Bridges

[torangan]

If a bridge design only works for 1 hex bridges then it's simply the job of the map designer not to use it otherwise. Additionally a random map generator should follow this constraint or simply not use this terrain type at all. Nothing too fancy, just the same as having no intention to support every possible combination of terrains.
It's enough to have art for the common cases and if someone really needs a rare case then good luck getting a transition or whatever is required done.

[sparr]

For a rope bridge, if someone wanted to actually draw the art for 2 3 4 5 6 etc hex spans, then they could all work just fine.

Intersections would look unrealistic. Even if we had the art, they would be magically raised into the air, at the starting height (land level) of the surrounding spans.

[joshudson]

There is a currently-unused stone bridge over chasm in UtBS. Looking at the WML suggests that it is limited to straight lines but can be multihex.