SFMTA's train system running on floppy disks; city fears 'catastrophic failure' • Hacker News Board

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#161

Post by yonran » Wed, Apr 10, 2024, 10:33 PM UTC

iancmceachern wrote: post #63

I emailed them. I live I'm SF. This is the sake, solved, problem we have in the machine tool world (milling machines, lathes, etc). Similar to old keyboards, you can just buy and use a floppy emulator. They emailed me back, they said that the floppy thing makes a good headline but is really just the tip of the iceberg. It's really the whole system that's like this at every layer, it needs replacing they say.

The real scope of the project is a mind-boggling $600 million to track the light rail trains inside and outside the tunnels and to control the trains inside the tunnels. Divided by the 250 light rail vehicles (apparently does not include historic streetcars), it works out to $2.6 million per car. Plus $36M for consulting (2023-11-07 board presentation from the documents that I linked earlier https://www.sfmta.com/sites/default/files/reports-and-docume...).

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#162

Post by jcgrillo » Wed, Apr 10, 2024, 10:37 PM UTC

asveikau wrote: post #149

jcgrillo wrote: post #143

Earlier quoted context omitted.

Wait, what? If this thing boots from a floppy, and that floppy has a checksum on it, and the boot sequence involves loading the checksum and the rest of the floppy contents into RAM and computing the checksum, corruption detection would be near instantaneous and the remediation would be as quick as it takes to eject the corrupted floppy, grab another floppy copy from the bin, plug it in, and flip the on switch. So th…

Let's say it's not just booting from it, but constantly reading. Let's say no one implemented the checksum. Edit: I forgot that floppies have a crc check, my bad. Let's say the machine that can write the new disk is physically far away from the machines that read them. (Or the guy with a stack of new disks -- which are harder to find every year -- his office is some distance from the control machine).

I guess I assumed it was only reading from the floppy, not also writing to it.. that doesn't seem like it would last very long at all without encountering errors (at least based on my memories of reusing floppies until they were completely worn out)

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#163

Post by thsksbd » Wed, Apr 10, 2024, 10:45 PM UTC

fdr wrote: post #155

asveikau wrote: post #144

Earlier quoted context omitted.

I think they're just saying parts should be periodically replaced across the board on that timeframe, and using the fact that the trains are being swapped out as an example. The Breda trains are still running some percentage of the fleet however. I rode in one today.

That’s right. System refreshes are a fact of life, especially if one is parsimonious in using what works until obsolescence. There are downsides of doing things that way, but I don’t see it inherently more defective than other approaches, such as some kind of continuous refresh that has a conceit of keeping a system “modern” in perpetuity.

But twenty years for a train seems very low. My daily driver is 12 years old, I thrash it every morning and never gives me problems. I live in the snowbelt.

By comparison a train is vastly over-engineered and has an electric drive train. Sure stuff will need replacing but a train should last 40 years at least

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#164

Post by wpietri » Wed, Apr 10, 2024, 10:49 PM UTC

J_Shelby_J wrote: post #153

wpietri wrote: post #66

Earlier quoted context omitted.

I think there are a bunch of things causing this problem. Off the top of my head, some factors: - chronic underfunding - we all know how problems build up when maintenance is deferred - waterfall planning - Mary Poppendieck has a nice talk on how much trouble this causes: https://www.infoq.com/presentations/tyranny-of-plan/ - political point-scoring - blame-oriented cultures discourage experimentation and incremental…

I’m a liberal democrat, but it’s clear that one party politics is not tenable. There has to be an option to the status quo that you can vote for to incentivize competency in government. But with the state of national politics it would be almost impossible for a republican to win in most of urban America. So that leaves just primary challengers from within the Democratic Party which is very difficult. So urban politic…

I totally agree we need more actual competition, and also agree that national polarization plus a first-past-the-post system makes that unlikely in the near term.

I would also love to see widespread use of RCV, but as a San Franciscan I don't think it has done tons to fix the problem of complacent political machines here, so we're going to have to do more.

