Guard lines shall be established by the warden, superintendent, or his designated representative in charge at the various state or county correctional institutions in the same manner that land lines are established, except that, at each corner of the lines, signs must be used on which shall be plainly stamped or written: "Guard line of ________." Signs shall also be placed at all entrances and exits for vehicles and pedestrians at the institutions and at such intervals along the guard lines as will reasonably place all persons approaching the guard lines on notice of the location of the institutions.