About ISSproM: Yes, it was the multilevel-symbol I thought about.

The bridges were definitely difficult to represent. I made them very much wider on the map than in real life, but still didn’t have space for more than one or two underpass dots, which just looked confusing instead of helpful. Instead I decided to skip underpass dots on the thin bridges (as could be seen in the bulletin), but use it at this specific bridge to clarify that there are in fact three levels (only two on top of each other). As this bridge was very special and not too easy to understand from the map either way I drew it, I decided for this solution together with my map controller and clarified it with map excerpt and pictures in the bulletin.

By the way, I am not sure that the new ISSprOM will be only helpful in these cases as the outline of a bridge will be 0,4 mm, as thick as an impassable wall or an impassable fence, which easily gives you the illusion that you should not pass it. However, I think the new multilevel symbol will help for sure.