[fdr]

A once a generation refresh seems okay in my book. The Breda trains that came in 1996 were being phased out about twenty years into their tenure, most generally seem to think that is about reasonable a time to do something like that. I don’t see software related regimes as inherently that different.

Since I experienced 5.25 inch floppy disk era...and even the occasional bernoulli disk...we could simply say: the system had its run, replacement is reasonable. A lot of stuff had changed since then, and not just in storage media.

[mikewarot]

That ancient code is the crystalization of the knowledge of how to run, at the most basic level, all of the MTA. Emulating hardware is a good way to extend it's life while the decade long task of replacing it is underway.

Until you have directly used "legacy" machine that are mission critical, and understand how even a tiny error could cause the failure of a business and all the jobs that go with it, you can't avoid underestimating the true scale and scope of the problem.

[compuguy]

Here in the Washington DC area, our metro still has two series of rolling stock that date back to 1982 and 1987 (2k and 3k series). At the earliest they won't start retiring them in 2024 and 2025 at the earliest...

[jtbayly]

Wait, you’re suggesting replacing trains because the computers inside them are old?

[asveikau]

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.

[fdr]

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.

[thsksbd]

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

[fdr]

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.

[inferiorhuman]

Transit vehicles purchased with federal funds are required to meet a minimum service life (see below). For the Muni Metro you're looking at a minimum expected life of 31 years.

https://www.transit.dot.gov/sites/fta.dot.gov/files/2021-11/...

[jcgrillo]

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