If you've ever ridden in a New York City subway car—or pretty much any city's mass transit rail cars—you have probably seen the emergency brake. It's hard to miss, what with its bright red handle and big placard that reads "Emergency Brake." But if you've ever read the emergency instructions that are also posted to the wall, you'll notice repeated caveats for every scenario: "Do Not Pull The Emergency Cord."
So When Should You Pull the Emergency Cord?
According to the MTA's website, "Use the emergency brake cord only when the motion of the subway presents an imminent danger to life and limb." The New York Times, which looked into the matter, relayed transit officials' instructions, who said the only reason you should ever pull the brake is in the event someone gets caught in the door or between train cars and "is about to be dragged to an unenviable fate." Unenviable, indeed.
Pulling the cord during a fire or during a physical attack by one of your fellow straphangers will only hinder emergency workers from getting to your car, which is now stuck underground.
But What Actually Happens When You Pull That Cord?
The emergency brake cord is no joke. It's not like a bus cord that politely dings and tells the conductor, "Stop, please." MTA officials described the process to the Times:
The emergency cord activates compressed-air brakes; an onboard conductor must then notify train traffic controllers, who can contact the Police Department. The braking system must be reset by the train’s crew before the car can start moving again, a process that usually takes 5 to 15 minutes and can delay tens of thousands of passengers traveling on a particular route.
Those compressed-air brakes are pretty powerful, as this video of the MTA testing them will attest:
So yeah, unless someone will be hurt by the motion of the train and that alone, don't pull that cord. A sizable amount of compressed air will hiss out onto the brakes and you won't be going anywhere for a while.