Conform Compound Object in Autodesk 3Ds Max

Conform is s very special kind of compound object which help us to put an object's vertices implant over another object's surface. First create a plane with high value of subdivisions. Then put a noise modifier on it and make the surface uneven or rough.

Now create a spline from the top view and make it renderable in viewport and also for the render output. Change the type to rectangular so that it will look like a road. Now next step is very inportant. you need to understand which object is the wrap and which one is the "wrap-to" object. Here the road like object created through spline is the wrap object and, the uneven surface is the "wrap-to" object.

Before proceeding convert the line to editable poly. Then click on the conform from the compound object list in the create tab. Then select the wrap-to object which is the plane or the terrain object. Use active viewport option for the projection and your road will be projected according to the surface of the plane. You can again convert the road to editable poly or you use edit poly modifier and make the face extrude modifier to give that road a thickness.