NYC Subway Riders See 'Exceptionally High' Air Pollution

10 points by arbuge 10 months ago | 7 comments
  • amluto 10 months ago
    I wonder what the source really is. NYC trains seem to already be equipped with regenerative brakes and resistor brakes:

    https://www.nyserda.ny.gov/-/media/Project/Nyserda/Files/Pub...

    And those don’t rub. There will surely be some emissions from the wheels rolling imperfectly on the track, but, perhaps naively, that should be small. I wonder whether NYC trains also have friction brakes that they use for the last bit of stopping. If so, perhaps improved control algorithms or improved motor drivers could avoid using them until the train is fully stopped.

    There’s also another possible effect: trains produce high air velocities, and they could stir up small particles that have settled in the ground. A serious effort to clean up the tracks and stations could reduce these particles.

    • arbuge 10 months ago
      From the article:

      The researchers found that the rubbing of metal wheels and brakes on the rails releases metal particles, which appear in particular concentrations as the trains arrive at a station.

      “We noticed that when a train arrives at the station, the concentration in the air shoots up, and about 15-20 seconds after it leaves, the concentration slowly comes down,” said Ghandehari. “This implies that it is the stuff that’s at the bottom of the tunnel that gets churned up and deteriorates the air.”

      • amluto 10 months ago
        Right, so they covered lots of bases. But they didn’t actually discuss how much of the pollution came from each source, and they didn’t address why the brakes are being applied.

        Most modern EVs can come to a near stop using regenerative braking without applying mechanical brakes at all. Some motor controller software could surely bring it to a complete stop with minimal or no hardware changes. (If you find a safe place with no obstacles, you can generally stop a car, EV or otherwise, by driving slowly forward, shifting to reverse, and stepping gently on the accelerator. In a car with a conventional engine, this involve friction internal to the clutch or torque converter. In an EV, it’s the motor applying torque opposite to its direction of rotation.)

        A subway train quite similar to an EV.

    • jmclnx 10 months ago
      Not a big surprise, when I have used the subways in NYC, the air always has an odd smell. If I can sense it, the smell must be real bad. I have a very prro sense of smell.
      • reverius42 10 months ago
        Yeah, there is definitely a unique smell to NYC subways. I've never smelled it anywhere else but I can almost taste it in my mind years later. Never thought about it until now... hope it's not too cancer-causing.
      • antisthenes 10 months ago
        Worth keeping that N95 mask on, I suppose.
        • stemlord 10 months ago
          Hope this encourages some miniscule semblance of climate control in some of these sweltering stations
          • 10 months ago