ALL LESSONS & PROJECT FILES: https://www.sidefx.com/tutorials/post-apocalyptic-ruins-for-ue4/
Once the logic of the path and railway are set, you can bring it into UE4. Start by adding instances to the models for the path and the railway and making the curves editable. Rebuilding the asset in UE4 will display these curves and they can be used to place and control the path and railway.