I would suggest that you seek help from a real estate attorney in your area as soon as you can.  Bring your deed with you.  There may be an easement in the deed as written and then the attorney will know what to do about it.  If not then there may be an action that you can bring as to the use of the road all this time and an implied easement if the law allows.  But look: this is the government and sometimes you can not fight and win.  So it may pay to ask the attorney about other options but I would not just move the barricade.  Good luck.