how to make road like tample run 2

It's a procedural road. I guess it's done by chunks of about 15 meters. Each of them can be straight, turn left, right or both. If straight, it can be normal, or with a hole / tree / fire etc. It's just about managing assets correclty.

Note : Start smaller, you can't just go ahead with a game with a relatively complex mechanism like that.

You can use "EasyRoads3D" - Road systems for Unity http://www.unityterraintools.com/tools.php Its very simple,you can modify texture or use your own.

I found this a while ago: http://8bitmemories.blogspot.nl/2011/10/procedural-track-generation-in-unity3d.html

From the article:

"This post is basically how to generate a procedural/dynamic road or a track at run time in Unity3D."