need any type of bridge mod to fix this problem

[ReshiramLover 48]

I have an issue with maps created from actual pictures just turned grayscale so I can get some pretty odd terrain, and the issue with that is there is a lot of places that are impossible to get to because all ways to get there error out as "unsuitable grade" is there any type a bridge mod that can fix this issue??? even when it makes sense that it would allow the bridge to be built, it doesn't allow a lot of the times... does anybody know of any kind download to fix this???