[8260337551]

Can someone explain what triggers a note? I don't understand from the explanation on the site. Is it whenever a train on the line crosses a predetermined geo-location?

What do the technical details look like behind this to get the data?

[mplanchard]

I think every line’s route is normalized to the same length of time, and a note is played when trains are at stations along that route.

If you turn on the map portion of the UI, you can see where the stations are. This is why there’s a dearth of notes over the east river (no stations on the water), other than the one stop at Roosevelt Island, for the F or the M, depending on the time of day.

[kylecazar]

If you switch to bar view on the bottom, it will be more apparent.

Each line in that view represents a subway line's route. Each note/dot along each of those lines is a train that is currently at that stage of progression through the route (based on geo location from the MTA).

They assigned a different instrument to each subway line.