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grambell789 t1_je55ot0 wrote


Gfoley4 t1_je5rouo wrote

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.


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.


alheim t1_je5rxaw wrote

Generally, the primary manhole has a sort of metal ring/extension on it. The extension is about the thickness of the new course of fresh assault. It can be removed temporarily to lower the height of the manhole after the street has been cut