For the purposes of this chapter, “trail” or “path” means a public way constructed primarily for and open to pedestrians, equestrians, or bicyclists, or any combination thereof, other than a sidewalk constructed as a part of a city street or county road for the exclusive use of pedestrians. The term “trail” or “path” also includes a widened shoulder of a highway, street, or road when the extra shoulder width is constructed to accommodate bicyclists consistent with a comprehensive plan or master plan for bicycle trails or paths adopted by a state or local governmental authority either prior to such construction or prior to January 1, 1980.