Jump to content
Attention: In order to reply to messages, create topics, have access to other features of the community you must sign up for an account.
Sign in to follow this  

QBL CBTC: I need an explanation...

Recommended Posts

1 hour ago, Deucey said:

So in effect, all CBTC is doing is spending a large amount of money to do what (NYCT) did before (MTA) 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 (7) 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 (J) 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 by RR503
  • Upvote 5

Share this post

Link to post
Share on other sites

@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






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.




"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."



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

Edited by Union Tpke
  • Upvote 2

Share this post

Link to post
Share on other sites

Honestly the second CBTC comes online on the full (E)(F) 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.

Share this post

Link to post
Share on other sites

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. 

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.