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Gfoley4 t1_je5rouo wrote

Reply to comment by grambell789 in In Washington heights they tour up the roads to do work and revealed the old cobblestone beneath (184 & Pinehurst) by soylentgreenis

You can see in the picture they built a temporary asphalt ramp around the manhole in the center. I’m not sure the SOP for NYC in particular, but most structures have adjusting rings sitting just below the frame/lid that you see. A crew will adjust the structures in the road to the final grade before the paver comes by. This is usually a concrete patch around the structure, either on the final grade or in a layer below so you don’t see it. That way they just pave around the structure.

Sometimes they are at the same grade now and don’t need adjustment. A company I’ve worked for also had a different specification for manholes in the middle of the road - adjusting the frame downward so it’s not sticking up of the road in the interim condition - then back up again to the final elevation.

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grambell789 t1_je5sauv wrote

I'm more curious about the milling process. I've seen the machines and it just looks like a big rotor with knives - hammers on it. how to they deactivate those when that part of the rotor gets near the manhole, is there some kind of ferrous sensor? I never see a manhole battered so they must be pretty effecicent at detecting and avoiding them.

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