Public access to a road

Sir, there is this road that provides access to more than five households and that has been in use for more than two decades. A person of one of these houses,had purchased part of the entrance,decades ago(as per his claims), about a feet wide on one corner of the approach to this road, for erecting a sign board, to display how to approach his property. Now he says entrance to the road is as per his whims as he can block off the road/impede entrance to the road, by constructing a pole on his side of property. The entrance to this road is just wide enough to allow a four wheeler only. Can a person block access to a road that has been used by the public for a long period of time even if he owns part of the road? He has encroached on a part of my land(constructed a gate pillar) and when asked, pulls up this threat of blocking access, at least to my car, because the road entrance is narrow. What are my options? What are the rights of the public as to access by foot, by vehicles, on such a road? How do I proceed to remove his gate pillar erected in the last two days on my property? Many thanks.