The subway system used to be operated by different companies. To simplify greatly- the letter lines were a different company (BMT) to the number lines (IRT). That's why there are so few stations that allow you to transfer between letters and numbers, and why trains on lettered lines cannot run on numbered tracks, and vice versa. It's also why we have countdown clocks on numbered lines and not lettered ones- they use different technology.
There are even stories of one company intentionally obstructing the other. If I recall correctly, the BMT built track that they had no intention of using, just so that they could block the IRT from extending the 7 line beyond Times Square.
Sometimes I wonder why the subways fascinate me as much as they do.
> It's also why we have countdown clocks on numbered lines and not lettered ones- they use different technology.
This actually came up in a different thread, where I asked how the old technology could possibly prevent something as simple as countdown clocks. I never got a good answer when I said
> I don't care about the signal towers or how old the system is. The point is that the technology for identifying the location and speed of a few hundred giant hunks of metal moving around on fixed tracks is trivial and does not need to interact with the old system (or humans) at all. Just tag each train with a few RFID's, and stick in a few hundred miles of wiring into the tunnels.
>I mean, are you telling me for a 100 million dollars this couldn't be done?
> “The existence of this sleek digital interface barely hints at the investment that had to be made in terms of hardware and infrastructure to make this enormous public benefit a reality,” said Thomas F. Prendergast, President of MTA New York City Transit. “Think of Subway Time as the small tip of a huge iceberg. For a product of this quality to be available on the lettered lines, we will need to commit hundreds of millions of dollars and years of dedicated effort.”
> Automatic Train Supervision installation began in 1997. The system was activated in segments, with the substantial completion taking place in 2008. The project cost $20.8 million per year over 11 years, or $228.3 million in total.
I imagine (though I have no idea) that those millions of dollars are not used on countdown clocks- they're used to centralise all train operations in one building, with countdown clocks as a side-effect benefit.
There are even stories of one company intentionally obstructing the other. If I recall correctly, the BMT built track that they had no intention of using, just so that they could block the IRT from extending the 7 line beyond Times Square.
Sometimes I wonder why the subways fascinate me as much as they do.