How can I get this type of terrain texture?

34596-road.jpg

I have tried alot of shader to achieve this but without any success and vertex painting has to less details.

This looks like a model. Or perhaps a single hand-crafted texture file with tessellation. The answer is, using Unity’s terrains, you can’t get this extreme level of fidelity in a practical, scalable way. Unless you need a teeny, tiny patch of ground as depicted - even then it won’t look that good.