An engineer says that he's solved one of New York's most eternal questions: How long should you wait for a subway train before giving up and finding some other form of transit?
To cut a long story short, it's 11 minutes.
In his post titled "NYC subway math," Erik Bernhardsson analyzed date from the MTA and found that after 11 minutes the odds of there being major delays on the line begin to rise. After 15 minutes, the additional waiting time is another 8 minutes. After 23 minutes, the additional waiting time is another 12 minutes. Basically, the longer you wait, the higher the chance of their being a significant delay.
So next time you're in a hurry and a quarter-hour's passed with no train, might want to think about jumping on Citi Bike.