So I will try to make you guess how to do it. I do not think that C3D Roundabout will help you to do this type of roundabout you have to do it manually, with separate alignments to get what you want appropriate assemblies of course and after you will model it if you are skilled in code set styles and others you can assign materials in civil 3d for assembly links after you have to go in infraworks(very important is that Infraworks and C3D must have Same release data 2020 or 2021 whatever) so you can import directly C3d Corridor in Infraworks from Data Sources panel. and walla!
you get a nice Infraworks model if you modify the C3D corridor it will change automatically in infraworks after the refresh the data source.
Here is an option of importing C3D model

Beka Tchigladze
Road/Highway Technical Designer
AEC Collection/C3D 2025
WIN 11 64 PRO
Predator Helios 18, Intel Core i9 14900HX, 32 GB
NVIDIA RTX 4080, 12 GB
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