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Old 07-22-2017, 04:33 PM
 
3,333 posts, read 3,280,911 times
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Quote:
Originally Posted by iammax View Post
To be fair, if there weren't engines spewing hot fumes and the body heat of millions of people packed in tight quarters heating them up, I'm sure the subway tunnels would be cooler than topside.

Too bad about those fumes and bodies, though.
Subway cars and platforms themselves generate heat as well; normal car operation (braking, on board batteries, etc.), station lights, station infrastructure, etc.

To say that underground subways are naturally cool is simply incorrect. If they are designed correctly to handle certain amounts of heat then they'll be cool. If not, they'll be hot.

Some coal/mineral mines are thousands of feet underground and they're not naturally cool. Never have been.
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Old 07-22-2017, 04:38 PM
 
Location: SC
8,382 posts, read 5,021,700 times
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Quote:
Originally Posted by iammax View Post
To be fair, if there weren't engines spewing hot fumes and the body heat of millions of people packed in tight quarters heating them up, I'm sure the subway tunnels would be cooler than topside.

Too bad about those fumes and bodies, though.
Not really fumes. But a large electric motor can put out a lot of heat and smell of the motor (yes, they have a smell of ozone) combined with the lubricating grease on the trucks, it can be distinctive. The 'tight' bodies could also be a small factor. A packed train car can carry a lot of stink.
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Old 07-22-2017, 04:38 PM
 
18,236 posts, read 11,645,412 times
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If we can inject a bit of sanity and civility back into this debate.


First and foremost laws of physics (natural convection) means that yes, to an extent there is a pattern of air flow from underground subway stations/tunnels to street above. You only have to stand at the top of any subway station (well maybe not the new SAS ones) especially when a train in entering or leaving station to feel the breeze.


It is no different than dampers on a fireplace/boiler/furnace or anything else that gives off/produces heat. Also is the one of the reasons why those grates were built along street in first place.


Marilyn Monroe's dress got some help (fans), but ask any female past or present wearing skirts what happens when a train goes by:





That being said natural convection will only get air movement but so far. Especially as heat builds over several successive days of hot weather. Added to this the heat and moisture given off by humans, and the trains themselves. The latter has increased now that nearly all subway trains have AC. All that heat coming from condensers has to go somewhere.


Cannot speak to how much human activity (including the trains themselves) increase subway temps; but there is evidence to be found. Just speak with anyone who has been to the abandoned and sealed off areas.
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Old 07-22-2017, 04:48 PM
 
18,236 posts, read 11,645,412 times
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Quote:
Originally Posted by BugsyPal View Post
Just as with all deep tunnels (think Holland, Lincoln, Battery, Hudson River, etc...) the SAS "new" stations on UES have a powerful ventilation system. There is also an air conditioning system which IIRC was only recently activated.


Brand-New Second Avenue Subway Stations Swelter, Despite MTA Promise of Climate Control | NBC New York


If you notice unlike other subway lines (IRC, BMT, etc...) in Manhattan the SAS new stations do not have ventilation grates along sidewalks. Air is brought down and circulated via vans. That plus the depth accounts for some of the coolness (think tombs, graves, and other things below ground), but only works to a point.


Remember trains themselves create heat (more so now that all have AC systems), and then you have people/passengers. Without some sort of ventilation (forced or natural) air down there would be stagnant and laden with fumes.
"Air is brought down and circulated via vans."


Make that "fans", sorry for the typo.


Carry on.....
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Old 07-22-2017, 04:56 PM
 
3,333 posts, read 3,280,911 times
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Quote:
Originally Posted by BugsyPal View Post
If we can inject a bit of sanity and civility back into this debate.


First and foremost laws of physics (natural convection) means that yes, to an extent there is a pattern of air flow from underground subway stations/tunnels to street above. You only have to stand at the top of any subway station (well maybe not the new SAS ones) especially when a train in entering or leaving station to feel the breeze.


It is no different than dampers on a fireplace/boiler/furnace or anything else that gives off/produces heat. Also is the one of the reasons why those grates were built along street in first place.


Marilyn Monroe's dress got some help (fans), but ask any female past or present wearing skirts what happens when a train goes by:





That being said natural convection will only get air movement but so far. Especially as heat builds over several successive days of hot weather. Added to this the heat and moisture given off by humans, and the trains themselves. The latter has increased now that nearly all subway trains have AC. All that heat coming from condensers has to go somewhere.


Cannot speak to how much human activity (including the trains themselves) increase subway temps; but there is evidence to be found. Just speak with anyone who has been to the abandoned and sealed off areas.
Simply put, most NYC underground stations were not engineered with sufficient ventilation to accommodate modern AC exhaust spewing train cars.

