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I assume you are asking the deepest structure of any sort that exists. Here is an infographic :
Source : https://alansfactoryoutlet.com/the-deepest-underground-structures-in-the-world/
One mystery undersea structure:
Cuban Underwater City
The Cuban Underwater City is another underwater structure that raises more questions than it answers. What appears to be ...
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If your volunteer is a very small person, maximum shoulder width of 23 cm/9 inches, then the answer is 12,262 metres (40,230 feet) deep in the Kola superdeep borehole in Russia.
I can't find the "height above sealevel of the start" to subtract from total depth of borehole, sorry. Best I can find is 230 metres above sea level.
They probably won'...
13
The Kidd Mine in Ontario, Canada: per the Wikipedia article, it is "the deepest accessible non-marine point on Earth" at "2,733 metres (8,967 ft) below sea level". I found this from the Wikipedia article on Extremes on Earth, which differentiates between depth from the surface and depth below sea level, and also between an actual mine vs. ...
4
The point you are looking for is very likely located in a mine. You could check the list of deepest mines by depth below ground, and then find and subtract the surface elevation for each.
(This still assumes humans can go to the deepest points of these mines, which may or may not be correct.)
1
As you mentioned bitumen, tire rubber particles, fine dust, and oil can cause a roud to be slippery after a dry spell.
But in your case it's not that. it could be a caravan of old trucks crossing the road earlier, have left a perfect mix of oil and rubber, or their load could have been constraction silty/gypsum material which has blown over the road due to ...
1
Usually roads become slippery after a first rainfall of the season because of all the dust and oil particles that have not been washed away and they are mixed with the moisture. Basically they create a slightly more sticky film (compared to rainwater) that acts as a lubricant between the road and the tire.
(Any rain Harvesting system uses a First flush ...
1
When a car moves in a circular trajectory a centrifugal force is ""compelling" the car to maintain its straight line. In order for the car to move in the circular trajectory a centripetal force is required.
Sine the motion is radially outward, (and the friction is opposite to the direction of the motion) the friction that develops is inwards.
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