CBTC - General Discussion

[Eric B]

Just started qualification today. (Also, didn't know it was actually running on QBL, on the midnights, so E and F and even some M TO's, are qualifying already!)

[Emil]

On 11/16/2020 at 3:53 AM, Vulturious said:

Aren't they still working on QBL CBTC? Regardless, 8th Av is going to need the R211s to arrive before they can start on construction since there isn't enough to really run CBTC and it would basically be useless.

oh yes true true, they're still on that. plus with the delay of the R211s I for sure know for a fact they won't start yet.

[RestrictOnTheHanger]

Is any portion of the QBL CBTC in revenue service? I haven't ridden since August. 

Edit: just saw Eric B's comment , still curious as to where and when its active

Edited November 20, 2020 by RestrictOnTheHanger

[Eric B]

It's running on the midnights, where it's not revenue now.  It's on the express tracks from Roosevelt to Kew Gardens, and the local tracks from Continental to Kew Gardens (I guess so the could still have it past Continental).

(Just finished qualification today!)

[MarkGuy]

On 11/20/2020 at 10:59 PM, Eric B said:

It's running on the midnights, where it's not revenue now.  It's on the express tracks from Roosevelt to Kew Gardens, and the local tracks from Continental to Kew Gardens (I guess so the could still have it past Continental).

(Just finished qualification today!)

Well now, it's during rush hours as well. But only in ATPM. Not looking forward to it, as I'm not personally a fan of operating in CBTC. 

[QM1to6Ave]

17 hours ago, MarkGuy said:

Well now, it's during rush hours as well. But only in ATPM. Not looking forward to it, as I'm not personally a fan of operating in CBTC. 

What's ATPM?

[MarkGuy]

10 minutes ago, QM1to6Ave said:

What's ATPM?

Not going to go into heavy detail hete but to simplify, its one of the operating modes in cbtc.

[QM1to6Ave]

22 minutes ago, MarkGuy said:

Not going to go into heavy detail hete but to simplify, its one of the operating modes in cbtc.

Thanks! I figured CBTC sounds simple when the MTA describes it, but there must be a lot of complexity to it

[RedLine]

ATPM regulates the speed of the train but allows for manual or automatic operation in CBTC area.

[MHV9218]

Well, I'll go into it in some detail since this is all public information via the suppliers. You have three fundamental functions of CBTC:

Automatic Train Protection (ATP): speed regulation and collision fail-safes, hazard avoidance

Automatic Train Operation (ATO): automatic station stops, all features of ATP + door control

Automatic Train Supervision (ATS): systemwide train management

ATO is the general goal for operations within the system. ATP is the first step on the way. A subset of ATP is ATPM or Automatic Train Protection – Manual. In APTM, a T/O controls brakes and propulsion, but speed and direction are regulated by the computer (the VC - Vehicle Controller). It's an in-between function of CBTC that I would assume is being tested along the QBL before full ATO takes over.

ATP helps in that it provides limited protection even to non-CBTC enabled fleets on the same trackways, though the TA doesn't really mix stock once a fleet is converted. 

CBTC's ATPM mode is essentially a version of what the Feds describe as Positive Train Control. PTC for the railroads means cab signaling and speed/hazard regulation, which is what ATP achieves. A variety of different contractors offer a version of this system.

[Eric B]

ATP basically corresponds to what they used to call "cab signaling", where your r/y/g is on a screen, in a round dial, with your speed shown via the actual dial, and you have to try to keep it in the green. It's actually more work than WSP (the conventional signal system), because you have to pay attention to this screen in addition to the roadway. When I'm seeing is that the policy is to just turn the ATO off regularly on the outdoor portions of the line (which on the (7) is almost the entire line!) due to the work gangs, and those tend to be the hardest areas for manual operation, because of the grades and curves, with sudden speed limit drops.

(Another term I had never heard until qualifying is "Movement Authority Limit", which is basically what was known as the "moving block" —as opposed to the old "fixed block", for the area ahead that CBTC control has been granted to each train approaching. That's when you see the signals start to flash green.

[Ethan777]

I'm from Singapore and our 2 oldest lines have been running on Thales SelTrac CBTC for 2 years since. However, our system is a GOA3 version. Our Train Captains are totally handsfree in Automatic Mode (AM) and only intervene when necesssary. A daily shift right now is mostly to monitor their train and watch the tracks ahead.

For your IRT Flushing Line, do you guys also have the ATS wet rail command feature available in your iteration of Thales CBTC?

Its a ATS Operator command from OCC where you can apply it to a platform and the brake rates of controlled trains will either be reduced by 25% (Type I) or 50% (Type II) when arriving into platform - dependent on how severe the wet tracks are.

