Live data from Hacker News

‘The Trains Are Slower Because They Slowed the Trains Down’

villagevoice.com

61–70 of 243 posts

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#61
post #32

Earlier quoted context omitted.

It's already a thing, first example that comes to mind is line 14 in the Paris metro: https://en.wikipedia.org/wiki/Paris_M%C3%A9tro_Line_14

Line 1 is even more interesting as it was converted from manually driven operation to fully automated operation without without major interruption to passenger traffic. ( https://en.wikipedia.org/wiki/Paris_M%C3%A9tro_Line_1 )

And it was considered successful enough that they've started work on converting Line 4. After line 14 was put in service in 1998, RATP actually started drafting plans to convert lines 1, 4, 6, 7, 9 and 13.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#62

This would not be the first time that the MTA has willfully deceived the public by maintaining two sets of facts - the private set which reflects the truth and another set of facts that are used in discussion with the public. 15 years ago the MTA was caught maintaining two different sets of books - one internal that showed the agency had a surplus of cash and another set of books for the public which showed the agenc…

> The culture of this agency is rotten and its corruption endemic How does one realistically reform something like this?

You fire everyone.

However, if I remember correctly, they're unionized, which is why this hasn't happened yet.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#63
post #44

This article has a lot of text before getting to describing the problem. Summary: Train wreck 1995 and a installation of a safety-first, CYA response that slows down the trains and does not increase safety. Longer Summary: Train wreck in 1995. Maybe driver was asleep. Start installing new signals that not only automatically stop the trains when there is a train ahead (good idea and already in place), but also when go…

> Drivers go even slower than 45mph because the train is automatically stopped when going faster (as you would want to do if there was a train ahead) instead of just giving a warning and letting the train keep going. Is there any protection system that allows the maximum speed to be exceeded with just a warning? Certainly all those I can think of (TPWS, TVM, PZB, or something more modern like ETCS) have a given maxim…

That, and considering a speed limiter instead of stopping the train when traveling too fast. What good does it do to stop the train when going too fast instead of limiting it in the first place?

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#64
post #44

This article has a lot of text before getting to describing the problem. Summary: Train wreck 1995 and a installation of a safety-first, CYA response that slows down the trains and does not increase safety. Longer Summary: Train wreck in 1995. Maybe driver was asleep. Start installing new signals that not only automatically stop the trains when there is a train ahead (good idea and already in place), but also when go…

I agree with most of your summary, but I don't believe the article provided evidence that installation of signals to enforce a lower max speed "does not increase safety".

I'd speculate, without evidence, that it probably has increased safety. But maybe it's just a bad tradeoff, compared to other options.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#65
post #3

Earlier quoted context omitted.

But beyond a certain point slowing the trains gains little safety but (eg) pushes people back to the road where (in the UK for example) we spend 10x less to save a life than on the trains. Thus, overcaution on the trains will kill more people.

Wonder how much further you can take it. If you lose a little safety (trains) and take more people off the road, you increase the risk of a train accident. How many people go back to the roads after a train accident? Is the backlash greater (my 0 data thoughts would be that more people would return to the road then just if the train was slow). I heard somewhere that more people died through increased car accidents af…

You don't really need to propagate it all the way to actual lives lost. If there is an hour of life lost on a too safe train, that's a fraction of a life lost.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#66

Earlier quoted context omitted.

There was an automatic light rail to Docklands in London when I last visited. In 1991. Helsinki metro was planning to have automated trains when the western extension opens in 2014. It opened in late 2017, without automation because of technical difficulties. I have a hard time believing there will be much automated traffic on the roads here (with uneven surfaces, unclear markings, snow, and other traffic) before the…

Docklands opened in 1987 but is only GOA3 (the train runs automatically but requires a staff member responsible for departure & emergency situations). Port Island Line (Kobe) opened as GOA4 (fully automated) in 1981 followed by Lille Metro in 1983 and Vancouver's SkyTrain in 1985. The US has several GOA4 systems, though they're mostly airport shuttles and people movers (AeroTrain at Dulles, Monorail at Tampa, STS at…

> Wow, that's a bit ridiculous.

