This is a paid asset, but now you can download ProRoad Free.
Detail this asset from Unity Store: Original Link
ProRoad v1.2.174 (Latest version)
ProRoad is a road creation tool for Unity. The basic concepts together with many rich features makes it not only easy to use but a solution for any games where roads are important.
ProRoad and it’s tool set has been used for making our successful racing game Revhead. We decided to release these tools for the public to help get over those obstacles, which comes when you are making a simulation game.
ProRoad comes with features like radius based curves, road banking, intersections, segment-based material/texture usage, road bumps, terrain tree/detail clearance or automatic (value based) indentation. The generated road mesh is exactly on the terrain surface with the same tesselation without any offset, however you can set Mesh Y Offset to raise the road mesh in the desired height if you need it. Special shader is provided to avoid Z-fight issues, also, HDRP and URP shaders are included to support Universal/HD render pipeline. There is a Decal mesh generator in the package to make road paintings, oil stains and other cool visual content, a Surface map detection tool to allow to set different road surface types such as tarmac, gravel, dirt and more.
ProRoad also comes with additional tools, such as ObjectPlanter tool, Logger module, Surface map tool, Decal mesh generator to help adding objects or integrate it with your scene in your own game.
ProRoad is compatible with Vegetation Studio.