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Comment by jmward01 | Hacker News Reader

I read once that a huge issue with US metro is our over the top strength requirements. I wonder if that is still true. It is clear that Europe/basically anywhere has far more expertise and success in this than we do. Too bad it isn't as easy as 'we accept all country xxx regs and can start buying their stuff/using their designs'. I'm not that naive to think that is really a possibility, or that doing that would solve the other massive issues with US mass transit, but we can dream of transit like Tokyo can't we!

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The car strength requirements only apply to mainline rail, not rapid transit like BART which runs on dedicated rails. And even on mainline rail, the FRA now accepts Europeans rolling stock as of a few years ago.

That being said, change is slow, and very few agencies have taken advantage of the new rules

If US doesn't accept say Swiss products/designs then there is some serious flaw in that process (probably stemming from protectionism/corruption)

There's more to it than that. Our freight trains are much larger, heavier, and longer than swiss/European freight trains. It's not unreasonable to think that a passenger train sharing track space with North American freight trains would need to be more heavily built, if withstanding a collision is a goal.

There are other options. Positive train control is better than strong cars - train control means the trains can't crash in the first place (they can still derail, but you can't run into a slow/stopped train in front of you as the train will automatically stop if it cannot verify there is no train on the track in front of it). This is now mandatory in the US (with a lot of fine print exceptions).

Yes, because PTC systems never fail. Ugh.

PTC generally is designed to fail safe, so it will stop the train if something might be wrong. Nothing is perfect, but everything has a compromise and strong trains have a lot of negatives - they cost more, use more energy (read global warming as it there is normally some non-clean energy in the mix).

The hierarchy of controls suggests preventing collision

Swiss trains from Stadler are in fact selling rather well in the US recently (Caltrain, e-BART, New Jersey Transit, Austin, Dallas, and most recently Metra in Chicago)

That Metra project looks interesting, they are buying battery powered trainsets: https://metra.com/newsroom/metra-buying-battery-powered-trai...

45-65 miles range, and 20-30 minutes to charge 20->80%. Better than I would have expected, and certainly could work well on shorter routes where full electrification is impractical. Sounds like it will be built in the US as well.

Trains in Europe don’t have one engine pulling 200 cars stretching back for more than a mile.

> I read once that a huge issue with US metro is our over the top strength requirements. I wonder if that is still true. It is clear that Europe/basically anywhere has far more expertise and success in this than we do.

No, our trains are just waaay shorter - around 740-835 meters and a maximum weight of 2.200 tons [1].

US trains however? 3.6 km regular length limit [2], with the record being held by a 6.5km long and 48.100 tons weight. Even just at shunting, the forces in play are so much larger than here in Europe.

[1] https://die-gueterbahnen.com/news/zahl-des-tages/4.html

[2] https://www.uirr.com/en/news/mediacentre/2286-the-optimal-le...

[3] https://zmodal.com/2020/04/30/trains-are-longer-and-heavier-...

When you mean strength, what are you referring to?

I assume they mean this: https://en.wikipedia.org/wiki/Buff_strength

> Buff strength is a design term used in the certification of rail rolling stock. It refers to the required resistance to deformation or permanent damage due to loads applied at the car's ends, such as in a collision. Particular emphasis on buff strength is placed in the United States, with buff strength requirements there being higher than in Europe.

Never heard of it before either.

> such as in a collision

Really the worst-case scenario for a train crash is a collision on the side, because carriages are not built for it. This is the main reason why the Eschede train disaster [0] killed 101 people - the train "folded" because part of a broken wheel had flipped a railroad switch underneath the moving train. Then the folded carriages crashed sideways into a bridge.

https://dims.apnews.com/dims4/default/0fe6b8a/2147483647/str...

[0] https://en.wikipedia.org/wiki/Eschede_train_disaster

Europe doesn't get quite the train length that you see in the US. Also automatic latching versus manual latching on train cars in the US. The US was first to bump latch cars smacking them into one another.

Yes, but that should not matter on lines where passenger traffic is not mixed with freight one.

US rules (until recently) required heavy dust stock if there was the possibility of the trains meeting, even if the don’t run at the same time.

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