First off I think bridges are a wonderful addition to the game. I have made use of many that make getting from point A to point B much quicker and it is nice that the Devs decided to lower decay rates and base it on usage, however, I have run into a couple of serious issues with off deed bridges.
Although not all builders do this, some make use of buildings for the support structure between the arches of multi-span bridges or as the foundation for the start/end of a bridge. I have in my travels I have come across bridges designed this way that have suffered decay on the floor/ceiling of the buildings that are incorporated into the bridge structure. This essentially renders the bridge useless once it decays completely. Unlike the rest of the bridge, buildings can't be repaired by just anybody.
I'm not trying to suggest how bridges should be built, these are just my observations as I travel throughout Wurm.
Skyefox
Mayor: Albia Estates