Comment by Toxygene | Hacker News Reader

Comment by Toxygene | Hacker News Reader

I'm a developer in the Midwest and my team participated in the signaling contest for the MTA Genius Challenge[1]. I handled gathering the raw data from our hardware and generating visualizations for testing, troubleshooting, and eventually presentation. Using a variety of hardware (ranging hardware on the train and through the subway tunnel, Ulta-wideband[2] transmitters for sending data, ect), we developed a Communications-based train control[3] system that would allow for moving block signaling[4].

It was a fascinating few months of problem solving and troubleshooting. I have fond memories of sitting at a folding table on the 7th Ave platform during a cold week in January.

That said, I don't envy those still working on this project. There are so many problem -- old signaling hardware that breaks down frequently and has to be manufactured by the MTA because no one produces the parts anymore, slower train speeds, track fires, train malfunctions, passenger-related delays... the list goes on and on. I hope they're able work it all out because I really enjoyed riding and working on the subways, even if only for a couple of months.

1 - https://www.youtube.com/watch?v=GMjSi0ftLjA

2 - https://en.wikipedia.org/wiki/Ultra-wideband

3 - https://en.wikipedia.org/wiki/Communications-based_train_con...

4 - https://en.wikipedia.org/wiki/Moving_block

why not just use the same signals as the hong kong metro? which is leagues better. This seems like a solved problem.

I don't understand why transit agencies seem to reinvent the wheel when it comes to signalling, Caltrain spent $250M+ on a custom CBOSS PTC signalling system.... which I think they recently abandoned in favor of a standard signaling system.

The precursor agencies and corporations in New York developed signalling systems that were cutting edge in the '30s, since there weren't a lot of multinational signalling suppliers back then, nor were there a lot of metro systems.

The current situation is what happens when you don't fund a replacement for several decades.

It's important to note historical context.

The New York subway system was built in spurts up to about the 1950s. This means that large sections of it, tens of miles long, become due for renewal at the same time. Contrast this to MTR, which opened short segments in several phases.

There was also a period stretching probably from 1930-1980 where maintenance on New York's subway was completely deferred. No maintenance or replacement was done for the signals at all. So a lot of what has been happening up until now is not only meant to replace stuff that is due for replacement, but stuff that has been overdue for replacement for decades. It takes a lot of time on a 24/7 railway's schedule to fix such a large backlog. And they usually only refresh the backlog with stuff that is both compatible with the entire existing fleet, which is thousands and thousands of train cars.

Coincidentally, since MTR was first developed in the '70s, those signals are due for replacement right about now. From what I have heard MTR is starting to have a much higher rate of failure than previously, which would make sense if the signals are getting old.

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