QBL CBTC: I need an explanation...

[RR503]

1 hour ago, Deucey said:

So in effect, all CBTC is doing is spending a large amount of money to do what  did before  took control?

That’s a complex question.

In theory, CBTC is incontrovertibly a more capable system than fixed blocks. People are absolutely right in saying that it should be installed — not only would it theoretically increase capacity, but it, if installed without all the bells and whistles, could dramatically cut maintenance costs. 

But that, of course, glosses over a whole bunch of things. Really, the issue is twofold.

First, the thing restricting NYC subway capacity/reliability today isn’t the signal system, per se, but instead the way said system is operated. We used to operate 36tph on the  with fixed blocks, 34tph on CPW express, 31tph on Broadway express. The dramatic reductions in capacity seen on those corridors aren’t a result of some inherent flaws in yesterday’s signals, but instead ones in today’s poor service planning, a rash of inefficiency-causing signal mods, an illogical, fear-based operational culture, and the realities of the infrastructure itself. Those issues all carry over into CBTC — albeit with more cushioning given the aforementioned inherent capability of the new system. This is to say that if you wanted to extract more capacity/reliability from the system, you’re much better off starting by reviewing/adjusting operations under the current system — it’s cheaper and faster, and it creates a more capable operating environment in which a subsequent CBTC installation can reach its full potential. 

Second, there is the issue of cost. Byford projects $40 billion over the next 10 years to pay for this. There’s absolutely something to be said for “better to spend now than later; we’ll fix ops as we go along” but that neglects the zillion ways in which NYC CBTC installs synthesize modern tech and the Stone Age.

On the most basic level, we only have two companies qualified to provide CBTC equipment, meaning that bids are sure to be inflated. Then, there’s the issue of overconsulting. This is a general issue with MTA capital projects, but the amount spent on “independent analyses” needs to come down — not only for the sake of our wallets, but also for the sake of the contractors, as having 12,000 different entities telling you what to do can’t be easy. Wonkiness in outage planning has been addressed with the concept of consistent night/weekend closures, but there remains the need to coordinate within the agency’s various departments to make sure the necessary equipment is in place at the right time (this can be a big struggle) and to assure that departments involved in the project itself are all on the same page. And then we hit the system itself. I’ve long been an advocate for minimizing the use of auxiliary wayside signals (keeping basic function at interlockings isn’t a bad idea, but elsewhere...) but the agency’s policy seems to have been moving in the opposite direction. What we do today is take out all the old block signals, put in a spanking new block system capable of sustaining full service, add CBTC...and then (as I recently learned) we remove block signals until we have signal spacing capable of just 12tph. Talk about wasteful. I’m not a technical expert, so please take the following (and honestly any part of this post you find suspect) with some salt, but beyond the areas around interlockings where the whole relay system has to be replaced before CBTC for compatibility, we’re really just spending a crapton of money for nothing — especially given that 5 min headway capability won’t do jack shit for service during a disruption; you’ll just get congestion (unless you’re on the  or in the Rockaways). I emphasize these auxiliary signals so much, by the way, because their installation actually accounts for a disproportionate amount of CBTC related service changes. If you weren’t adding them, you’d be overlaying some transponders and relay cabinets on existing track — that’s a good bit of work, yes, but nothing compared to the task of cutting in new block signals with different control lines, track circuits, wiring, logic, etc.  

Point being, there are a ton of changes that could be made to make CBTC cheaper before we go all out on it. Methinks we make those before we go in — just as we measure twice before we cut. 

 

Edited October 16, 2018 by RR503

[Union Tpke]

@RR503 I know that there are rooms on platforms and the shorter platforms on Culver that would make it hard to justify, but I would love to see the report that resulted from this: http://www.nydailynews.com/new-york/nyc-transit-tests-11-car-train-means-alleviating-f-line-overcrowding-article-1.361516

https://www.brooklynpaper.com/stories/32/14/32_14_ag_reilly.html

http://rooseveltisland360.blogspot.com/2009/04/can-11-subway-cars-platform-at.html

IND STATION LENGTHS:

http://talk.nycsubway.org/perl/read?subtalk=131809

http://talk.nycsubway.org/perl/read?subtalk=721424

11-car operation on the E and F in the 1950s:

In 1953, the platforms were lengthened to 660 feet at 75th Avenue, Sutphin Boulevard, Spring Street, Canal Street, Ralph Avenue and Broadway–East New York so that E and F trains could run eleven car trains, which began during rush hours on September 8. The extra train car increased the total carrying capacity by 4,000 passengers. 

The problem, however that was mentioned in several posts is that the newer construction on the IND including the stations S/O Bway/ENY only provided for 10 car trains even though the E line did run 11 car trains to Euclid with the last car unopened S/O ENY. 

