These things look like drum shells without the heads. But they're pipe things. I'm not sure what exactly they're called, but I know that they go around pipes, maybe they somehow help to fit them together:
This was on Lafayette last week. I'm sure the street is still torn up (at the rate the city gets things done). I have a wider shot of the damage, and it may yet see the light of day on the site. But for now, you get this more close up affair taken mit der Rolleiflex.
I haven't been playing the piano enough lately. I'm going to remedy that immediately.