Train doors require GPS signal to open despite stations being underground (2014) • Hacker News Board

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

#51

Post by tjoff » Sat, Mar 14, 2015, 4:57 PM UTC

mikeash wrote: post #11

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.

Somebody decided that GPS was a good idea here, and didn't think about problems underground. Silly, but understandable. Somebody else decided that having doors controlled by location was a good idea here, and didn't think somebody would specify a system that doesn't work at some stations. At some point during procurement and installation of the equipment you'd think somebody would have raised a red flag. Unless, of c…

The GPS solution should have been shot down on sight - regardless of where in the process it was made up.

The only sensible reason for this is that someone responsible had a friend that sold GPS-beacons.

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

#52

Post by mike_hearn » Sat, Mar 14, 2015, 5:05 PM UTC

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.

Only on underground stations. Possibly most of the stations this class of train stops at are above ground, and it made sense there to avoid big station upgrade works. Just one little GPS receiver on the train instead. You can see how it could happen.

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

#53

Post by mike_hearn » Sat, Mar 14, 2015, 5:06 PM UTC

pilif wrote: post #32

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 f…

I'm not sure if that's impressive, or if I should be scared that trains randomly reboot their engines whilst in motion and nobody seems to care or investigate?! What kind of issue can be resolved by rebooting an engine, exactly?

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

#54

Post by rcthompson » Sat, Mar 14, 2015, 5:08 PM UTC

mikeash wrote: post #11

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.

Somebody decided that GPS was a good idea here, and didn't think about problems underground. Silly, but understandable. Somebody else decided that having doors controlled by location was a good idea here, and didn't think somebody would specify a system that doesn't work at some stations. At some point during procurement and installation of the equipment you'd think somebody would have raised a red flag. Unless, of c…

I don't think the choice of GPS for a train system is understandable at all.

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

#55

Post by superuser2 » Sat, Mar 14, 2015, 5:19 PM UTC

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

http://en.wikipedia.org/wiki/Selective_door_operation

The real, less trivial problem is only opening the doors of train cars that actually fit on the platform.

GPS was just a poor choice of positioning system. There are already widely deployed systems where what is essentially an RFID tag sits at a fixed point on the track between the rails and, when scanned, tells the train exactly where it is.

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

#56

Post by vidarh » Sat, Mar 14, 2015, 5:20 PM UTC

pbowyer wrote: post #45

bagels wrote: post #42

Earlier quoted context omitted.

There is no mention of cattle or cows in that story?

British slang for passengers - "The train operating companies treat us like cattle". Actually, cattle may get treated better...

You'd risk being arrested if you treated cattle the way passengers are treated on some British commuter routes.

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

#57

Post by TazeTSchnitzel » Sat, Mar 14, 2015, 5:24 PM UTC

I can't believe HN is reacting to this as if checking location is a bad idea. It does have an emergency override.

On the underground, particularly during rush hour, doors opening on the wrong side, or in the wrong place, could cause people to fall out of the train onto the tracks, in the dark, and risk serious injury or even death (especially with electrified rails).

And using GPS and repeaters in the few spots where the signal's poor sounds like a practical and cost-effective approach. Given the issues, perhaps they should've implemented it some other way, but it's hardly the ridiculous solution you're all making it out to be.

As superuser2 mentions below, there's even a non-safety reason for this feature: long trains in short stations. https://news.ycombinator.com/item?id=9203351

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

#58

Post by TazeTSchnitzel » Sat, Mar 14, 2015, 5:33 PM UTC

chez17 wrote: post #47

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

Of course not. This was some government contractor taking the tax payers for a ride. They could charge $x more per train this way and just through in a shitty gps device. Things like this aren't accidents.

Surely you mean £x more. And you're wrong anyway, this is a standard feature to allow long trains to enter short stations.

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

#59

Post by TazeTSchnitzel » Sat, Mar 14, 2015, 5:34 PM UTC

Shivetya wrote: post #20

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

surely there are restrictions opening while moving but while stopped seems a bit odd. Aren't they paying the driver to think, to know when to open or not open doors?

Reducing the amount the driver has to think reduces the potential for human error.

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

#60

Post by fche » Sat, Mar 14, 2015, 5:39 PM UTC

TazeTSchnitzel wrote: post #57

I can't believe HN is reacting to this as if checking location is a bad idea. It does have an emergency override. On the underground, particularly during rush hour, doors opening on the wrong side, or in the wrong place, could cause people to fall out of the train onto the tracks, in the dark, and risk serious injury or even death (especially with electrified rails). And using GPS and repeaters in the few spots where…

Use of broadcast signals like GPS for safety-critical purposes makes them a target for adverse interference - like a jammer hoping to mess with / trap people on the train.