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| Re: TA is obsessed with CBTC, and ''New'' tech for no reason. (578118) | |
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| (579447) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Sun Mar 2 13:19:00 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Fine, Howard, and Fine on Sun Mar 2 13:05:57 2008. 'Cab codes' is a new one for me - I've heard of 'cab signal codes'; I assume it's just a shortening of that? |
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| (579448) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Wado MP73 on Sun Mar 2 13:19:25 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 10:36:15 2008. My understanding is that while all ATO and ATC are communication based train control, when you use the term CBTC now, it has to conform to the IEEE Std 1474. Of course, I could be wrong.The same page has a link to a 1997 speech by the LIRR president. Interesting... |
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| (579452) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Sun Mar 2 13:31:21 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Wado MP73 on Sun Mar 2 13:19:25 2008. Thanks for the report.Whatever happened, LIRR changed direction drastically. Here's a big line, on my reading from the former LIRR President's address, The role of CBTC on the LIRR can be summarized very simply: It is our intention that CBTC will be installed exclusively on the entire railroad. It is apparent that commitment to CBTC must be an "all-or-nothing" proposition in the long run. The realities of economics are such that no property will be able to support what amounts to two distinct signal systems. Meanwhile compare to this from the Sept. 2007 Nelson Report, It appears that LIRR lost several years in its signal upgrade program during the 1990’s when there was a flirtation with “Communication Based Train Control,” an untested technology in heavy rail at that time. A cursory review of the capital program reveals very little concern with replacing or upgrading the system until the current program. I noted that C & S had requested $57.8 million in each capital program to date for State of Good Repair. In the 200509 program they received only $5.4 million! That amount for SGR of the existing system was included in the overall level of about $200 million for new systems; the CTC program and related signal upgrade projects. The recently completed new color-light system installed between Patchogue and Speonk should be the way of the future for modernizing the LIRR Signal System. A modern, color-light, solid-state system without wayside signals (except at interlockings) and cab signals is an efficient, proven and very safe system. That installation was designed, wired, constructed and installed with inhouse forces and took six (6) years. It was a “very bad experience” according to the ACEC & S. The next segment, Babylon to Patchogue, will utilize outside vendors for design, CIL manufacture, wiring and setup. The railroad will handle the grade crossing work, hot connections to the railroad’s operating system and final testing. I certainly agree with that approach. There is no need to reinvent the wheel, especially where technological advances come almost daily. Learn from the experiences of others and avoid the risks of being too far out in front. It will save time, energy and money. The Patchogue-Babylon signal project is only half funded. It is a $50 million project already cut to about $25 million, and reportedly in jeopardy to be reduced again. I would strongly urge the railroad to fully fund this project now. The signal system is the nerve system of the railroad operation and has been neglected too long. This project could, and should, be accomplished in 3 years with assured funding. |
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iPhone 6 (4.7 Inch) Premium PU Leather Wallet Case - Red w/ Floral Interior - by Notch-It |
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| (579472) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Wado MP73 on Sun Mar 2 14:17:36 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 13:31:21 2008. Right?OTOH, Googling in French me gave more confusion about the definition of CBTC. They all say about this "next generation" and "latest generation" of train automation/control but nobody seems to be willing to clearly define it. RATP's line 14 is CBTC but classic ATO on other lines isn't. |
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| (579483) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by SelkirkTMO on Sun Mar 2 14:53:53 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Sat Mar 1 08:52:54 2008. Gettin' lazy in yer old age, eh? =) |
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| (579484) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Wado MP73 on Sun Mar 2 14:54:50 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Wado MP73 on Sun Mar 2 14:17:36 2008. CBTC definition according to the Institution of Railway Signal EngineersCBTC = Communications Based Train Control The primary characteristics of a Communications-Based Train Control (CBTC) system include: - High resolution train location determination, independent of track circuits - Continuous, high capacity, bi-directional train-to-wayside data communications - Trainborne and wayside processors performing vital functions The non-use of track circuits will already disqualify many older ATO systems. |
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| (579485) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by SelkirkTMO on Sun Mar 2 14:54:52 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by South Brooklyn Railway on Sat Mar 1 08:45:01 2008. Congrats, guy! |
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| (579494) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by R30A on Sun Mar 2 15:24:39 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Sun Mar 2 09:23:59 2008. If CBTC was not problematic, all the cars equipped with such would be using it on the L line. |
