No vehicle shall be turned so as to proceed in the opposite direction upon any curve, upon the approach to or near the crest of a grade where such vehicle cannot be seen by the driver of any other vehicle approaching from either direction within five hundred feet, or at any place where such turns are prohibited by signs. No vehicle, except authorized emergency vehicles, shall be turned at any place on a freeway so as to proceed in the opposite direction.
Neb. Rev. Stat. §§ 60-6,160