I'm sure plenty of people have stood by a condenser unit. Even a relatively small 4 ton unit, expels a massive amount of heat. A 4 ton unit can remove 48,000 BTU's of heat in an hour aka the amount of heat generated by 48,000 match sticks.

Each R160 train has a 7.5 Ton AC unit. Do the math of how much heat that is per car, per station along a particular route.
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Old 07-22-2017, 05:02 PM
 
18,236 posts, read 11,645,412 times
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Quote:
Originally Posted by wawaweewa View Post
Subway cars and platforms themselves generate heat as well; normal car operation (braking, on board batteries, etc.), station lights, station infrastructure, etc.

To say that underground subways are naturally cool is simply incorrect. If they are designed correctly to handle certain amounts of heat then they'll be cool. If not, they'll be hot.

Some coal/mineral mines are thousands of feet underground and they're not naturally cool. Never have been.

With all due respect sir, no you are not correct.


It varies by several factors but underground temperatures will nearly always be cooler than surface.


https://www.physicsforums.com/thread...ground.826193/


Ground Temperatures as a Function of Location, Season, and Depth




https://pubs.usgs.gov/bul/0701/report.pdf


What poster stated is quite correct, anything underground (again factoring in variables) will be cooler than at surface. What you describe is human activity which of course will raise temperatures.


Those mines or whatever located "thousands of feet" underground will be "warm" if they are located in relation to sources of geothermal heat. All those hot springs and geysers obviously start underground but are high to near boiling water temps.
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Old 07-22-2017, 05:08 PM
 
3,333 posts, read 3,280,911 times
Reputation: 2834
Quote:
Originally Posted by BugsyPal View Post
With all due respect sir, no you are not correct.


It varies by several factors but underground temperatures will nearly always be cooler than surface.


https://www.physicsforums.com/thread...ground.826193/


Ground Temperatures as a Function of Location, Season, and Depth




https://pubs.usgs.gov/bul/0701/report.pdf


What poster stated is quite correct, anything underground (again factoring in variables) will be cooler than at surface. What you describe is human activity which of course will raise temperatures.


Those mines or whatever located "thousands of feet" underground will be "warm" if they are located in relation to sources of geothermal heat. All those hot springs and geysers obviously start underground but are high to near boiling water temps.
Of course underground temps are cooler than surface temps with all else being equal. However, that's not what we're talking about here.

We're talking about underground NYC subway stations. What do underground caves have to do with NYC underground platforms apart from that they're both underground?

It's like saying, no matter how much **** you stuff in a refrigerator, it will always be cool because it's a refrigerator. That's simply not true. Past a certain point of content load, addition of new contents, opening the doors, etc. all refrigerators will struggle to keep up cooling.
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Old 07-22-2017, 07:34 PM
 
Location: Brooklyn New York
15,226 posts, read 23,743,496 times
Reputation: 19847
has anoyone ever been down the 59th / lexington R, N...456.....(Im sure all of you)
its like walking into the inner depts of hell.

this past thursday, waiting for a N train at 59th / lex the air, still, extremelly hot...
then as you look into the tunnel and see the train way in the distance, I mean way in the distance, suddenly the wind that starts blowing thru is un believeable, hot, but wind, never the less......then the train comes and its an R***sigh....it passes and the station becomes hot all over again....

then the wind kicks up again as i look into the tunnel i see the train way in the distance....finally, its my N.............

moral of story, these tunnels are so deep, and not cool at all.

again, its like walking into the inner depts of hell..................

Last edited by nightcrawler; 07-22-2017 at 08:03 PM..
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Old 07-23-2017, 07:11 AM
 
Location: Manhattan
20,129 posts, read 26,407,309 times
Reputation: 9021
Quote:
Originally Posted by pierrepont7731 View Post
Heard on the news that yes, new stations had HVAC system that was to be turned on soon. Likely explains the cooling.

Correct,
I asked an MTA worker yesterday and he said that the air conditioning in 4 the stations (SAS) had been turned on just this week. I am guessing on Friday, July 21.


Thank you, God.
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Old 07-23-2017, 07:17 AM
 
18,236 posts, read 11,645,412 times
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Quote:
Originally Posted by Kefir King View Post
Correct,
I asked an MTA worker yesterday and he said that the air conditioning in 4 the stations (SAS) had been turned on just this week. I am guessing on Friday, July 21.


Thank you, God.


As link one posted upthread stated it wasn't on "yet" as MTA was waiting for DOH approval.


Took the SAS about two weeks ago down to Union Square from 86th, and while it wasn't hot as "above ground", it was still cooler than say the 77th/Lexington station.
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