Hi @daniel_martinF8PPE, alignments and layout profiles are set to build the corridor once you create the intersection. So, you can look for them and make the adjustments required to get the elevations on the mentioned road to align as accurately as needed. Furthermore, main roads' layout profiles might be adjusted when the intersection is created to accomplish modest conditions for the intersection. Therefore, if the changes that C3D makes automatically are not precise, we can always adjust what we need to increase precision.
I hope this helps. Best regards!
Camilo Fernández
Civil engineer | Specialist in design, construction, and maintenance of roadways