I first placed the lower street and the ramp up, and came around the cliff, and this is where I had to stop:
https://www.dropbox.com/s/r97egujpl12hs ... r_Edge.png
Here I'm missin a new bridge block that allows to connect the regular road to the cliff side.
Or make this impossible (red selection box) before placing the edge blocks.
I know, I should use blocks 6-4-3 or 6-4-4 there
