 15-101 [47-15-101], 19 O.S. 1961 339 [19-339], 47 O.S. 1961, 15-102 [47-15-102], 47 O.S. 1961, 15-105 [47-15-105], 47 O.S. 1961, 15-106 [47-15-106] (FLOYD MARTIN)