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How we slowed the subway down

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Re: How we slowed the subway down

#51

Post by jazzyjackson »

jimmyswimmy wrote: post #35
hristov wrote: post #12

It is actually bonkers that in this day and age the NYC subway cannot install accurate speed gauges on their trains. You can get an accurate bike speedometer for $20 on amazon, but the NYC subway cannot provide an accurate speedometer for train carrying a couple of hundred people. It is true that trains require more rigorous standards, but it is not a difficult problem. For example you can put a sensor on the electri…

While i agree that it is surprising that MTA continues to use archaic technology, I don't the solution is nearly as simple as you pose it. Hardware engineering is hard, and in-service engineering of complex systems desiring near 100% uptime is challenging. The sensors must not simply survive a dirty, dusty environment, they must work perfectly with no glitches and for long periods between maintenance. And if they do…

> I assume it's a budget limitation driving slow progress.

The budget is enormous, it's just being embezzled from top to bottom.

Re: How we slowed the subway down

#52

Post by themitigating »

dzdt wrote: post #3

After an operator-error derailment on the commuter rail line I frequently ride, the response of the NTSB was to require the railroad de-prioritize on-time performance and increase schedule times. As a frequent rider on the route I would much rather have my 15 minutes per day back and risk a once-per-century fatal accident. But the risk-averse bureaucracy we've built doesn't make such calculations with a balance like…

But if you were in that accident or a parent/friend in it you'd have the opposite opinion and demand "the politicans make things safer "

You're just a selfish npc

Re: How we slowed the subway down

#53

Post by concordDance »

gruturo wrote: post #7
hristov wrote: post #5

Earlier quoted context omitted.

"Sure you save some lives but how many will be late!" I do not like this math. For example the accident may not be once per century. And it is good for the bureaucracy to be risk adverse if it comes to my life. The answer is that they should improve the technology so that the system is safe and faster.

If OP's subway carried 80k people per day (and I guess this could be conservative), and they are all delayed 15 minutes, the overall wasted time equals 1 lifetime per month. I'm all for improving the technology, but in the meantime the math should absolutely be done, at least to ensure the temporary fix isn't worse than the problem.

You need to adjust for the QALY level of riding a train compared to the rest of people's lives. Train riding isn't much fun, but it's much better than being dead.

Your point probably still holds though.

Re: How we slowed the subway down

#54

Post by concordDance »

nostromo wrote: post #37
hristov wrote: post #5

Earlier quoted context omitted.

"Sure you save some lives but how many will be late!" I do not like this math. For example the accident may not be once per century. And it is good for the bureaucracy to be risk adverse if it comes to my life. The answer is that they should improve the technology so that the system is safe and faster.

> "Sure you save some lives but how many will be late!" You make this trade off every day without admitting it in such stark terms. Every time you drive, bike, or fly to a destination you’re choosing speed at an increased risk of injury or death.

Note that flying is safer than walking.

Re: How we slowed the subway down

#55

Post by Symbiote »

hadlock wrote: post #39
jimmyswimmy wrote: post #35

Earlier quoted context omitted.

While i agree that it is surprising that MTA continues to use archaic technology, I don't the solution is nearly as simple as you pose it. Hardware engineering is hard, and in-service engineering of complex systems desiring near 100% uptime is challenging. The sensors must not simply survive a dirty, dusty environment, they must work perfectly with no glitches and for long periods between maintenance. And if they do…

My 1955 Citroen (designed in 1933) has the original speedometer and speed sender cable. It's accurate (GPS tracked) to within 2-3km/h. This is with nearly 70k miles on the clock. This is the same mechanism Citroen used in their 2CV from 1946 until 1992. Most Model A Fords from 1929 have their original speedometer (which works fine, might need greasing every few decades though). With tens of thousands of miles on them…

For what it's worth, a metro train does around 100,000 miles per year.

