After lots of work on my road system, I finally have a nice terrain-following mesh representing roads/tracks, etc.

The road mesh sits a tiny amount above the terrain but I now need to work out how to blend the road's texture map into the terrain's. Because I'd like my tracks to have some form of natural blend at the edges, I assume I'll need to alpha blend the road after the terrain is drawn. Is this actually possible or will I need to use some form of stencil? Can I use an alpha blend with ADD for this?

The options you have depends a little bit on your rendering technique. I.e. in a deferred engine you could project the road onto the terrain.

That bit is kind of already done. I'm projecting the road, in a fashion, by creating the road mesh and then splicing it up using the terrain triangles/heights so it's its own mesh and entity. It looks identical to how roads are created in Crysis 3. When you move the road around and adjust the control points, the mesh rebuilds itself to match the new contours.

I guess I'll just try the alpha blend and see how it looks.