In Singapore, we administer Type I or II based on weather forecast - how light/heavy the rain is.

I also read in earlier pages of forums that your dwell time is rather padded even under CBTC and this is affecting headway. Over in Singapore we are adopting similar practice by adding a couple of seconds per elevated station stop to cater to this wet rail profile - just in case sometime in the day, we need to apply it. But I understand we recently removed it for one of the lines in a recent timetable change.

So far, Thales on our end has stabilised very well, quite unlike initial months. We are pulling off 110s headway (32tph) for 1 of our lines during peak hours for ard 30mins - our dwells are quite long too (~40-50s) - comparable to what I saw on a string-line graph in earlier posts.

But we are actually handling quite fine despite the long dwell time. Trains still can be punctual.

 

Edited December 27, 2020 by Ethan777

[RTOMan]

ATO wont be used for some time im told..

The CBTC limit area is only from Kew Gardens to Roosevelt ave all four tracks.

There are certain "kinks" that need to be worked out..

Only 6 trains on the F line have CBTC enabled the Dispt will inform the Crew.

If a TO isn't qualified the train stays in Bypass.

The thing that Kicks rocks is the work zones..

Instead of it clearing once the front of the train clears the resume it clears when the back of the train does..

I went through three of em from Roosevelt to Kew gardens on my last half.. Felt like my hand was gonna fall off lol..

[MHV9218]

4 hours ago, RTOMan said:

Instead of it clearing once the front of the train clears the resume it clears when the back of the train does..

I went through three of em from Roosevelt to Kew gardens on my last half.. Felt like my hand was gonna fall off lol..

Lmao! That sounds like the MTA... With stuff like this TPH is always gonna be nowhere near what the system is capable of. It's stuff like this and perpetual flagging that's part of why the  ATO has been such a shitshow. I mean, I get it, ATP is better than nothing, certainly the feds just want PTC everywhere and this achieves that, but I mean, not much. NJT had ATC and speed monitoring in cabs since what, like 2008? I'll never get that beeping out of my head...

Sometimes it feels like we're barely that far out from Identra coils, which were introduced on the Flushing, oh, I don't know, sixty years ago?

[Eric B]

12 hours ago, RTOMan said:

ATO wont be used for some time im told..

The CBTC limit area is only from Kew Gardens to Roosevelt ave all four tracks.

There are certain "kinks" that need to be worked out..

Only 6 trains on the F line have CBTC enabled the Dispt will inform the Crew.

If a TO isn't qualified the train stays in Bypass.

The thing that Kicks rocks is the work zones..

Instead of it clearing once the front of the train clears the resume it clears when the back of the train does..

I went through three of em from Roosevelt to Kew gardens on my last half.. Felt like my hand was gonna fall off lol..

That's nothing; these days on Canarsei, some "glitch" they say is causing the work zones around Livonia to stretch for two or three stations! And this has been going on for weeks now! They should just turn the CBTC off for that whole stretch and go WSP; except that there is a gap in the signals around New Lots (especially southbound) for some reason (but otherwise, they're spaced normally, for all the unequipped trains going to the wash, or storage such as the R32 there). But in the midday, having such along "absolute block" under WSP would be better than what they're doing now.

[Infamous85]

Is the entire QBL being outfitted with CBTC? The map I’ve seen only shows part of the line.

[Lex]

50 minutes ago, Infamous85 said:

Is the entire QBL being outfitted with CBTC? The map I’ve seen only shows part of the line.

It's a phased project. At present, only part of it has CBTC, but the plan is for the entire thing to receive it.

[MarkGuy]

On 12/26/2020 at 12:37 AM, Eric B said:

ATP basically corresponds to what they used to call "cab signaling", where your r/y/g is on a screen, in a round dial, with your speed shown via the actual dial, and you have to try to keep it in the green. It's actually more work than WSP (the conventional signal system), because you have to pay attention to this screen in addition to the roadway. When I'm seeing is that the policy is to just turn the ATO off regularly on the outdoor portions of the line (which on the is almost the entire line!) due to the work gangs, and those tend to be the hardest areas for manual operation, because of the grades and curves, with sudden speed limit drops.

(Another term I had never heard until qualifying is "Movement Authority Limit", which is basically what was known as the "moving block" —as opposed to the old "fixed block", for the area ahead that CBTC control has been granted to each train approaching. That's when you see the signals start to flash green.

Essentially what is being said here. In  CBTC, your train essentially becomes a "smart" train. It communicates with transponder devices on the road bed. This accomplishes two things:

Allows the train to discover what direction it is going in. And two, its location. This is a process called "localization." Once this process is successful, the train then communicates its location to what are known as "zone controllers," along the line. These controllers then tell the train all the obstacles ahead of it, including signals, other trains and the like. This is just an extremely basic summary on my end.