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#165

Post by temp112123 » Wed, Apr 10, 2024, 10:52 PM UTC

dblohm7 wrote: post #156

HumblyTossed wrote: post #36

> This system was designed to last 20 to 25 years. SFMTA's director Jeffrey Tumlin said upgrading the system will take another decade and cost hundreds of millions of dollars. This is the problem, not that they're using a floppy. This isn't web dev where you get to rewrite everything every 6 mos. Systems have to have decades long life cycles BUT THEY EVENTUALLY NEED TO BE REPLACED and that's not happening quickly eno…

I think it's worth pointing out that 5.25" floppies were already well out their way out in 1998, already.

[dead]

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#166

Post by krallja » Wed, Apr 10, 2024, 10:53 PM UTC

bobthepanda wrote: post #117

kion wrote: post #75

Earlier quoted context omitted.

I looked into this last year, a significant part of the cost is in new hardware, both on the vehicles, but also sensors spread through the system. They all need commercial grade RF systems that allow for 2 way signaling communication and integration into the vehicles control systems.

also they need to be rated for the operating environment. you can't stick any random part from newegg in there. Tesla used non-automotive grade touchscreens in some cars and so they died early: https://www.thedrive.com/tech/27989/teslas-screen-saga-shows... Automotive grade has very high requirements: > Grade 0: High Temperature Operating Life (HTOL): +175C for 408 hours. High Temperature Storage Life (HTSL): +175C f…

I’ve noticed that my car’s touchscreen operates at a very high temperature at all times - almost hot enough to burn skin, which seems like a weird choice for something designed to be touched by skin.

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#167

Post by jcgrillo » Wed, Apr 10, 2024, 10:53 PM UTC

thsksbd wrote: post #163

fdr wrote: post #155

Earlier quoted context omitted.

That’s right. System refreshes are a fact of life, especially if one is parsimonious in using what works until obsolescence. There are downsides of doing things that way, but I don’t see it inherently more defective than other approaches, such as some kind of continuous refresh that has a conceit of keeping a system “modern” in perpetuity.

But twenty years for a train seems very low. My daily driver is 12 years old, I thrash it every morning and never gives me problems. I live in the snowbelt. By comparison a train is vastly over-engineered and has an electric drive train. Sure stuff will need replacing but a train should last 40 years at least

https://www.wbur.org/morningedition/2016/03/07/mbta-signal-m...

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#168

Post by Smoosh » Wed, Apr 10, 2024, 10:58 PM UTC

ericmcer wrote: post #91

SF is a joke. 20 years of being one of the richest cities in the world (probably in the history of human beings) and it comes out worse than it was before.

That assessment can probably be scaled up to the USA as a whole.

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#169

Post by fdr » Wed, Apr 10, 2024, 11:00 PM UTC

thsksbd wrote: post #163

fdr wrote: post #155

Earlier quoted context omitted.

That’s right. System refreshes are a fact of life, especially if one is parsimonious in using what works until obsolescence. There are downsides of doing things that way, but I don’t see it inherently more defective than other approaches, such as some kind of continuous refresh that has a conceit of keeping a system “modern” in perpetuity.

But twenty years for a train seems very low. My daily driver is 12 years old, I thrash it every morning and never gives me problems. I live in the snowbelt. By comparison a train is vastly over-engineered and has an electric drive train. Sure stuff will need replacing but a train should last 40 years at least

I wouldn't call myself as particular on train maintenance...but consider that these trains are run more or less continuously. You thrash your car in seasonally tough conditions every morning, but these drive all day and most of the night. So, I'm not sure if the comparison is apt on these grounds.

A cursory search suggests that quite a few manufacturers design for light rail car lifetimes of 25-30 years, not forty. These tend to be of European origin, which tracks San Francisco switching from an Italian to a German vendor. I don't see evidence that it's a common practice to significantly extend the tenure of those devices there nor here.

Funnily enough, I see no problems with the Breda trains personally as a passenger. But once they've shaken out the major bugs, the Siemens train reliability is anticipated to be triple or more. It may not make sense to design a traincar for a fifty year term.

Re: SFMTA's train system running on floppy disks; city fears 'catastrophic failure'

#170

Post by jcgrillo » Wed, Apr 10, 2024, 11:02 PM UTC

JoyousAbandon wrote: post #121

Absurd errors in this article. Starting with: "it was from an era that computers didn't have a hard drive" Absolute BS. Pretty much every computer had a hard drive in 1998, and most had CD-ROM. Then they referred to the 3.5" disk as a "5-inch floppy."

Saying it more times doesn't make it more true.

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