Accurate? Pretty much so. But then there's the Garden State Parkway effect. You know, when you're zipping along and all of a sudden, there's a bunching of traffic - a short, jarring delay - but for no apparent reason. And then, just as mysteriously, things open up again.

So it's accurate when it tells you that the lines are long or not so long. And it's pretty much accurate when you are in the terminal, looking at your smartphone, and deciding that minute which line to choose. But I wouldn't count on it to be all that accurate in advance, unless it's warning you that lines are very long.