In ATPM, the train operator does operate, but the train itself sets the speed limits of how fast you can go in particular areas. If it determines you are going too fast in an area, it sends you a warning display and sound through the dial interface mentioned by Eric. Keep ignoring it, and the sounds progress, and the train eventually applies service braking. Ignore it too long, and the train dumps.

I do not enjoy operating in this mode because the train will set a certain speed restriction for you through an area, but in ATO (when the train operates), it will blast through said area much faster.

MAL also allows a much closer operating profile for trains, allowing preceding trains to come within 25 feet of the one in front. That's why in CBTC, you can see trains pull into the station, one after the other, in such rapid fashion.

 

[MHV9218]

Although isn't one of the NYCT-specific hangups of CBTC that trains can only enter a station once the entire train in front of it has cleared the platform? My understanding is that the system is perfectly happy for a train to follow 25ft behind a departing train, but RTO made sure the system is programmed not to broach the platform at the same time (which is probably a relic of some of very old rule books).

[Lawrence St]

1 hour ago, MarkGuy said:

Essentially what is being said here. In  CBTC, your train essentially becomes a "smart" train. It communicates with transponder devices on the road bed. This accomplishes two things:

Allows the train to discover what direction it is going in. And two, its location. This is a process called "localization." Once this process is successful, the train then communicates its location to what are known as "zone controllers," along the line. These controllers then tell the train all the obstacles ahead of it, including signals, other trains and the like. This is just an extremely basic summary on my end.

In ATPM, the train operator does operate, but the train itself sets the speed limits of how fast you can go in particular areas. If it determines you are going too fast in an area, it sends you a warning display and sound through the dial interface mentioned by Eric. Keep ignoring it, and the sounds progress, and the train eventually applies service braking. Ignore it too long, and the train dumps.

I do not enjoy operating in this mode because the train will set a certain speed restriction for you through an area, but in ATO (when the train operates), it will blast through said area much faster.

MAL also allows a much closer operating profile for trains, allowing preceding trains to come within 25 feet of the one in front. That's why in CBTC, you can see trains pull into the station, one after the other, in such rapid fashion.

 

So how come whenever a single signal fails on Carnarsie, it brings down the entire signal network on the line?

[Ethan777]

1 hour ago, MHV9218 said:

Although isn't one of the NYCT-specific hangups of CBTC that trains can only enter a station once the entire train in front of it has cleared the platform? My understanding is that the system is perfectly happy for a train to follow 25ft behind a departing train, but RTO made sure the system is programmed not to broach the platform at the same time (which is probably a relic of some of very old rule books).

This idea of not broaching platform is an inherent cbtc behaviour within Product. Its not NYCT specific 

 

This is an ATS feature that is enforced thru ZC not issuing LMA until it knows front train has cleared platform track circuit. 

 

 

 

 

[Lex]

4 hours ago, Lawrence St said:

So how come whenever a single signal fails on Carnarsie, it brings down the entire signal network on the line?

I suspect that you're thinking of AWS, which consists of large fixed blocks. The failsafe that kicks in whenever a signal fails in a traditional fixed-block setup would be expected to do so in case of AWS failure. There'd be no reason for CBTC to not collect any information regarding it.

[RTOMan]

On 12/29/2020 at 8:49 PM, Lawrence St said:

So how come whenever a single signal fails on Carnarsie, it brings down the entire signal network on the line?

If there is a signal problem (depending if its past Bway Junction or not) depends on how the system is.

There procedures to do when keying by a signal when in CBTC Mode.

Put it this way the more signals the easier it is.

Now a CBTC failure is basically no movement past bway Junction not enough signal protection.

[Lawrence St]

6 hours ago, RTOMan said:

If there is a signal problem (depending if its past Bway Junction or not) depends on how the system is.

There procedures to do when keying by a signal when in CBTC Mode.

Put it this way the more signals the easier it is.

Now a CBTC failure is basically no movement past bway Junction not enough signal protection.

Past Bway Jct in which directions? Towards Rockaway or Towards 8th Av?

[RR503]

1 hour ago, Lawrence St said:

Past Bway Jct in which directions? Towards Rockaway or Towards 8th Av?

Towards Canarsie has dense AWS to support non-equipped mvmts to and from the wash at Canarsie Yard. Towards 8th Avenue has AWS, but the AWS there is low qual -- during Canarise Tube work, a work train north of BWJ => 20 min headway.

(Just to be clear, I do not endorse more AWS. Less AWS is actually better for CBTC reliability and lifetime maintenance costs; we should just equip our work trains)

Edited December 31, 2020 by RR503