I can see through the road in my custom map

I'm working on a custom map. I wanted to import the roads from other maps into my map. What I did was for example: I copied al the files from the road file. I pasted them all in my custom road map. I opent the material.cs file. I copied all the text and added this under the text from the material.cs that was in my files. I also did this with the terrain. My problem now is that I can see through the road as seen in the picture that I added. Can somebody help me with this.