Complex Intersection Road Runtime

I’m working on a game project like cities skyline, I’ve been developing a spline road system for 2 weeks and it’s successful, to create street curves in runtime. but the current problem is how to model complex intersections like in the city skyline game.

I think that they didn’t use a static mesh model to make it because static mesh is not flexible enough to model the path. Is there a solution from experts?

My project progress:

Example cities skyline intersection: