By Justin Doughty
A small quirk that may be noticeable when using the UKIE template in Civil 3D 2019, is the display of surfaces in certain visual styles. This can be seen either in the main model window or the object viewer in a variety of visual styles like shaded or conceptual.
It looks like another surface overlapping the selected surface, almost like a volume surface, but with a solid colour:
The easy way to stop this is to edit the style of the surface and turn off the visibility of the Border:
This seems to be the border colour bleeding into, or filling the surface itself, and turning it off stops this from showing. This has already been logged with the developers at Autodesk as a change request.