(a) Local authorities in their respective jurisdictions shall place and maintain such traffic-control devices upon highways under their jurisdiction as they may deem necessary to indicate and to carry out the provisions of this act¹ or local traffic ordinances or to regulate, warn or guide traffic. All such traffic-control devices hereafter erected shall conform to the state manual and specifications.

(b) Local authorities in exercising those functions referred to in the preceding paragraph with regard to streets and highways which are a continuation of state or federal numbered highways shall be subject to the direction and control of the State Highway Commission.