This fascinating piece from The Atlantic explains how many of the NYC subway lines work and why there are not countdown clocks for them.

There are people who stand every morning outside the Carroll Street station in Brooklyn staring dead-eyed into the middle distance. They stand still in ones and twos, clearly strangers to one another, mostly quiet, as though they’d stopped on their way to work to take note of some spectacular disaster in the sky. But you look in the general direction they’re all looking and there’s nothing there.

They are, as it turns out, waiting for the F train. Carroll Street is one of the rare New York subway stations whose trains are boarded underground but where you can stand outside to see them coming. When you spot the F rolling down the bridge, you have just enough time to run inside to catch it. So people stand there waiting. They wait for as long as it takes, for as long as their patience will allow, because in 2015 there is no app, no screen, not even a scratchy voice over a PA system that can tell them when the train is actually going to arrive.

But here’s the truly crazy thing: The only people who know exactly where that train is are on the train itself. The signal-tower operators don’t know; there’s no one in the Rail Control Center who could tell you, because the F isn’t hooked up to the Rail Control Center. Today, for the F train—along with the G, the A, B, C, D, E, J, M, N, Q, R, and Z—the best the system can say is that the train will get there when it gets there.

This is both infuriating to riders who want to be able to plan their commutes—spend those extra ten minutes at home, or forego the subway altogether if there’s a long delay—and a symbol of a broader failure. It’s hard to say what, exactly, but something important seems to have gone wrong when the tracking apparatus for subway cars is worse than it is for pizzas.

The best estimates today are that countdown clocks that tell you when the next train is coming will arrive on the so-called B division of the New York subway system in 2020. (The A division already has them.) That would make them about nine years overdue. It is easy to take for granted that governments move slowly, particularly on large infrastructure projects, particularly when those projects involve software. But we live in a world with cars that can drive themselves. Trains are huge objects that move in one dimension. How could it cost hundreds of millions of dollars and take nearly a decade just to figure out where they are and report that information to the public? Really: How?

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