US National Bridge Inventory

at https://geodata.bts.gov/datasets/national-bridge-inventory/about
(and older versions of this set)

Every bridge has "year build" data (just needs to be interpreted properly/plausibly)

They were probably mountaintop removal quarries in the past, but I am pretty sure that they are now landfill/dumping ground for rock/dirt/excavated material.
(On Bing) It looks like they are piling up material everywhere or did at some point, but not like they are still digging for material. On the south/southwest on these areas are two very large dams. The material is likely from underground mines in the area.
Compare e.g. with an active quarry osm.org/edit?#map=13/37.77786/-81.61654
I think there is a noticeable difference

Maybe there are also better tags such as was:quarry+natural=scree/scrub or something, i don't think it is a quarry. But no strong feelings either way.

Looks good, especially the street lamps!

Thanks, there isnt like "the" source, there are a lot of different sources I use occasionally for different things.
Underground lines -the ones I see & map- are usually visible by combinations of scars from construction activity, small switching boxes visible besides roads, line transition poles, older aerial images where the line was still overground etc.
The voltages are usually from company documents/system operator/system planning documents on the web, FERC elibrary, EIA generator interconnection data, public utility commission documents, etc

relation/18673593

This was 4 years ago, one of my first edits, I have no idea what exactly happened there.

I re-added the lake, is there anything else missing?

I replied at the thread

Do you mean the "voltage=115000;13860" tags on substations? They are from FERC Form 1 annual reports -elibrary.ferc.gov-, which include listings of operated substations+associated data, such as primary and secondary voltage, see https://data.catalyst.coop/ferc1_xbrl/substations_426_instant/158598 https://data.catalyst.coop/ferc1_xbrl/substations_426_instant/1903 https://data.catalyst.coop/ferc1_xbrl/substations_426_instant/1779
three substations which I added here with 13.86kV as the listed "secondary voltage".

Disclaimer I have no electrical background.

Hello, I am not quite sure where I got the name from, but I assume it is named like the city and I made a typo there. I changed it to "Cincinnati".

(Just for clarity, the changeset comment refers to the "Mid-Valley Pipeline", which I mapped along with various other details along the way (relation/16195373))

Hello, those are from the US Federal Railroad Administration's "Safety Map" at https://fragis.fra.dot.gov/gisfrasafety/

(Those codes are also posted at every crossing on a little blue sign under the crossbuck, verify using StreetView; also there are many crossings where I tagged this code into name=*/ref=*, these should be moved to "ref:fra_crossing=*")

Where exactly have you discussed this mass edit?

Hello, you changed substation=transmission to =distribution on various substations.
Many of these substations are 230/69kV, and 69KV is transmission system.
substation=distribution is for substations feeding the distribution grid, which is not the case with substations like way/171484619

See also substation=distribution?uselang=en

fixing my own tagging to something more accurate

no idea how that happened, but thanks for fixing!

thanks for your info, I throught because they were rebuilt to be almost fully grade seperated, motorway would be fine, but good to know.

If you use these circles to create more accurate mapping, there is no issue with doing that, just make sure you don't tag those circles with tags that imply things that aren't there like "man_made=pipeline", use tags like "note=temporary mapping help" or similar, and remove them when you finished mapping the alignment.