Tuesday, June 18 Learning about CBTC

[soid]

 I got up by 8:15 and went to the office. I was excited to chat with Abhi and Kenny; when did I see them last time? Last Tuesday? Or Thursday? A long time ago. I got to the office and found out that both of them were working from home. Oh, well, I hung out by myself.

I started searching various keywords in Confluence from yesterday's meeting: ATS, PLC-A, PA/CIS, CBTC, etc. That's a rabbit hole, of curse. I skimmed a manual for train operators and similar documents. As I understood ATS-A is what people call internally CBTC – a train control system developed by Siemens. It includes equipment on the train (on-board), equipment in the tunnel (wayside), various servers gathering the signals from both, a control center operated by dispatchers, and various automatic systems like automatic train stop to prevent collisions. PA/CIS are the monochromic arrival displays on the A division stations. Those displays are hooked directly into Siemens' control system via separate network, and somehow it's hard for us to get access to that information. And then all that can be complicated by different systems used on different lines. ATS feed has sub-second latency and goes to some other old subsystem that provides public GTFS-rt feed used by Google Maps and other companies – that feed in turn has 20+ seconds latency. Plus it's a pull based feed. In general mood, the feeling about this Google's GTFS-rt format is not very positive.

So, my next project is to tap into that low latency ATS-A feed and try to re-create the system state for better quality data in our app (better than GTFS-rt). I say we should fix GTFS-rt so everyone benefits, but that might be too heavy a project for now. We will see. And then comes another strange requirement from Sunny: we actually don't want to be inconsistent with PA/CIS displays; that may cause too much confusion even if we predict better arrival times. This curbs my ambition of making seconds precise arrival times; you know, like in Europe, they have those countdown clocks counting seconds: 15, 14, 13, .. and you see the train arriving. In New York, we say arriving in 1 minute, and then "Arriving". I will see.

At home, I checked the mouse traps that I installed in the morning with cheese on them. All day I was afraid of finding my friendly mouse smashed by one of these traps: with blood, the mouse perhaps still alive, you know. I was amazed to find the traps empty without the cheese. I put another cheese, then looked at the traps more carefully, and realized I had to put the cheese on a hook; I did so. I found the cheese gone in two hours. Amazing. Either this mouse is smart, or my traps are no good. I put some more cheese for the night.

Comments

[juan_gandhi]

I love this kind of projects and challenges.

[ionial]

Real legacy systems!
I believe, only city pipes and sewer are more legacy than this

[soid]

Oh no, those are the most modern systems that are here to stay for decades. But it's only deployed on the A division (roughly, half of the lines). Siemens CBTC is also deployed in Paris, and Hong Kong, and other metropolises.

The real legacy is on the G train – a 90 years old signal system that will hopefully be replaced this summer:
https://gothamist.com/news/mta-says-full-length-g-trains-could-be-possible-1-day-thanks-to-lines-summer-shutdown