Oh, you wanted to get off the train? Tough shit, GPS is out.
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tl,dr: Some trains in the UK use GPS to check whether they are really in a station before they let you open the doors. Unfortunately, some stations are underground.
Money quote:
The location of the train then needs to be inputted into the TMS, allowing the doors to open. In some instances, even this will not release the doors, and trains have needed to be rebooted. This can take in excess of five minutes, leaving passengers on the train without an exit route.
I like technology as much as any IT guy, but who the fuck thought that would be a good idea? What's wrong with the tried-and-trusted method of "Engineer pushes a button, doors are allowed to open"?
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tl,dr: Some trains in the UK use GPS to check whether they are really in a station before they let you open the doors. Unfortunately, some stations are underground.
Weird. Our buses and trams use GPS to send updates on their position (so you get an ETA at most stations), but door control is fully under driver's control.
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Operation of Class 377 train doors require a Global Positioning Satellite (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.
...because engineers opening the doors over cliffs, lakes, etc. leading to the deaths of many passengers was once a common problem?
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I bet when the doors don't work, it's conductors sabotaging them to prevent them from being replaced by Raspberry Pis.
... wait, are Tube conductors unionized?
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wait, are Tube conductors unionized?
Tube trains don't have conductors; all the ticket checks are done by turnstiles.
The drivers have a union though; you might be thinking of that.
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Apparently this is because their trains are too long for their station platforms. And they couldn't be arsed to build longer ones. Or shorter trains. Or one of the like ten technical solutions that wouldn't require GPS reception in tunnels.
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Here in the US, if a train has a single crew member who drives and does other stuff, that person is called a train conductor.
I care not for your deviant British terminology.
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Weird. Our buses and trams use GPS to send updates on their position (so you get an ETA at most stations)
Ours have infrared beacons at every traffic light for that. And also for making everybody at the next set of lights two kilometers away wait until the fucking bus has finally driven past.but door control is fully under driver's control.
As it should be.
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Given the design brief, what exactly was wrong with having a simple beacon on each station announcing exactly which station it is?
Perhaps even including the size of the platform, and other such useful info.The in-cab signal aspect repeaters work that way FFS.
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Given the design brief, what exactly was wrong with having a simple beacon on each station announcing exactly which station it is?
Apparently they have that too, because GPS isn't precise enough even when it does work to tell the train what side of the platform it's on. I have no idea why they need GPS at all then. It's not like a local train would get lost or use a shortcut to skip a station or something.
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ten technical solutions that wouldn't require GPS reception in tunnels.
That would, presumably, be one of the "ten technical solutions that wouldn't require GPS reception in tunnels." That's not acceptable; it's too likely to actually work.
Edit: Oops! How'd I manage to mangle the quote so badly. The quote was supposed to be
what exactly was wrong with having a simple beacon on each station announcing exactly which station it is?
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Idiots. Utter idiots.
GPS is at best a 10m circle. (I forget if it's a radius or diameter)
If you need greater precision than that, GPS cannot work.I mostly use GPS as an atomic clock.
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There are concerns that this could delay an emergency exit if an incident were to occur, leaving passengers at risk.
I am really, really hoping the doors have a big red handle somewhere labelled "emergency unlock", and that it doesn't depend on any software to work.
Surely a door that locks several hundred people inside a small space must pass some emergency standards, right?
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I am really, really hoping the doors have a big red handle somewhere labelled "emergency unlock", and that it doesn't depend on any software to work.
Yes they do. But good luck getting people to use it properly in a genuine emergency.
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I am really, really hoping the doors have a big red handle somewhere labelled "emergency unlock", and that it doesn't depend on any software to work.
It's green. The red handle is the “stop the train now” one.
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I have no idea why they need GPS at all then. It's not like a local train would get lost or use a shortcut to skip a station or something.
Trains do get lost in the states apparently. As in they lose the paperwork on which route it was on and have no idea where it currently is.
We have GPS on the stuff we put onto trains, but I've not known it to be used for controlling doors. All it's used for for us is for displaying where all the trains are/have been on a map (and optionally mapping signal strength/network availability) and sometimes for determining which SIM cards to use on (e.g.) cross-border US/Canada or European routes
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If we need something to tell the driver when to open the doors, can we not have, say, sensors on each door to detect whether there's a platform outside.
If my car can tell whether there's a wall behind me*, a train can be fitted with a sensor under the door to tell whether there's an object resembling a platform outside it.
*well actually mine can't, because it's quite an old car, but you know what I mean.
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Does it even need to be that complicated?
Give the driver a button that enables the doors.
Is the train moving? Yes. Button disabled.
The train's stopped? Excellent. Button enabled.