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| (579497) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Sun Mar 2 15:29:01 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Wado MP73 on Sun Mar 2 14:54:50 2008. Just one clarification:The non-use of track circuits will already disqualify many older ATO systems. should read, I think, either: "The non-use of track circuits criterion will already disqualify many older ATO systems." Or: "The use of track circuits will already disqualify many older ATO systems." But a request for further clarification - does NYCT's signal system on the Canarsie Line use track circuits for wayside signals? |
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| (579498) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Bill from Maspeth on Sun Mar 2 15:32:55 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Sun Mar 2 09:23:59 2008. Sometimes matters that are not problematical in other systems are problematical at NYCT. Starting a new system with CBTC vs. converting an old system to CBTC brings about many challenges. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Sun Mar 2 15:45:44 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Bill from Maspeth on Sun Mar 2 15:32:55 2008. Both BART and LIRR would have been conversion efforts. PATH will be a conversion effort as well too. All of these would have been to RF-CBTC technology. MUNI used an earlier inductive loop CBTC technology, so in a way, it's a different comparison.It's was problematic on BART too, per this. LIRR apparently reversed its original gung ho pro-CBTC stance. We'll see how it goes on PATH. |
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| (579507) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 15:58:24 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 13:19:00 2008. CSC? ABC, XYZ? PDQ!8-) |
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| (579510) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 16:02:47 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 15:45:44 2008. Thanks for posting that. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 16:12:20 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Bill from Maspeth on Sun Mar 2 15:32:55 2008. Very true. |
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| (579516) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 16:14:10 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by R30A on Sun Mar 2 15:24:39 2008. False statement. |
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| (579519) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Broadway Buffer on Sun Mar 2 16:22:11 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by mr_brian on Sat Mar 1 16:59:54 2008. I've heard it said that some physicists believe that even if a time-machine is to be invented, it would still be impossible to go back to the past since it doesn't exist. However, it might be possible to go forward into the future since although it is yet to exist, there is "potential" for it.So if this is true, it means bad news for those who dream of returning to a railfan-window rich, CBTC-poor system but good news for those interested in taking their first ride on an R-796 and future car-classes with CBTC/ATO systemwide ... perhaps. :-) |
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| (579530) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by R30A on Sun Mar 2 16:56:55 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Sun Mar 2 16:14:10 2008. How?How is broken not problematic? |
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| (579533) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 17:09:40 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Broadway Buffer on Sun Mar 2 16:22:11 2008. A creative theory, to be sure... |
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| (579535) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Sun Mar 2 17:11:25 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by R30A on Sun Mar 2 16:56:55 2008. You said CBTC is problematic. Far too general and simplistic.New York's CBTC implementation is having problems. |
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| (579540) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Wado MP73 on Sun Mar 2 17:20:17 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 15:29:01 2008. You got that right.does NYCT's signal system on the Canarsie Line use track circuits for wayside signals? I assume so. Otherwise there is no way to tell the position of non-CBTC trains. |
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| (579543) | |
Re: What does CBTC really mean? |
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Posted by RonInBayside on Sun Mar 2 17:29:55 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Wado MP73 on Sun Mar 2 17:20:17 2008. Something occurred to me:Analogy: Fixed block system = structured CBTC = Object oriented. In object oriented programming, objects have attributes and communicate with other objects, whereas in structured programming, the overall system controls the variables within it. CBTC brings an object oriented approach to running a railroad. This concept is very powerful and offers a lot of capability even beyond running trains closer together. CBTC will ultimately win out over other types of signaling in the long haul, for reasons not dissimilar to why object oriented programming has taken over from structured programming in most spheres... |
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| (579551) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason.(Sorry I was not Home) |
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Posted by North-Easten T/O on Sun Mar 2 17:51:19 2008, in response to TA is obsessed with CBTC, and "New" tech for no reason., posted by JournalSquare-K-Car on Thu Feb 28 22:08:34 2008. I am sorry now for not being home, but I was on a family voaction and was having more fun there. But If I was here I would have put more into the disction about CBTC, but it look like Rail and Dave both did a great job tell people about the system. The one thing I will add to one about distents and Speed controll of CBTC. The CBTC system slows the train down as it get closer to what ever is in front if it, by time you get within 75ft our only going to be doing 4mph and at 30ft and less then your lucky if your going 2mph, and if you try to go over that the train will go BIE and tell everyone you did so.Robert |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason.(Sorry I was not Home) |
