There are issues with InfraWorks 360 where roads cross each other at different levels. It shows angle point vs a nice smooth vertical curve or "lump" produced in one road by the second road (underpass) underneath it. 
Environment:
InfraWorks 360 2018.2 and older
Causes:
This is the design default with Bridges.
Solution:
At the moment, the minimum clearance needs to be as follow:
Above 2.5 meters for component road
Above 5.0 meters for sketch road
Note: If the clearance is less than 2.5 meters, a junction will be created instead. The new geometric modeling framework will be enhanced in the future.