Spline Mesh Mud Road using dither alpha transparency

Hey all
I was watching a Live Session video from CG Society ( https://www.youtube.com/watch?v=oRfVFh_6OyA ) and the person who was showing off their work (Clinton Crumpler) mentioned that he made his mud roads using spline meshes and the material used dither alpha transparency. I’m still trying to get my head around the material editor as I only normally work in blueprint scripting and not materials, etc. Is there anyway someone here can help break down just how Clinton was actually able to achieve this kind of affect using a material? I’m kinda stuck on how I would go around creating something like this myself. I don’t know if he had a normal material which had the tracks on it which then had an alpha or if he had just a specific alpha for the tracks, etc. Any help is appreciated. Thanks.