Create a 3D overpass

[IB3]

I'm looking to design a 3D overpass without using city engine. I want to visualize two intersecting roads represented as polygons, with one road passing over the other. While experimenting with the elevation properties parameter, I noticed that adjusting it causes the entire road to elevate uniformly. However, I aim to create a more realistic representation by incorporating multiple levels, mimicking the gradual elevation change seen on real overpasses.

Could anyone provide guidance or suggestions on how to achieve this effect? 

Thank you in advance

[IB3]

I found a way by creating it from scratch, from a 2d polygon with different z-values used to extrude the 3D shape.