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Comment by ice109 | Hacker News Reader

there is no way that the NYC Subway's AC's dumping heat into the tunnels contributes in any meaningful way to the temperature inside the stations - the tunnel system is enormous relative to the trains. much more it's simply NYC summers are sweltering and the stations aren't well ventilated at all.

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Did you read the linked article? The heat of the London Underground tube tunnels is directly caused by heat released by trains (though primarily from brakes and friction, not AC), and has nothing to do with season. It's swelteringly hot down there in winter.

I don't see why it'd be any different for NYC, where I live.

Many NYC subway tunnels are not 'tubes' and are shallow enough to have surface access. So part of the answer is probably that the NYC subway is a more open system.

The same is true of London (also mentioned in the linked article). The linked article is explicitly only talking about the deep tunnels, which NYC also has.

The point is there are more shallow, cut-and-cover tunnels in NYC than in London. London has entire high-traffic lines that are deep tunnels.

Yeah, NYC is a very different system. The deep tunnels are very well ventilated. Go to a station at the end of a deep section, like High Street and you can feel the wind blowing out because of the forced-air ventilation system. You can also see daylight from the subway trains throughout the system, because it's that close to street level and there are ventilation grates every hundred-ish feet.

Actually it is related to the air conditioning. Prior to AC, the subway and its platforms were cooler than the outside. Still not pleasant on a 100 degree day, but certainly not as it is today: the platform will be significantly hotter than outside. Just gotta survive long enough to board the train.

https://cityroom.blogs.nytimes.com/2008/08/08/complaints-abo...

For London the passengers contribute 2% of the heat. In a more efficient system they would contribute a larger percentage.

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