I have dealt with oh so many times where it is impossible to build a bridge to a certain area on matter where i try all error out with 'unsuitable grade for construction' 'cannot place network on this terrain type' or it just says 'to build a bridge drag the bridge to land" (can remember the exact message)(but what i call that problem is that it isn't recognizing that the land is there because it is still telling me to keep dragging to build a bridge) which makes island and other land not possible to get to because every land to land will result in one of these problems causing a lot of my city to have lost of land inaccessible. is there any mod that will correct this or that will allow me to create bridges on more terrain than without... any mod that will allow me to get to those inaccessible areas with a bridge or whatever would highly be appreciated!!
The same thing happens for me too. Start dragging the road or rail or whatever about 10 tiles away from the water. It then forms a smooth slope, so this must be caused by a slope mod.
The trick is to start dragging from the right distance. :)