All the regular stations could handle 11 car trains. It's the reason that the transfer of the Culver Line to the IND resulted in running the D on the Culver and terminating the F in Manhattan. The F had run to Church Ave prior to the Culver transfer.

 

https://timesmachine.nytimes.com/timesmachine/1953/08/28/83735052.pdf

 

"Eleven-car trains were used on both routes from 1953 to 1958, but the TA stopped that bacause of "operational difficulties." The longer train required the motorman to "stop on a dime." Also, signal blocks, especially in Manhattan, were too close together to accommodate 11 -car IND trains."

https://books.google.com/books?id=oZX0AAAAMAAJ&dq="11-car"++1958+subway&focus=searchwithinvolume&q=11-car

https://books.google.com/books?id=AffmAAAAMAAJ&dq="11-car"++"subway"&focus=searchwithinvolume&q="11-car"+

It ended on September 8, 1958-https://issuu.com/erausa/docs/2006-03-bulletin

Edited October 19, 2018 by Union Tpke

[RR503]

Honestly the second CBTC comes online on the full  routes, this should be study #1. Before then, I wonder whether the aforementioned signal block length issues will actually cause 660’ trains to affect a net reduction in capacity — especially given the constellation of shit that our signals are today.

[Ian Lennon]

Won't fleet assignments be a pain with 4, 5, & 6 car sets? The last time they did it, it was still all singles. The only B division trains that were married were the R-27/30. Can't do a single unless it's isolated from the other 10 thanks to non-convertible full cabs. 

[bulk88]

On 9/22/2018 at 3:19 PM, Deucey said:

So if you have more trains running closer together because of CBTC, what happens when those trains that are 700ft apart on QBL meet the 1000ft fixed blocks on the aforementioned lines?

How do you not have severe congestion or uneven service gaps on 6th Av, for example?

NYCT has 20 foot blocks, 100 feet separation, 60 feet ebrake IIRC. MAS is 5 mph or 3 MPH at 100 feet tho. CBTC in NYC has  Headway management. The trains will leave stations early and close down the door if they are late and they will run slower if they are hot between stations or they will hold the door open at the platform until scheduled to depart. conductor knows to the second how early or late he is. bunching is fixed automatic in ATO. +5 or +10 seconds faster between every stop until it's on time. L aggressively uses run non-stop to 8th Avenue to fix schedule problems no other line does that. 

 

Anyways last night I first time ever saw a Queens train run in ATPM mode. Ummmmm, Queens CBTC is unrelated to 7 or L in my opinion. it currently functions as cab signals alone the tracks are solid green is maximum or flashing green if anything less than maximum but blocks are still the Legacy system or AWS and you have a DC Metro problem that the driver just gets penalty / brake at every less than max speed timer. it's like there are no movement authorities and there is no Zone controller it is simply the Legacy fixed block relays sending back aspects over the radio network but you can't even see signal heads down the track, u can only see the current signal head on the display. also the display never does a countdown to the next aspect change if it is a reduced aspect it simply goes into e-brake penalty when you cross the block. the MTA does not trust the system for life safety reasons at this time😡

[Deucey]

12 minutes ago, bulk88 said:

NYCT has 20 foot blocks, 100 feet separation, 60 feet ebrake IIRC. MAS is 5 mph or 3 MPH at 100 feet tho. CBTC in NYC has  Headway management. The trains will leave stations early and close down the door if they are late and they will run slower if they are hot between stations or they will hold the door open at the platform until scheduled to depart. conductor knows to the second how early or late he is. bunching is fixed automatic in ATO. +5 or +10 seconds faster between every stop until it's on time. L aggressively uses run non-stop to 8th Avenue to fix schedule problems no other line does that. 

The thing I was asking is what happens when those QBL trains run on QBL at  or  frequencies in the CBTC zone end up on non-CBTC trackage - 6th Av, Broadway BMT, or 8th Av where there's fixed blocks and interlined services but no wide enough gaps for - example -  to merge at 59th Street and run at the normal speed because three of the next 5 blocks between Lex-59 and 57/7th are red waiting for clearance.

I'm not certain that's what you answered (you gave me academic and tech when I'm an ELI5 guy).

[RR503]

3 hours ago, Deucey said:

The thing I was asking is what happens when those QBL trains run on QBL at  or  frequencies in the CBTC zone end up on non-CBTC trackage - 6th Av, Broadway BMT, or 8th Av where there's fixed blocks and interlined services but no wide enough gaps for - example -  to merge at 59th Street and run at the normal speed because three of the next 5 blocks between Lex-59 and 57/7th are red waiting for clearance.

I'm not certain that's what you answered (you gave me academic and tech when I'm an ELI5 guy).

