Hi @Anonymous ,
the planning roads don't have their own profile (=elevation) and they need a terrain to be draped on.
If yo switch off the terrain, the roads disappear as well.
Maybe there is a workaround with a round trip via Civil 3D.
Load the model into Civil 3D, you will see an existing ground surface and a road surface. Export the road surface as LandXML and import that LandXML to InfraWorks. Now the roads have a drape terrain and you can switch off the existing ground.
Regards,
Karsten.
Karsten Saenger