> Yeah, it's almost surely a case of remembering the handful of times when the clocks were inaccurate because they caused you trouble, while forgetting the hundreds of times when they worked correctly.

It absolutely is not availability bias, as demonstrated by the concrete data included in one of those links.

But even if it were - the whole point of having those signs is to alert you about the actual state of the subway, factoring in delays or service changes. Otherwise I could just download the PDF of the scheduled train times from the MTA's website and look at that. (Yes, those exist. There's almost no reason any person would ever need to look at them).

> They do work correctly most of the time, and the A division works even better than the B division, as you'd expect. (the opposite of what OP claimed.)

No, that's not the opposite of what I said. The A division is the IRT lines. Those are the ones that use the ATS system (which was outdated even at the time it was rolled out), and that's why the IRT lines (the ones with the LEDs on black background) are at least somewhat useful. Even if the train is delayed from its normal schedule, the times posted there are supposed to be somewhat accurate because it's using the ATS signal data.

For the B division (the BMT lines), you might as well be using the static PDFs that post the idealized train schedules[0]. I am not exaggerating; that's literally the data they are displaying. Once in a blue moon, for very serious delays such as a train accident, it will tell you that a train is "delayed" instead of telling you the updated ETA, but that doesn't help, because you want to know how long the train will take, rather than just the fact that it's "delayed"[1]. Most of the time, though, it won't actually update the time at all, and it'll keep displaying the wrong estimate until the train is literally about to pull into the station (at which point it'll skip straight to "0 minutes away").

The reason they don't tell you more information is because that information doesn't exist. They don't know where the trains are, beacuse the BMT lines use outdated signaling technology that's decades old, and the MTA has stonewalled all efforts to upgrade them[3].

So, in short, the BMT countdown clocks are useless because:

* They only publish the scheduled times, not the actual estimated arrival times

* Only about 50-60% of BMT trains arrive according to the times posted on those schedules

* For the remainder, it usually displays the wrong information, because it doesn't have any way of knowing that the information is out-of-date

[0] http://web.mta.info/nyct/service/pdf/tacur.pdf

[1] Saying a train is "delayed" doesn't give me any useful information, because I already know that about half the trains are delayed. And since it doesn't tell you what the scheduled ETA was, telling me that it's "delayed" from the scheduled ETA is also pretty useless[2].

[2] If the train is scheduled to come in 20 minutes, but it's been delayed by five, that's different from if it's scheduled to come in 3 minutes, but has been delayed by 10. Those two situations are displayed identically on the BMT countdown clocks, with no way to distinguish between them.

[3] The official MTA party line is that they want to wait and do the really expensive, comprehensive, state-of-the-art overhaul. In reality, that means that they've been saying this for nearly thirty years, and have actively fought all attempts to provide quicker and cheaper ways of achieving the same end results.