After the recent heavy snowfall, there are teams of workmen on the roofs in the city, clearing the snow before it freezes and falls on someone’s head. They do wear safety harnesses of sorts but don’t seem to find them particularly important; I often see the harnesses sitting badly and almost falling off. If I was climbing around on an icy, slippery roof at the height of six or seven stories, I’d want to be pretty securely attached…