Overall my trails shader its a whole changed to add soulercoaster features, rotations so it can be used on other meshes with different UVs and so. But the base idea is the same, the erosion base.
I dont know if its way upper because the shannon post is quite large, but i think ive started looking on to that kind of trails since this post:
That shader is from Amplify editor, but it can be easily made on Unreal/ShaderGraph/ShaderForge/RawText…
Then, the next most important thing for me, its to play around with the trail texture and the erosion texture.
(If my mind doesnt betray me, on the last trail gif, the first, third and fourth trails, had the same trail texture, simply played with another erosion texture and a bit with the values to get other results)