Blocking of appraoch road of my house.

I am from hill side and houses here are build above and below the road . My house is build at side of the road and its above like 30 ft from the governemnt road. My neighbour house is also build that way in adjacent to mine. To have vehicle access at the front of my house, I built an approach road with due permission from concerned authority 10 years ago. The appraoch road is around 50 ft long with elevated from the main road reserve. Problem is that this appraoch road passes from the front side of my neighbour. Till 10 years the neighbour had no problem but recently one of my neighbour sons is having vertical extension of his house. He keeps the materials at the middle of this appraoch road and blocks my way . On asking him to move the materials he has been saying that the approach road is in front of his house so he will not move his material. On contrary he says that he will only allow the access from walking and not let vehicles run at front of his house. The appraoch raod I made falls under road reserve . It's just that this appraoch road shares boundry at front side of his house. What legal measures can I take on this ???