We've all fallen asleep on the train and missed our stop. It's a pain, because that means going to the other side of the track and having to get on the train yet again. Or, if it's late at night, it means being stuck in a strange and possibly frightening place.
You begin by picking your line, selecting your starting station, and picking an end point. A few seconds before your stop, the phone will vibrate and wake you up. Here's the trick: the app senses when the train is moving or not, so it can tell how many stops you've gone.
Domhan, who used to work at Bitly, came up with the app after his girlfriend took the subway, fell asleep, and "ended up where she didn't plan to go." It's based around a smartphone's accelerometer, which can tell if trains are moving or not the same way it can distinguish between someone doing serious exercise and, say, walking around the house.
See a video about the nap app here:
MetroNap is one of dozens of entries in the New York MTA's App Quest. Others include an augmented reality app that helps people read signs better (see video below) and Exit NYC, which helps riders find their exit more easily. (Transportation Nation has more here).
The contest, which is sponsored by AT&T, has a grand prize of $20,000. You can vote for your favorite entry until September 10.