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Posted by RonInBayside on Sun Mar 2 17:52:21 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason.(Sorry I was not Home), posted by North-Easten T/O on Sun Mar 2 17:51:19 2008. Great feature there - a very intelligent system. |
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| (579687) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Stephen Bauman on Sun Mar 2 21:23:30 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Sun Mar 2 01:18:48 2008. I think what you are missing is that SB is comparing actual CBTC performance to conventional signal performance in a different time period.Several things have happened since the peak service levels of the 1950s which have cut into the ability of the fixed wayside system. Most of them have to do with trusting, or rather NOT trusting the person in the cab. Before you reach that conclusion, might I suggest you perform the following thought experiment. Decide on a minimum separation between trains, where the follower will not encounter any red or yellow signals and the follower does not have to come partially into a station. Next, remember with the scenario of the follower approaching a station occupied by its leader that the minimum distance will be achieved when the departing leader reaches the speed of its approaching follower. First: determine how long and how far the leader will travel in reaching this velocity. Second: assume the follower is the requisite distance behind the leader at the instant the leader has reached the same velocity as the follower. Third: calculate the time it takes the follower to come to a complete stop in the station. Fourth: add the times from the first and third steps, add 30 seconds for dwell time within the station to come up with a figure for the minimum headway. If this minimum headway is comparable to those from the halcyon days of the 1950's, then keying-by and partial station entry are not required for such headways. Let us begin by making some realistic assumptions for the minimum distance and the maximum velocity. I'm going to assume 1200 feet and 30 mph. The 1200 foot separation should insure that the follower never encounters a yellow signal (let alone a red signal) approaching the station. It also means that when the follower enters a 600 foot long station the leader is another 600 feet beyond it. Feel free to suggest another value, remembering that the object is to guarantee only green signals in coming to a stop. The 30 mph seems reasonable in today's environment. Next, we need to calculate the time and distance taken by the leader in accelerating to 30 mph. I can think of 3 methods to accomplish this. The first is a pre-computer engineering approach of assuming a uniform acceleration remembering that all we are interested in is where and when. The second is the multi-million consultant approach of taking the aceleration profile of the equipment and numerically integrating it with a Runga-Kutta program to get the leader's speed and distance traveled as a function of time. The third is to take a stopwatch and time trains leaving stations. I've tried all three approaches. For ease let's take the first approach by assuming an average acceleration of 2.0 mph/sec. Thus the leader will reach 30 mph in 15 seconds and travel 330.75 feet. Let's assume 600 foot trains. We want the follower to be 1200 feet behind the leader's rear car. So the follower is 869.75 feet from the station entrance and 1469.25 feet from its stopping point at the front of the station. Now let's bring the follower to a complete stop. We could assume a well-trained T/O who would apply the full service braking rate of 3 mph/sec and take 10 seconds and 220.5 feet to stop the train. However, let's assume a timid T/O who brakes at an average rate of 2.0 mph/sec. The train will 15 seconds and 330.75 feet to stop. This means that the train will continue traveling at 30 mph for 1138.5 feet and take 25.8 seconds. Thus the total time for the follower to come from 1200 feet behind its leader to a complete stop is 40.8 seconds. This brings the minimum headway with 30 seconds of dwell time to: 15 + 40.8 + 30 = 85.8 seconds. This is equivalent to 41.95 tph. Clearly, keying by and station time were not necessary for the 30, 32, 34 and 36 tph peak service levels of the 1950's (through early 1970's). They occurred but they were an anomaly not a necessity. That still leaves door enablers and pointing. Strictly speaking, these activities do not add to dwell time but to braking time. (The definition of dwell time is the interval from when the doors open until when the train starts leaving.) Allow a generous 5 seconds total for the T/O and C/R to agree on which side to platform and for the C/R to give the monitor board the finger. That brings the minimum headway up to 90.8 seconds or 39.6 tph. That's close enough to 40 tph for government work. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Pelham Bay Dave on Mon Mar 3 02:47:31 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Sat Mar 1 16:15:47 2008. I don't know if it would work but they could always test it which I know they won't. They will get ATO working before that happens and all you need to do with that is hit a buttion to start the train. |
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| (579790) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Jeff H. on Mon Mar 3 03:19:39 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Stephen Bauman on Sun Mar 2 05:58:59 2008. That's what I meant by there being an analogy to the Nyquist Sampling Theorem with accelerationtaking the place of frequency. I'm clearly viewing the wayside signals and block system as a sampled data system. I'd rather not get into a more detailed explanation involving z-transforms. I try to limit myself to high school math in my posts and quite frankly my z-transform knowledge is a bit rusty after 40 years. I know what s-z transforms are, but they are just marginally useful here. Now that you put it in terms of the samping theorem and Nyquist rates, I understand your earlier remark. BUT, what's the cost of raising the sampling rate? Plug in some numbers to your formulae. I think you'll find that in order to control speed to the same level as a continuous signal system, even allowing for enforcement delay of the latter, you would need to space signals every 100 feet, maybe less. Operators are permitted to look ahead to the next wayside signal. I believe it is encouraged. If they can see it! Curves, tunnels, etc. A downgrade on the current block after the follower has entered it suggests that the leader has crossed an IJ in the direction going towards the follower. Read what I said again, carefully. If a CONTROLLED signal is dropped. That means an interlocking or approach signal which is under tower control. |
