Well, may as well give this a go. In beta 2 i did a city in Norwich Hills, where there is a single rise up to the overlooking plateau. I had a heck of a time getting an avenue up that slope without graphical bugs showing the terrain spilling from under the roadway on the wider zoom. When I looked in close, the spilled terrain disappeared. I was amused, because it looked like pictures of Seaside Heights after hurricane Sandy.
I wish I had taken screenshots of this, but I eventually found a sweet spot after repeatedly repaving the avenue to avoid the sides of the hill. So, sure, there's a workaround, but this was certainly annoying. Even some basic tools would fix this, but that's not going to happen, we know that. At the core though, I think there's something with the zoom and how terrain is rendered causing the graphical glitch. Has anyone seen this? I've seen no mention of it here or on the official forums. I had this happen to a lesser degree in Clearwater, near the shoreline, but Norwich Hills has much more drastic height levels that make this a repeatable, testable bug, at least on my machine. I do have an older graphics card, an 8800 GTS, but that's well within the required specs.