What are your "texture detail" and "shader quality" settings. I have mine set to High for texture detail and Ultra for shader quality and don't have a problem with those assets
A bit difficult at the moment, I just had my monitor die this morning and I'm working off a small tablet right now. I have all of the parts retextured, with the correct terrain heights to make it easy to put back together when necessary. Have a try yourself, by merging a couple of pieces...
I had the same thing happen on my install of your Uintah route, so its more likely to be a corruption of the DEM rather than a local corruption of textures
Try using this as a guide for merging Kywong. from memory it only needs the track moved marginally and joined and some smoothing of terrain to get the heights the same. (this is the Kywong branch east end, trimmed)
What north side?
You will need to trim some boards off the routes to be merged, to suit the stubs on the Main South route and some realignment of tracks will be needed. The merging window always has the routes positioned where north is at the top of the window. Make sure you are merging the route in the correct...