The Answer:

We've wondered about this ourselves. The safety information we've found regarding trains invariably stresses cases in which the emergency cord should not be pulled by passengers. If there's a disturbance on the train, or if somebody's sick or injured, the cord should not be pulled, they say; it will actually make it harder to get medical attention or security intervention in a timely manner. Which is all well and good, but then why have the cord at all?

We've finally found a plausible rationale. According to the Metropolitan Transit Authority in New York City, "Use the emergency cord only to prevent an accident or injury. For example, if someone gets caught between closing subway car doors and is being dragged, pull the cord." This makes sense; such a situation would require immediate action, the train would probably be just starting to accelerate, and people right there would be more likely to notice than the conductor.

What we don't know at this point is how often—if ever—emergency cords are actually used in such cases. (If any of our readers has an answer, please feel free to get in touch.)

—The Editors