I'm not positive I've understood what these bitches are exactly, but snow in cities poses many risks. First off, if the sun shines during the day and drips onto a smaller mound below eaves and freezes it can be dangerously slippery. I thinking wrists and coccyx. If only a slight slope is created then it can give you the impression that it's safe to step on (especially if fresh snow covers ice) whereas in reality it is like being on roller skates - that give sideways too.
Another obvious danger is that walking where you find mounds can indicate that snow and ice have fallen there from a greater height. In Alpine areas one generally leans long wooden sticks (snow level posts) against the walls of buildings to warn pedestrians or even cordon off areas. People are injured and even killed every year from falling ice. Course, it's better than being hit by something like this:
n-tv.de/673662.html
