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How we slowed the subway down

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Re: How we slowed the subway down

#81

Post by psychphysic »

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…

I believe it is actually a hard problem but there is a good solution being explored on the UK.

Read the rails like a card magstrip.

Trains first traverse the track scanning the entire length in detail with careful speed and location tracking.

Then trains can subsequently pattern match to the rail for location and speed.

The rails can also be coded with info like patterns although that's not generally needed. Trains get loaded with info about the track they'll be on and then can monitor progress themselves.

Re: How we slowed the subway down

#82

Post by Tokkemon »

pantalaimon wrote: post #45
mildchalupa wrote: post #28

One of the things that I find interesting in terms of long lasting standard or infrastructure development is that small variations in design choices early in a system result in radically different performance down the line. For instance the width or guage of a train track will greatly influence the carrying capacity and the size of objects transportable via rail. Same for the size of lane of road. Infrastructure, and…

The subway is actually a systems that is easier to change than others (unless you talk about the physical dimensions of the train) since it’s an isolated system and lines are usually separate too, so you don’t have to change it all at one.

Sure, but the New York Subway is the most interlined metro system in the world. You have to essentially change everything at once, or at least go trunk line by trunk line, or run two separate systems concurrently. None of which are easy options.

Re: How we slowed the subway down

#83

Post by Tokkemon »

A part of this story is how during Andy Byford's tenure, one of the biggest thrusts to his work was to fix this problem. He aggressively started studying and revising the timers to speed trains up, and it seemed to have worked. Of course, he was pushed out by Cuomo and then the pandemic happened so much of those gains seem to be short-lived.

Re: How we slowed the subway down

#84

Post by lifeisstillgood »

rocqua wrote: post #71
lifeisstillgood wrote: post #69

Earlier quoted context omitted.

I am however convinced by the "less cars, not self driving cars" argument. Urban redesign, reclaiming back some of the on average 1/3 of city surface area dedicated to cars / roads, more reliable public surface transport (I mean are we seriously asking "can we increase the likelihood of a subway crash in order to increase capacity" instead of asking "why don't we have hundreds or thousands more buses on the roads"? T…

In America, you are presumably correct, though it is somewhat of a false dichotomy. In less car based countries like my home country the Netherlands, there isn't as much room for 'less cars' (though still plenty, just nowhere near as bad as America). Hence self-driving cars here are more important. Besides the solution in America is likely to be both less cars and self driving cars. So it's not like self driving cars…

The problem (as I see it) was s not R&D, it's human nature. If there is a possible self driving car we can put things off, imagine a different mix etc.

Almost all of the climate chnage debate is really (excluding the fringes) not "is climate chnage real" but "exactly how much do I have to do to fix it".

An analogy is I don't dispute that I am overweight, and that will impact my lifespan, but t there is a debate on whether that means a calorie controlled plant based diet from tonight along with four hours in the gym each day, or I "make an effort to cut down".

Imagine AOC and Greta Thunberg as the personal trainers, and Bjorn Lornborg as the CEO of low calorie beer and no-salt chips LLC.

I think I have wondered off the point - but essentially we have within us the solution to all our ills. Politics is just the voices in our heads as we try to talk ourselves into going to the gym and sticking to a budget.

Re: How we slowed the subway down

#85

Post by steveBK123 »

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…

Don't forget WET environment. Due to the closeness to the surface and the era most of the tunneling was done, there's not just high humidity but actual water in the tunnels and stations quite often.

Re: How we slowed the subway down

#86

Post by rightbyte »

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…

> For example you can put a sensor on the electrical motor that will accurately measure motor position.

That is a spring mass system. Oscillations at the motor might or might not move the wheels. You want to measure at the wheels.

Also the play in the driveline messes up speed measurements.

Re: How we slowed the subway down

#87

Post by kylehotchkiss »

This plus the well-documented safety issues happening on public transit across the country will keep the personal vehicle market strong for decades to come. There’s no future in US where public transit is so good that it takes a notable amount of cars off the road until we can culturally conquer hard problems like these (like close down the line for 3 months to improve) and actually police the systems (fun fact - almost every big city in india has to go through metal detector and bag though x-ray to ride the metro, I’d love this in US)

Re: How we slowed the subway down

#88

Post by akgerber »

gambiting wrote: post #75
Symbiote wrote: post #55

Earlier quoted context omitted.

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

So do most normal trains, and they all have speed gauges that work fine, rain snow or dust. Clearly the technology exists.

NYCT was, until this year, operating R32 trainsets still limping along from the 1960s that were repeatedly life-extended as newer (1970s) train types experienced structural failures & delivery of their planned replacement trains was repeatedly delayed. It's obviously possible to maintain old trains, but generally expensive & challenging, especially when they're still doing 100,000 miles a year, and things clearly slipped.

Especially because the trains were operating well past their planned lifespan because their replacements were ordered but not delivered, so the major overhaul that would that would normally be done to life-extend a train kept running for decades didn't happen.

Re: How we slowed the subway down

#89

Post by ajsnigrutin »

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…

So.. what tech do normal, above ground trains use?

Re: How we slowed the subway down

#90

Post by Symbiote »

Gordonjcp wrote: post #80
Symbiote wrote: post #55

Earlier quoted context omitted.

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

So, considerably less than the average articulated lorry, or indeed Skoda Octavia?

No, very much around the average for an articulated lorry.

But metro trains stop and start every 2-5 minutes all day, last 40+ years, but also travel on a very smooth "road".

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