Berlin public transport in real time • Hacker News Board

Re: Berlin public transport in real time

#101

Post by peterjmag » Thu, Nov 19, 2015, 2:15 PM UTC

DangerousPie wrote: post #56

Looks like they are just interpolating the location between two stations using the expected arrival times. If no expected arrival times are available, they simply simulate the location to match the planned arrival times. So this is not really "live". > VBB-Livekarte zeigt berechnete Positionen der Fahrzeuge zwischen zwei Stationen; falls kein Live-Fahrplan vorhanden, dann Position gemäß geplanten Fahrzeiten

Good catch. I live in Berlin and use this sometimes, and I hadn't actually noticed that disclaimer before. (For future reference, it's under "Position der Fahrten" on [1].)

Munich's live S-Bahn map[1] takes a slightly different approach:

Um die Position der S-Bahnen auf der Karte anzuzeigen, werden die Positionsmeldungen der Züge an ausgewählten Signalstandorten erfasst und dazwischen hochgerechnet. Es handelt sich somit derzeit um keine GPS-Ortung.

(from "So funktioniert's" on [2])

So they don't actually use GPS positioning either, but they do interpolate from data that comes from their rail signalling system, which I imagine is a bit more precise than using realtime departures and arrivals in hh:mm.

[1] http://www.vbb.de/de/article/fahrplanauskunft/vbb-livekarte/...

[2] http://s-bahn-muenchen.hafas.de/bin/540/help.exe/dn?tpl=live...

[3] http://www.s-bahn-muenchen.de/s_muenchen/view/fahrplan/echtz...

Re: Berlin public transport in real time

#102

Post by Piskvorrr » Thu, Nov 19, 2015, 2:17 PM UTC

Zach_the_Lizard wrote: post #98

Piskvorrr wrote: post #52

Earlier quoted context omitted.

Not really. As far as I understand the technologies (and I assume that Berlin does the same thing as every other city-user), a precise ("physical") GPS position is usually not reported (although newer systems do that as well), but a position at a "logical" map is. In case of buses, this usually means "left the previous stop at $xx:$yy, with $zz seconds of delay; reported average speed is normal for this area, so expe…

My understanding is that with newer CBTC signalling systems--not sure if Berlin is using that--the trains know pretty much exactly where they are on the track, along with the positions of all other trains, speeds, braking distance, etc. This allows the trains to run closer together than they could using fixed block signalling technology. It's not required for full automation, but it makes full automation relatively s…

Oh, sure, there's all sorts of useful telemetry coming from the trains and the tracks, even with fixed-block signalling (unless you have a 100-year-old signalling infrastructure ;)). That's pretty much the case of most modern train systems: the driver is there essentially to (re)boot the train computers, push the "doors close" button, and for emergencies. Apart from that, the trains pretty much drive themselves (except when they don't, oh the joys of software).

However, even when the position of the train is known precisely (no need for fancy CTBC, just start counting wheel revolutions from a known starting point and reset any measuring error at the next known-good point, usually a station - which is the basic way the Parisians do it with their driverless metro lines), not every transport agency exposes this sort of raw data to the general public; usually it's watered down to "it's between Station A and Station B, with X seconds of delay."

Re: Berlin public transport in real time

#103

Post by ojii » Thu, Nov 19, 2015, 2:25 PM UTC

Japan: http://www.demap.info/tetsudonow/

Re: Berlin public transport in real time

#104

Post by james_pm » Thu, Nov 19, 2015, 2:44 PM UTC

And Toronto's bus and streetcar network...not quite as fancy, but Toronto's Open Data system makes this possible.

Live tracking: http://totransit.ca

Open Data: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=9e56...

Re: Berlin public transport in real time

#105

Post by ehosca » Thu, Nov 19, 2015, 2:56 PM UTC

why can't NYCT/MTA have something like this?

Re: Berlin public transport in real time

#106

Post by djtriptych » Thu, Nov 19, 2015, 2:58 PM UTC

ehosca wrote: post #105

why can't NYCT/MTA have something like this?

That was my first question too. If they ever published live train positions I'd build something like this immediately.

Re: Berlin public transport in real time

#107

Post by gsnedders » Thu, Nov 19, 2015, 3:01 PM UTC

Zach_the_Lizard wrote: post #98

Piskvorrr wrote: post #52

Earlier quoted context omitted.

Not really. As far as I understand the technologies (and I assume that Berlin does the same thing as every other city-user), a precise ("physical") GPS position is usually not reported (although newer systems do that as well), but a position at a "logical" map is. In case of buses, this usually means "left the previous stop at $xx:$yy, with $zz seconds of delay; reported average speed is normal for this area, so expe…

My understanding is that with newer CBTC signalling systems--not sure if Berlin is using that--the trains know pretty much exactly where they are on the track, along with the positions of all other trains, speeds, braking distance, etc. This allows the trains to run closer together than they could using fixed block signalling technology. It's not required for full automation, but it makes full automation relatively s…

As far as I'm aware, all the Berlin S-Bahn and U-Bahn lines use absolute block signalling.

FWIW, automation is actually mostly tangential to absolute v. moving block signalling. As far as I'm aware, most automated systems still use absolute block signalling.

Re: Berlin public transport in real time

#108

Post by callesgg » Thu, Nov 19, 2015, 3:09 PM UTC

pb4 wrote: post #58

dearmrpres wrote: post #53

There is a similar tool for the whole world created by a german student a few years ago - http://tracker.geops.de - albeit without RT data for berlin because apparently they dont have access to it. But they do have RT data for the netherlands.

Creator here - since 2014, development is being done at geOps where I am currently working at. geOps is also providing the entire infrastructure. We are constantly looking for more static or real time feeds. We are using the same method as the VBB - interpolated timetable data augmented with station-based delay-information where available.

Wow that is very cool, not super accurate where i live but cool.

BTW the map cant handle unicode stuff properly there is a boat line called "Sjövägen" where is live and on the map it is named "Sj?"

Re: Berlin public transport in real time

#109

Post by kokey » Thu, Nov 19, 2015, 3:09 PM UTC

DangerousPie wrote: post #56

Looks like they are just interpolating the location between two stations using the expected arrival times. If no expected arrival times are available, they simply simulate the location to match the planned arrival times. So this is not really "live". > VBB-Livekarte zeigt berechnete Positionen der Fahrzeuge zwischen zwei Stationen; falls kein Live-Fahrplan vorhanden, dann Position gemäß geplanten Fahrzeiten

That shouldn't be a problem if the trains are on time.

Re: Berlin public transport in real time

#110

Post by brianzelip » Thu, Nov 19, 2015, 3:15 PM UTC

Amtrak (USA) has a static visualization of its active trains.

Unfortunately you can't click to it, so here's a screenshot: http://imgur.com/TJwTBAY

To get to it, go to http://www.amtrak.com/find-train-bus-stations-train-routes

then click on the "Check Train Status" image near the top right of the page.

The difference in train presence between USA and elsewhere is staggering (and embarrassing).