This is a paid asset, but now you can download Tracks and Rails Free.
Detail this asset from Unity Store: Original Link
Tracks and Rails v4.1.0 (Latest version)
Add physics-based track to your project!
Go for a trial ride, right now.
This extension allows to you to create track in any custom shape, then attach a cart to it and actually ride the track. Make platforms that slide when things hit them, metro trains that ram into barriers, broken elevators, roller coasters, invisible flight paths, rocket-propelled trains and more!
Meshes are generated automatically. Four track templates are included. Use these or make your own. Use any model you’d like for the cart, or just place a camera on it and go for a ride!
Interactions are physics-based. The cart has a rigidbody and can be pushed, pulled, run into, jumped onto, and accelerated like any other rigidbody. The tracks themselves can be given acceleration and braking properties. Use the included scripts to give your carts sounds as they roll on their way.
Use scripts to create, link, and bend tracks at runtime. Build a train yard or blow up a bridge!
Heavy editor support. Quick track laying tool, direct control point editing, relinking tools, undo, and mass-edit support.