I agree with Mr. K; users of a ROW (in my states, CA and OR, right-of-way and road/access easement terms were used interchangeably) would seem to have the right to keep it open and passable.
Is there some problem created by the snowplowing, or some reason that you question their plowing? (It could well be neighborly concern on their part if they plow out to the public road). Damage to the condition of the surface?? Resulting snowbanks blocking you??

