In previous versions of InRoads it gave the option for when creating the surface to exclude from triangulation, as I can tell in OpenRoads Designer when generating the surface I do not see the exclude from triangulation. How can I do this with OpenRoads Designer?
OpenRoads Designer terrains are created differently from the InRoads DTM. In creating a terrain, if there is a feature or features that you do not want triangulated, do not add those features to your terrain. A 3D feature can still be displayed in your design file, or cross sections even, without adding it to a terrain itself.