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Train doors require GPS signal to open despite stations being underground (2014)

ciras.org.uk

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Re: Train doors require GPS signal to open despite stations being underground (2014)

#31

Post by sukilot »

sandworm wrote: post #17

So what happens in a power failure? I can see the need and advantage of a system to make sure that only the appropriate doors open at certain stations, but surely this could have been done with information at the local level. Barcodes, NFC, RFID ... to go with sats hundreds of miles in the sky augmented by repeaters is overly complex. Passengers are not cattle. I don't see why they cannot have local door control when…

Your claim needs evidence. A hypothetical murderer could open a door and push people out, no weapon necessary. In a fire, passengers could fall out a door onto third rail.

Re: Train doors require GPS signal to open despite stations being underground (2014)

#32

Post by pilif »

themartorana wrote: post #2

"...and the trains have needed to be rebooted." Nope. No thanks. Do not need my trains to be so "smart" that the only way to get them working properly is CTL-ALT-DELETE. Seriously.

I once had the opportunity to drive along in a locomotive here in Switzerland. En route, the computer has detected an issue in the engine, has restarted the whole machine and came back up fine.

This happened while driving at 160 km/h and if we had not seen the messages on the screen, nobody would have known.

That was seriously impressive and I wish I could do something like this. Not only did it properly detect the failure, it also rebooted and then came up correctly and still was aware of all the state needed to drive on.

If software works like that, I can live with it being used more and more.

Re: Train doors require GPS signal to open despite stations being underground (2014)

#33

Post by nemetroid »

hobs wrote: post #21

Why wouldnt this using something like radio waves in each station from a few sources, wouldnt it be super easy to tell your position fairly accurately with just a few radio sources? I did some googling and indoor localization systems can determine your location down to 3cm, I think that would be way more accurate than the 50m or so I have observed of GPS units while they moves around. And obviously they would be 1000…

I agree. The entire thing sounds a bit like running a web-based Javascript solution on an embedded system because that's the only technology you're familiar with.

Re: Train doors require GPS signal to open despite stations being underground (2014)

#34

Post by sukilot »

crazychrome wrote: post #15

> ... and trains have needed to be rebooted. Since when that default solution to any problem of any device embedded with CPU, is to reboot ? Welcome to the digital age!

Since the digital age started, aka when CPU was invented. Rebooting and erasing all rewritable memory gets the system into a known good state.

Re: Train doors require GPS signal to open despite stations being underground (2014)

#35

Post by kalleboo »

TillE wrote: post #9

The only advantage GPS would have is that you don't have to install something (eg, a powered RFID tag) in each station. And yet, they've had to install "GPS repeater beacons" to work around this problem. Sounds like a typical case of bad design.

The buses where I'm from started using the odometer to show the next station on a digital sign some time in the 90's. This ought to work even more accurately on a train.

Re: Train doors require GPS signal to open despite stations being underground (2014)

#36

Post by kalleboo »

hobs wrote: post #21

Why wouldnt this using something like radio waves in each station from a few sources, wouldnt it be super easy to tell your position fairly accurately with just a few radio sources? I did some googling and indoor localization systems can determine your location down to 3cm, I think that would be way more accurate than the 50m or so I have observed of GPS units while they moves around. And obviously they would be 1000…

Or an odometer (wheel revolutions) which is what buses often use and the technology is over 2000 years old[0] and quite cheap and reliable

[0] http://en.wikipedia.org/wiki/Odometer#Classical_Era

Re: Train doors require GPS signal to open despite stations being underground (2014)

#37

Post by cstross »

Sigh.

Someone tell Bruce Schneier his new movie plot terror threat[1] is here: someone homebrews a GPS signal transmitter to open all the train doors at rush hour ... preferably on the wrong side.

[1] https://www.schneier.com/essays/archives/2005/09/terrorists_...

Re: Train doors require GPS signal to open despite stations being underground (2014)

#38

Post by [deleted] »

ceeK wrote: post #16

I actually experienced this in St Pancras International last week! The train stopped in the station, but the doors didn't open for a good 5 minutes. The driver issued a statement stating that there'd be a slight delay before the doors opened. I recall thinking: what possible reason could there be for not opening the doors? Congestion? Electric failure? Well, turns out it's the most ludicrous one.

[deleted]

Re: Train doors require GPS signal to open despite stations being underground (2014)

#39

Post by tonyhb »

marbletiles wrote: post #26
marbletiles wrote: post #5

> Operation of Class 377 train doors require a (GPS) signal to identify that the train is in a station to allow the Driver to open the doors. Effectively this prevents the doors being operated in error when the train is not at a station and as such is a safety feature of the trains. Was there some epidemic of doors being opened outside stations that I missed? This smacks of a solution looking for a problem

Thinking about this some more, I still don't understand. If the goal was door safety, why not use the same release systems automatic trains (eg underground) have?

Yeah. It's a completely ridiculous idea. Almost as if the project manager had an idea and pushed it through without thinking about the repercussions.

If it's really a problem why not use the speedometer to figure out if the train is moving? Or why not use something like the MTA's wheel rotation sensors? The guy who wrote the signal code for MTA said that they use wheel rotations to calculate when to play audio messages in-train and in-station... those "There is a queens-bound train N stations away". It's a simple idea.

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