Now the train's moving again? Button disabled.That's how I assumed they worked already to be fair.
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Is the train moving? Yes. Button disabled.
The train's stopped? Excellent. Button enabled.
Now the train's moving again? Button disabled.Easy there. You're starting with that fancy computer speak again that common folk don't understand.
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Trains do get lost in the states apparently.
I know there's an explanation for this, but it made me chuckle anyway.
Filed under: carefully backtracking our steps
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Here in the US, if a train has a single crew member who drives and does other stuff, that person is called a train conductor.
No. You are just wrong. They are called 'train engineers', and though 'driver' is more customary in the UK, NYC also generally calls their subway train operators 'drivers'.
A train conductor is someone who is involved with train duties, but not in operation of the train. Such as, taking tickets and etc.
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GPS is at best a 10m circle. (I forget if it's a radius or diameter)If you need greater precision than that, GPS cannot work.
Rubbish. Surveyors use GPS all the time with accuracy of under 1/16". It doesn't work that well underground though. ;)
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I know there's an explanation for this, but it made me chuckle anyway.
What he described is not "lost", it's "we don't know where it is".
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In some instances, even this will not release the doors, and trains have needed to be rebooted. This can take in excess of five minutes, leaving passengers on the train without an exit route.
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<erno> hm. I've lost a machine.. literally _lost_. it responds to ping, it works completely, I just can't figure out where in my apartment it is.
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That illustrates my point, even though his terminology is off. He knows it's in his apartment. Process of elimination will discern the location.
I've known more than one person where that is an actual potential issue.
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Surveyors use GPS all the time with accuracy of under 1/16".
Yes, if the receivers aren't moving for an hour or so. Or a land-based base-station is being used. Neither of which apply to a moving vehicle using bog-standard GPS receivers.
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That illustrates my point, even though his terminology is off.
Sorry, couldn't find chat logs of railway personnel talking about losing trains at such short notice.
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Sorry, couldn't find chat logs of railway personnel talking about losing trains at such short notice.
It would still illustrate my point. Trains don't just wander off. They're generally constrained by tracks. It's not as if you have to go looking through forests or something, unless those forests have tracks running through them.
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Trains don't just wander off. They're generally constrained by tracks.
Generally. Not always.
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Generally. Not always.
If your trail derails, 1), that's not what we were talking about, and you're likely to rediscover it in a right hurry, and 2), it's not likely to go anywhere else other than strictly local motion (e.g., down a hill).
Also, pendantry.
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Hey, no need to fight me on this matter. I get it.
The railway I use to travel cancelled a train the other day. They couldn't find an engineer to drive it. Losing a train? Eh, that's peanuts for them.
Actually, they done fucked up the whole company. Fired a bunch of engineers to keep the fat manager wallets fat. Now they need more engineers and can't find any
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Staying on topic is a barrier to lolz.
So is @PJH bringing reality into an argument. Cheeky bastard.
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A while ago, I woke up in a weird position and my body thought my arm was in a different place than it actually was. I could feel my elbow stopping movement when my arm felt like it was at a 100 gradian angle and I was able to do what felt like moving my lower arm past my shoulder and back the other way. I turned on the light and my brain figured out where my arm actually was.
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A while ago, I woke up in a weird position and my body thought my arm was in a different place than it actually was. I could feel my elbow stopping movement when my arm felt like it was at a 100 gradian angle and I was able to do what felt like moving my lower arm past my shoulder and back the other way. I turned on the light and my brain figured out where my arm actually was.
What.
The.
Fuck?
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Don't you ever use human units?
I am telling you, he is a freaking elaborate Turing test and we have all failed.
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But I break any combination of Three Laws daily!
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It would be a bit ironic1 for me to chastise Ben for posting something off-topic, but at least my derailment ( ) was relevant to the discussion of trains. Ben's?
1 Now we can derail the topic into a discussion of whether that is a valid use of the word "irony."
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But I break any combination of Three Laws daily!
Well...fuck. He is not programmed with the 3 laws. We. Are. Screwed.
Pray he has no apendages and is merely some code running on a VPS somewhere, playing DF all day long.
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Now we can derail the topic into a discussion of whether that is a valid use of the word "irony."
Let's ask Alanis Morrisette. She should know.
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Fuck irony!
Of course, I'm being sarcastic here.
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Staying on topic is a barrier to lolz.
I'm just ruffled because I KNEW if I didn't mention derails, some joker would come along and do it for me. At least you were did my bidding, so I guess there's that.
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100 gradian angle
If you're going to use silly measurements, you should pick truly silly ones.
Oh, wait, you did. Carry on.
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INB4 joke about derailing the topic.