It is unclear from your statement whether you own the 20 foot access or only have an easement. If you own the property outright and it is not subject to an easement in this other person I would suggest you take your deed and survey, if any, to the state troopers.
If on the other hand you either own the 20 foot access and it is subject to an easement or the neighbor or someone else owns the property subject to your easement than you are likly to need an attorney. In that case take all your paperwork to a real estate attorney for review of your options.
My answer to your question is for general purposes only and does not establish an attorney-client relationship,
If I understand your statement, a neighbor who borders on your roadway is using all or some of it for his own possession and enjoyment. First you must confirm that the land he is using is actually owned by you, which requires an analysis of your deed and possibly the use of a land surveyor. Note that there is a difference between you having an easement (a legally permissible use of someone else's property to be able to access your property which might otherwise be landlocked) and outright ownership. If you in fact own the roadway-land, then you have to watch out because this person is essentially, in an open and hostile manner, making use and possession of your property against your wishes. If he continues to do this, or has been doing this, for 10+ years you face a claim of "adverse possession", which ultimately makes the property his ; in otherwords, you would lose possession of that portion of the roadway that he "adversely possesses(ed). It may be necessary for you to take the person to court to have him evicted off of the roadway-land, which you should do as soon as possible since he is not leaving on his own. See a real estate lawyer a.s.a.p.