Less than what's happened with the London Underground Sub-Surface Railway, which is now on the third resignalling contract to get them to GoA Level 3.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#67
post #44

This article has a lot of text before getting to describing the problem. Summary: Train wreck 1995 and a installation of a safety-first, CYA response that slows down the trains and does not increase safety. Longer Summary: Train wreck in 1995. Maybe driver was asleep. Start installing new signals that not only automatically stop the trains when there is a train ahead (good idea and already in place), but also when go…

> Drivers go even slower than 45mph because the train is automatically stopped when going faster (as you would want to do if there was a train ahead) instead of just giving a warning and letting the train keep going. Is there any protection system that allows the maximum speed to be exceeded with just a warning? Certainly all those I can think of (TPWS, TVM, PZB, or something more modern like ETCS) have a given maxim…

There are... one of them is given in the article—which calls the current system "one-shot"—there exists k-shot variants which allow for at least k opportunities/warnings before automagically braking. The (apparent) reasoning behind the MTA not putting these (for some number k>1) was "safety," but the article states that, in general, the timing circuits are much more complicated therefore resulting in a higher cost.[0]

Additionally, a simple case would be to have circuits which do, after a certain point in time, force slow (but safe) braking into the required velocity---I could see problems with robustness here due to the specific application, but at least in theory this should be possible (we all know the difference between theory and practice, though).

On the general case, this all seems a little weird to me since it seems like such a trivial problem (increase error bands, etc), but may have some deeper reasons that aren't explained in the article(?). It's quite difficult to tell since the primary sources are not provided at any point in time.

---

[0] I'm reluctant to accept this claim since most of these things aren't done in an analog way, anymore. Timing is a matter of figuring out empirical constants and programming them in directly, which, while not totally trivial, seems to have roughly the same difficulty (amortized over all of the lights that need to be put in) as doing the timing for a 'one-shot' light.

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#68
post #39

Earlier quoted context omitted.

Money. The technology is not hard to create, but it does take a bunch of engineers time and effort to design it all (probably a mix of mechanical and computer work), and then more time to buy the equipment and install it. There is nothing off the shelf, even if some other subway gave them all the design (unlikely), it would still be hundreds of thousands of dollars per train to make it fit the New York trains.

> There is nothing off the shelf, even if some other subway gave them all the design (unlikely), it would still be hundreds of thousands of dollars per train to make it fit the New York trains. What? Alstom, Ansaldo STS, Bombardier, Siemens, and Thales all have off-the-shelf designs that they will happily sell. And I've probably forgotten some here. I realise none of these are American companies, and "Buy American" i…

That's the com system, but there are fully automated off-the-shelf systems (com, rolling stock, …). Two examples are Siemens's VAL (Lille, Taipei's Brown, Seoul's U-line, VAL tech has also been used in Lyon's D and Paris's 14 and 1) and Hitachi's AnsaldoBreda Driverless (Copenhagen, Taipei's Yellow, Milan 5, …).

The latter is very popular and getting deployed in several places right now: Honolulu, Thessaloniki, Lima 2, Rome C, …

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#69
post #49

Earlier quoted context omitted.

Nothing. Viennas subway has semi autonomous trains since 1960 or so. The driver just presses a “leave station” button after verifying nobody is stuck in the doors.

Stockholm metro has this as well but I wouldn't call it "autonomous", it's just a departure button to get the train moving faster. The driver still has to grip the vigilance device after a certain amount of time. According to https://en.wikipedia.org/wiki/Vienna_U-Bahn#Fifth_expansion_... it seems that vienna isn't driverless yet.

In Vienna it's fully automated between stations. The main reason it's not fully automated is because there are no automatically closing doors in the stations. U5 is going to get it though: https://www.youtube.com/watch?v=VBDqq7rwLE0

You can quite often see the trains operate fully automatic though when the drivers are changing shifts at the end of the line. The driver typically leaves and locks the train, lets it reverse itself and then the next driver continues: https://www.youtube.com/watch?v=0eyjqS9lvNA

Re: ‘The Trains Are Slower Because They Slowed the Trains Down’

#70

Earlier quoted context omitted.

> Drivers go even slower than 45mph because the train is automatically stopped when going faster (as you would want to do if there was a train ahead) instead of just giving a warning and letting the train keep going. Is there any protection system that allows the maximum speed to be exceeded with just a warning? Certainly all those I can think of (TPWS, TVM, PZB, or something more modern like ETCS) have a given maxim…

That, and considering a speed limiter instead of stopping the train when traveling too fast. What good does it do to stop the train when going too fast instead of limiting it in the first place?

The general principle in railway movement authority is that there's an easy fail safe: stop moving. If nothing moves, there can be no collision.

If something goes wrong? Stop the train. You can then figure out what went wrong and address it with no risk. Things shouldn't be going wrong, speeds shouldn't be being exceeded, etc.

Post reply on HN