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| (579791) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Jeff H. on Mon Mar 3 03:29:34 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Sun Mar 2 09:53:00 2008. Train B's engineer is proceeding at restricted speed prepared tostop well within her field of sight. But let's say that she nods and the train continues at or below restricted speed (which let's stipulate that under the rules of this railroad is 10 mph - still more than enough to cause a bad collision). If train B's engineer doesn't receive the 'ringer' downgrade until the block boundary, it seems perhaps too late to prevent a collision with train A There are two types of ASC systems. Most railroads use a 0-code to mean "restricting", which is usually 15 MPH, and prepared to stop WITHIN HALF RANGE OF VISION. Failure of engineers to obey the definition of RESTRICTING is a frequent cause of accident. Again, remember the premise: the engineer is competent and wants to live. When you get a restricting, you are supposed to be of the mindset that bad shit could be just around the corner. The idea of the signal system is to prevent you from missing a signal and then slamming into a stopped train at 100 MPH. Likewise, when you are in the yard, there is often no signal control at all. What stops you from hitting things there? This is ASC, not driverless ATO. Transit systems often use a stricter ASC in which the 0 code is a stop and a different code (often 75) is used for 15 MPH. |
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| (579794) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Jeff H. on Mon Mar 3 03:58:47 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Stephen Bauman on Sun Mar 2 21:23:30 2008. Clearly, keying by and station time were not necessary for the 30, 32, 34 and 36 tph peak service levelsof the 1950's (through early 1970's). They occurred but they were an anomaly not a necessity. Your thought experiment is too long-winded for me...I would have to draw it out to follow what you are saying. I have some documents that the BOT used to lay out the IND signal system. They start with a required service level and then plot a series of time-distance-speed curves on huge pieces of graph paper, using the actual grades and acceleration and braking profiles. They reach the conclusion that station time IS necessary in many cases to reach 40 tph (90 second headways). I'm not sure why you reach a different conclusion. You may be neglecting the fact that signal system has an overlap. There are always at least two red signals in approach to the stopped train. If you assume a block length of 600', there is a red at the station entrance, a red 600' back, and a yellow 1200' back. The follower would need to be 1800' to see all greens. As for keying-by, of course that was not intended to be required to meet service under ordinary conditions. However, when there was a variation in dwell time causing bunchng (often beyond the crew's control, e.g. door holding) then keying-by allowed better recovery from the disturbance. |
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| (579795) | |
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by SelkirkTMO on Mon Mar 3 04:11:42 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Mon Mar 3 03:58:47 2008. Just to attest, it was rare northbound into 59/CC to *not* enter on station time with a train leaving as I was entering during rush hour, just as we were instructed to "wrap it" leaving to allow trains to enter behind us and to not leave until as we had a clear leaving. As to keying by, it was rarely needed but encouraged. In fact, where there was a risk, there were "NO KEY BY" signs by the ball requiring that we call in before keying by. I remember 7th Ave (53) N/B being one of those - there were others, but not many. And when you called in at 7th for permission, it was almost always given. They'd tell you where your leader was and to use caution. Amazingly, nobody got rear-ended. :)I agree wholeheartedly in disgust that the modus operendi is that every motorperson on the railroad is mentally ill ... :( |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Stephen Bauman on Mon Mar 3 08:46:02 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Mon Mar 3 03:19:39 2008. I know what s-z transforms areGee, my remarks seem condescending on second reading. I did not intend them to be. Please accept my apologies. what's the cost of raising the sampling rate? Plug in some numbers to your formulae. I think you'll find that in order to control speed to the same level as a continuous signal system, even allowing for enforcement delay of the latter, you would need to space signals every 100 feet, maybe less. Agreed. I was merely pointing out that conventional wayside signals can provide the same level of speed control protection as coded track signals. BTW, I believe the BRT installed signals every 100 feet on the Brooklyn Bridge a century ago (when cable propulsion was replaced). The stated purpose was to enforce the bridge's weight constraints which mandated 700 foot spacing between trains. There were also speed constraints on the trains, I do not recall whether or not the signals also had timers or relied on the T/O's. Curves, tunnels, etc. See around curves? I'd do it with mirrors (or an occasional repeater). That means an interlocking or approach signal which is under tower control. You mean a tower operator can throw a switch open, while a train is barreling towards it? Just what was the design spec for that interlocking? |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Railman718 on Mon Mar 3 08:51:00 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Stephen Bauman on Mon Mar 3 08:46:02 2008. You mean a tower operator can throw a switch open, while a train is barreling towards it?I dont know about a switch,but they can drop a HomeSignal(Put it to danger) RIGHT in front of you.. