Green Line real-time data and tracking

[StefanW]

(Since the other thread was primarily about the count-down signs which aren't active on the Green Line today, I thought I'd start a new topic.)

Apparently above-ground Green Line tracking will go live this afternoon!

http://bostinno.streetwise.co/2014/10/2 ... real-time/" onclick="window.open(this.href);return false;

That's an unexpected surprise! Underground tracking is still scheduled for next year though.

Indeed it's live!

Check out my newest app, for Subway Live Tracking - including the above-ground Green Line!

http://sites.harvard.edu/~wuensch/T/subway-map.html

[Arlington]

Hooray for the march of open information!

[StefanW]

The Green Line Central Subway now appears to be fully covered by the newest phase of MBTA live tracking. The MBTA hasn't made an official announcement about it yet, but I thought I'd mention it here since the data don't lie.

Example from my app:

Green Line Central Subway.png

http://sites.harvard.edu/~wuensch/T/subway-map.html" onclick="window.open(this.href);return false;

[Arlington]

The Green Line Central Subway now appears to be fully covered by the newest phase of MBTA live tracking. The MBTA hasn't made an official announcement about it yet, but I thought I'd mention it here since the data don't lie.

Yippee!

[Gerry6309]

The Green Line Central Subway now appears to be fully covered by the newest phase of MBTA live tracking. The MBTA hasn't made an official announcement about it yet, but I thought I'd mention it here since the data don't lie.

Yippee!

All of the lines seem to have some digital black-holes, especially when trains are at terminals, awaiting departure. There are also occasional phantom trains which don't show up at all.

From that, I assume that a reverse key has to be in forward for the lead car to show up.

[diburning]

A few trains have passed me at park street. None of them showed up on the tracker. I bet not every car is set up yet.

[StefanW]

A few trains have passed me at park street. None of them showed up on the tracker. I bet not every car is set up yet.

It is correct that not every car will register, but every train is supposed to show up - with the lead car displayed. The MBTA data operations people explained how it's supposed to work...
- above ground the GPS unit in each Type 8 will send its position, and the AVI site at the trip origin will kick off the train as being "known" for that trip.
- underground the signal blocks indicate car / train location, and the AVI sites (which are more numerous underground) will handle the ID.

Note that (according to the MBTA) all Type 8 cars have the GPS units installed, but only some Type 7s have GPS installed. Since almost all trips have at least one Type 8 in the train, it's believed that 99% of revenue trips will be tracked above-ground.

To handle underground, a significant number of brand new AVI sites have been installed. According to the MBTA, as of last month there were only two remaining AVI sites that were not finished being installed. However, I have not heard whether there is now an AVI site for every signal block. I would bet probably not, since they are really only needed where there are converging / diverging routes. The signal blocks ought to handle the tracking in-between AVI sites.

The MBTA people also said that Park St. is the single most difficult area to deal with tracking the trains. It's because of the wall / fence westbound split, plus the loop. Seeing as the official MBTA announcement about the Central Subway live tracking data hasn't happened yet, I'm guessing they are working out some final issues in the area around Park St.

[StefanW]

A few trains have passed me at park street. None of them showed up on the tracker. I bet not every car is set up yet.

I think I know what might have happened. It seems like the artificial "GPS" position data that the MBTA applies to each underground signal block is not very granular. In other words... many Green Line trains are showing up on my map view right on top of each other because they are getting the same exact "GPS" position applied and sent. This seems to be happening most noticeably at Park because each platform track can have multiple trains. I'm also not sure if the T is sending different positions for each of the four tracks.

I was at Park St. about 25 min. ago and all three eastbound trains had live tracking. (A two-car on track 3 loop headed by Type 7, two-car on track 4 out of service headed by Type 7, and a Lechmere train on track 4 headed by a Type 8.) All three of those were on my map, but the icons were all in exactly the same spot so it was almost impossible to tell!

I think I know a way I can tweak my map view to account for multiple train icons in the same spot. I don't want to play with the raw position data but I think I can come up with a way to prevent totally overlapping icons.

Keep the feedback coming!!! The more specific you all can be about what you see (or don't see) will help me make app improvements. Thanks!

[StefanW]

Also - try clicking on the "Show a detailed table" button below the map, then sort the table on the "Lead Car No." column by clicking on the column heading. That way you can search by car number if you're trying to find something specific. Obviously that doesn't help if you're browsing for trains by location, but at least you can find out if the train you're looking at is being tracked or not.

[StefanW]

It seems like the artificial "GPS" position data that the MBTA applies to each underground signal block is not very granular. In other words... many Green Line trains are showing up on my map view right on top of each other because they are getting the same exact "GPS" position applied and sent. This seems to be happening most noticeably at Park because each platform track can have multiple trains. I'm also not sure if the T is sending different positions for each of the four tracks.

Correction: I've figured out that the MBTA's live tracking isn't online yet between Arlington and Park Street. I've observed eastbound trains "piling up" at Arlington, and westbound trains "piling up" just before Park Street. In both cases the trains will jump across that route section and appear with live position data on the other side. This tells me that the AVI sites and/or tie-in to the signal blocks isn't quite done yet.

[ns3010]

Countdowns at Kenmore went live this morning. Arrival times for the surface sections B and C (along with D) are also available on at least a few apps I have tried. Nothing new for the E or rest of the central subway.

[StefanW]

Countdowns at Kenmore went live this morning. Arrival times for the surface sections B and C (along with D) are also available on at least a few apps I have tried. Nothing new for the E or rest of the central subway.

According to the MBTA, real-time predictions are now available for Hynes. I agree, because they are showing up in the data.

They actually said "at Hynes" which makes me think the countdown signs in the station are also active. Anyone seen them yet?

[ns3010]

Countdowns at Kenmore went live this morning. Arrival times for the surface sections B and C (along with D) are also available on at least a few apps I have tried. Nothing new for the E or rest of the central subway.

According to the MBTA, real-time predictions are now available for Hynes. I agree, because they are showing up in the data.

They actually said "at Hynes" which makes me think the countdown signs in the station are also active. Anyone seen them yet?

They are indeed: https://twitter.com/MBTA/status/634380928060665857

[Adams_Umass_Boston]

Following up with a yes, they even announce the "next train to Park is now arriving" No approaching announcements though.

Its my daily station.

[The EGE]

Much of the Central Subway is going live this week. Arlington and Copley both directions today; Boylston and Park eastbound tomorrow; Haymarket, NS, and Science Park eastbound on Thursday.