Download Easy Traffic FREE Unity. 

Create several traffic systems in your game using the “Easy Traffic” plugin. All you need to do is to create your paths inside your level, and watch the cars as they follow the paths! This amazing plugin allows users to change the attributes of the car, add semaphores, edit paths and much more!

Easy traffic has complete traffic A.I. Cars respect each other avoiding collisions and stopping at semaphores. They also recognize terrain slopes in real-time changes in the mesh.