Official traffic signs at traffic islands, safety zones and grade separations, etc

Local, county and State authorities, with respect to highways under their jurisdiction, may erect and maintain appropriate official traffic signs not inconsistent with the provisions of chapter 4 of Title 39 of the Revised Statutes, on a highway or at an intersection where the movements of traffic are regulated and controlled by traffic islands, traffic circles, channelizing islands, divisional islands, safety zones, grade separations or other physical structures which have been erected by such authority; and such authorities may erect and maintain railroad advance warning signs and other appropriate official traffic signs where any such highway crosses a railroad at grade.