Easement over government property ( reserve site)

I have an ancestral property in Tamilnadu, which was totally 1.50 acres, my grandfather sold 50 cents land 20 yrs ago and now the remaining 1acre is there. my opposite property owner sold his land around the same time 20 yrs ago and for DTCP approval he made a road between my land and his., but he also left a strip of land on my side of the road as "reserved site"..so for me to access the road, i need to cross the "reserved site" and other 3 sides are covered with buildings. when i tried to rent out my property for commercial purpose, the neighbours of the land are preventing it saying that i cannot use "reserved site" for road and it can only be used for parks and other activities. since i do not have any other way to access the land, what is the permanent legal solution possible and how much time it will take to get a permanent easement. [===== House buildings ====] [Neighbour land X acre] [ == 20 ftROAD == ] [Reserved site ] [ My Land 1 acre] [=House buildings=] [===== House buildings ====]