This is a paid asset, but now you can download EasyRoads3D Demo Project Free.
Detail this asset from Unity Asset Store: Original Link
EasyRoads3D Demo Project v1.7 (Latest version)
“If possible, please buy the package to support the developer”
Important: This demo project package is complimentary to the EasyRoads3D Pro package. Get EasyRoads3D Pro first and this demo package with additional side objects and road type examples will be a FREE download
The demo scene includes various highlighted areas with links to tutorials on our website demonstrating how EasyRoads3D can be used. These tutorials cover the more advanced features of the EasyRoads3D package.
Note that this scene is intended for learning purposes to get familiar with the tool. The scene is not optimized and does include various more complex objects targeting high-end machines. This package will be updated regularly with more content and tutorials. It is recommended to import it in a new project.