Help with roads

Hello all. I am working on developing a road system for a title game taking place in a city. I have made a modular road system. But it does not provide the diversity I am looking for. I want to be able to follow terrain and make random bends... etc. I also would like to attach some concrete curbs and walkways to the sides so that it will always follow the road. And intersections are a must. I understand I can use decals and such for the stripes... but what about getting a nice curved intersection. I see this in other games like watchdogs, and battlefield 4 to name a couple. Does anyone know how this can be achieved? Again... end game is cry engine.. is there a 3rd party tool involved here? Any help is greeeeatly appreciated! thanks!