I've been playing around with bridges to see how they fare when it's not just a gap of water our puddings must cross.



Of course, something with this much potential to be awesome can't possibly work out well under EA, although I had suspicions for what comes next as soon as I came up with the initial idea.



Sims and Cars drive OVER bridges just fine, but like the in-game camera, there is no concept of going UNDER or THROUGH something.



It doesn't seem to impede travel to a Sim's destination in anyway, but unless you're fine with flying cars and floating pudding, bridges must remain as routes over the impassible only. I don't expect that messing with passability or routing data will change this because the means to do so seems very limited, but regardless I doubt it's in the game's capacity to allow for different altitude layered pathways.