Re: How we slowed the subway down

#56

Post by concordDance »

poslathian wrote: post #16
dzdt wrote: post #3

After an operator-error derailment on the commuter rail line I frequently ride, the response of the NTSB was to require the railroad de-prioritize on-time performance and increase schedule times. As a frequent rider on the route I would much rather have my 15 minutes per day back and risk a once-per-century fatal accident. But the risk-averse bureaucracy we've built doesn't make such calculations with a balance like…

I often wonder how we might estimate how much of the surplus created by economic growth and technology has been hoovered up by “alarp” in its many forms. I’m scared of the answer, and of the people who wouldn’t see a problem with it.

For those wondering:https://en.m.wikipedia.org/wiki/ALARP

As Low As Reasonably Practical

Re: How we slowed the subway down

#57

Post by rtpg »

dzdt wrote: post #3

After an operator-error derailment on the commuter rail line I frequently ride, the response of the NTSB was to require the railroad de-prioritize on-time performance and increase schedule times. As a frequent rider on the route I would much rather have my 15 minutes per day back and risk a once-per-century fatal accident. But the risk-averse bureaucracy we've built doesn't make such calculations with a balance like…

What if we actually just operated trains safely, made improvements to the system, and then sped things up _because we improved the safety to make it possible?_

"We risk crashes or make everything slow" is a false choice when we're talking about years-long perspectives. Especially given that there are lots of contributors to throughput and slowness.

Re: How we slowed the subway down

#58

Post by lifeisstillgood »

My takeaway: imagine we decided the enforce no crashes on roads. The second a driver comes too close behind another car or breaches speed limits, the car enforces their brakes on.

Yeah I can see how the knock on tailbacks and flow will make roads insane.

Re: How we slowed the subway down

#59

Post by rocqua »

woodruffw wrote: post #40
hristov wrote: post #12

It is actually bonkers that in this day and age the NYC subway cannot install accurate speed gauges on their trains. You can get an accurate bike speedometer for $20 on amazon, but the NYC subway cannot provide an accurate speedometer for train carrying a couple of hundred people. It is true that trains require more rigorous standards, but it is not a difficult problem. For example you can put a sensor on the electri…

My understanding from TFA is that this isn’t the problem at all: most (all?) of the modern trainsets do have speedometers that the conductor can read. The problem is not measuring the speed; it’s that the city’s signaling scheme no longer matches the handling conditions of the trains that run over it. In other words: the conductor might be operating the train at a perfectly reasonable speed according to their accurat…

From the article:

Unfortunately, thanks to a combination of poor design choices and poor upkeep, many of these speedometers have proven to be wildly unreliable. So, as train crews navigated the increasingly speed-controlled subway of the aughts, they not only had to build uncertainty around signal design, but equally about the accuracy of their on-train equipment.

In other words the problem is both inaccurate signals and inaccurate speedometers. The combination requiring operators to be much more careful, and making them lose faith in their data. Exacerbating this is that signal trips caused by faulty timers were still blamed on operators. Making them also lose faith in management. Presumably, this wasn't good for the relationships between management and unions, hence probably contributing to strikes.

Re: How we slowed the subway down

#60

Post by interstice »

jimmyswimmy wrote: post #35
hristov wrote: post #12

It is actually bonkers that in this day and age the NYC subway cannot install accurate speed gauges on their trains. You can get an accurate bike speedometer for $20 on amazon, but the NYC subway cannot provide an accurate speedometer for train carrying a couple of hundred people. It is true that trains require more rigorous standards, but it is not a difficult problem. For example you can put a sensor on the electri…

While i agree that it is surprising that MTA continues to use archaic technology, I don't the solution is nearly as simple as you pose it. Hardware engineering is hard, and in-service engineering of complex systems desiring near 100% uptime is challenging. The sensors must not simply survive a dirty, dusty environment, they must work perfectly with no glitches and for long periods between maintenance. And if they do…

Is there a term for using multiple redundancy and statistics to solve issues, for example using 5x 99% reliable sensors rather than a single 99.99% sensor that costs 100x more?
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