What it really comes down to is the structure of capacity in the system. The combined  and  run more trains per hour than the  and ,  and ,  and  or  and  -- so you get a bump in throughput on the constraining section (the  sharing on Queens Blvd) while the others run closer to their fixed-block capabilities. 

For those who like maps (with pre-COVID capacity #s): 

https://drive.google.com/file/d/1L2j2vVHrd-WJ6yAgkx3Se4sFKLwraDtD/view?usp=sharing

Edited December 30, 2020 by RR503

[Deucey]

2 hours ago, RR503 said:

What it really comes down to is the structure of capacity in the system. The combined  and  run more trains per hour than the  and ,  and ,  and  or  and  -- so you get a bump in throughput on the constraining section (the  sharing on Queens Blvd) while the others run closer to their fixed-block capabilities. 

For those who like maps (with pre-COVID capacity #s): 

https://drive.google.com/file/d/1L2j2vVHrd-WJ6yAgkx3Se4sFKLwraDtD/view?usp=sharing

Look at you showing up to say hi...Thought you forgot about us...

So how does this translate for rider experience - are those 6 Av trains moving the same as they do now with 15 second dwell times in station and 45 seconds to the next one, or are they crawling with stop-starts or slow speeds in between stations and 30-45+ second dwells because the distance between trains on non-CBTC trackage will be less than the minimum distance the block signaling allows for?

 

[RTOMan]

CBTC is only from Kew to Roosevelt on all four tracks....

Not all trains have CBTC enabled due to lack of personnel qualified..

This GO with the 53rd street tube shut down they are installing more CBTC equipment, they will run test trains through that area.

[RR503]

15 hours ago, Deucey said:

Look at you showing up to say hi...Thought you forgot about us...

So how does this translate for rider experience - are those 6 Av trains moving the same as they do now with 15 second dwell times in station and 45 seconds to the next one, or are they crawling with stop-starts or slow speeds in between stations and 30-45+ second dwells because the distance between trains on non-CBTC trackage will be less than the minimum distance the block signaling allows for?

It’ll be pretty similar to today, just with a few more congestion and merge delays. QB CBTC service plans (pre-COVID, ofc) only projected addition of 1-2tph on each of the  and , which makes for up to 26tph on the segments each shares with the , 25tph on  trackage, and 25tph on . Of course,  sharing will be entirely within CBTC territory, and  presumably will be soon too, which leaves  and  as potential constraints. I think 6th and Culver will be okay with those loads, though, especially now that Church Avenue is working a bit better with the force-and-lock signal mod. 
 

It’s been a busy few months. I’m glad to be back  

Edited December 31, 2020 by RR503

[VIP]

3 hours ago, RR503 said:

It’ll be pretty similar to today, just with a few more congestion and merge delays. QB CBTC service plans (pre-COVID, ofc) only projected addition of 1-2tph on each of the  and , which makes for up to 26tph on the segments each shares with the , 25tph on  trackage, and 25tph on . Of course,  sharing will be entirely within CBTC territory, and  presumably will be soon too, which leaves  and  as potential constraints. I think 6th and Culver will be okay with those loads, though, especially now that Church Avenue is working a bit better with the force-and-lock signal mod. 
 

It’s been a busy few months. I’m glad to be back  

Welcome back! 😉

[bulk88]

NYCT never added TPH to 7, they only lifted a supplement from the 2000s. In any case 7 or L, any trains added are simply avoiding canceled peak trains. QBL pre covid wud be same deal. more E holds at 50 SB Bc E was hot. CBTC QBL is first time I saw the MTA is mixing radio and Legacy trains. 7 and L were forklift cut overs on 1 weekend never going back to fixed block. QBL seems like MTA will never remove the trip cocks and heads. "AWS" forever, double the maintenance parts and double the inspection hours every week.

 

[RR503]

45 minutes ago, bulk88 said:

NYCT never added TPH to 7, they only lifted a supplement from the 2000s. In any case 7 or L, any trains added are simply avoiding canceled peak trains. QBL pre covid wud be same deal. more E holds at 50 SB Bc E was hot. CBTC QBL is first time I saw the MTA is mixing radio and Legacy trains. 7 and L were forklift cut overs on 1 weekend never going back to fixed block. QBL seems like MTA will never remove the trip cocks and heads. "AWS" forever, double the maintenance parts and double the inspection hours every week.

The supplement that was lifted was one which thinned out the pre-CBTC 27 to 25, IIRC, to support switch work. Net increase was 27 => 29. FWIW, the way the pre-CBTC schedule worked (going back at least to 2003, if not earlier) was alternating 120 and 150 second headways, making for an average headway of 135 seconds, or 27tph. 

I would give it a few weeks/months before coming to any conclusions about the status and direction of the QBL cutover. What's going on at the moment is just that -- a cutover! There have, to my knowledge, not been any changes to the end plan.