Well, if any of the segments break, then draw the segments that survived instead of drawing the simpler solid beam. That would also make broken links very easy to spot, just look for where your bridge stops looking pretty.

But since we're on the subject, I'm sort of confused as to why the bridges are constructed the way they are anyway. In BB, the links that you drew were the links of the bridge. In Pontifex, it replaces each of your links with beams made up of tons of individual links. This can actually have problematic effects, since when you want to build an arch, the square segments tend to mess up your slope and make the bridge more prone to breaking. Why not fix that problem while saving a ton on physics calcs as well by just using solid beams? I don't think anyone's PC would be a problem then.