They put up traffic control and warning signs and once you enter you must go through the check point. If you attempt to avoid the check point you will be stopped and cited for disobeying a lawful traffic control checkpoint. You can look it up.
The last couple checkpoints that I've seen in Walker were at the old Winn Dixie. They put units at the three road leading off 447 down to I-12 so you couldn't turn off.