[§291C-51]  Driving on divided highways. 
Whenever any highway has been divided into two or more roadways by leaving an
intervening space or by a physical barrier or clearly indicated dividing
section so constructed as to impede vehicular traffic, every vehicle shall be
driven only upon the right-hand roadway unless directed or permitted to use
another roadway by official traffic-control devices or police officers.  No
vehicle shall be driven over, across, or within any such dividing space,
barrier, or section, except through an opening in such physical barrier or
dividing section or space or at a cross-over or intersection as established,
unless specifically prohibited by public authority. [L 1971, c 150, pt of §1]