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Mon Mar 3 09:14:30 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Mon Mar 3 03:29:34 2008. Thanks for the analysis of my scenario.Again, remember the premise: the engineer is competent and wants to live. It's a good premise, I think, and it's going to lessen the impact of any conditions, for sure. Then again, is it a premise that NYCT buys? I don't know about that. Maybe they're meaning to put in an 'idiot-proof' system - no disrespect meant by me to our operating personnel here, mind you, since that word has been thrown around casually in a way I'm not fond of. I don't think that my scenario was realistic in that it's probably difficult for the engineer to nod off after she brought her train's speed down to restricting, although stranger things have happened, e.g., like here, where a NYCT train apparently unintentionally keyed by a red signal and then accelerated up to speed right into the rear of another train. But that's why we have engineer training, I guess, although maybe NYCT has lost faith in that; I certainly couldn't say. Transit systems often use a stricter ASC in which the 0 code is a stop and a different code (often 75) is used for 15 MPH. I wonder if LIRR is an oddball; I seem to recall that their '75' codes something like 25-35 mph, at least in EMUs. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Stephen Bauman on Mon Mar 3 09:38:24 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Jeff H. on Mon Mar 3 03:58:47 2008. Your thought experiment is too long-winded for me...I would have to draw it out to follow what you are saying.Your last paragraph indicates that you accept my conclusion so you may be spared that agony. However, I think there is benefit in examining it thoroughly. I have some documents that the BOT used to lay out the IND signal system. They start with a required service level... What an arcane design approach! If you assume a block length of 600', there is a red at the station entrance, a red 600' back, and a yellow 1200' back. The follower would need to be 1800' to see all greens. I'm assuming a block length less than 600 feet. First off, the average distance between signals on the system is 350 feet (from one of the TA's presentation slides before the start of CBTC). Secondly, empirical inspections indicate that signals in and around stations are generally 300 feet apart or less. Thus, I assumed that if the follower were 1200 feet back, it would see all greens. However, if you want 1800 foot separation, then that translates to an additional 13.3 seconds for the follower to come to a complete stop in the station. That would bring the minimum headway to 99.1 seconds for 36.3 tph. One reason I went into detail was to present an analytical framework for determining headways for various signaling strategies. One merely has to place the follower at the appropriate distance from the leader and calculate the time for the follower to come to a complete stop. As for keying-by, of course that was not intended to be required to meet service under ordinary conditions. However, when there was a variation in dwell time causing bunchng (often beyond the crew's control, e.g. door holding) then keying-by allowed better recovery from the disturbance. Eureka! There are variations! Their cause is immaterial. How to deal with them? There are two approaches: reduce them to insignificance or introduce a mechanisms to live with them. I'd assume those BOT design documents date from the 1920's. Reducing the variations to insignificance requires time standard and clocks throughout the system that are synchronized to that standard time. That technology wasn't available back then. The technology, in the form of keying by and station timers, were available. Their introduction could reduce the effect of the variations, which could not be reduced with the technology then available. Technology changes. Time synchronization is child's play, unless you are trying to set up, operate or use a Windows based time server. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 09:42:08 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Stephen Bauman on Mon Mar 3 08:46:02 2008. "Agreed. I was merely pointing out that conventional wayside signals can provide the same level of speed control protection as coded track signals."No. A skilled, seasoned T/O provides that protection through savvy contextual interpretation of signals. Coded track signals extend that protectionro situations involving less experienced or less skilled personnel. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 09:45:19 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Mon Mar 3 09:42:08 2008. It would also protect trains where the operator cannot see following signals...and a mirror around a corner is not sufficient. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Mon Mar 3 09:52:13 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Mon Mar 3 09:42:08 2008. A skilled, seasoned T/O provides that protection through savvy contextual interpretation of signals. Coded track signals extend that protectionro situations involving less experienced or less skilled personnel.Really? This isn't hermeneutics. I would imagine that NYCT's color aspects of signals are something that every single person qualified to operate a train must know. I don't see where the 'interpretation' comes in. Maybe you meant to pick out a different word; I'm not following.... Yellow over yellow displayed at a signal seems to mean something very clear; it's not as though it's something that one engineer should be able to 'interpret' one way, and another in a different way. Our ordinary outrage at drivers on local streets makes that clear, right: 'How much more GREEN does he want the light to get before he moves?!' |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 09:52:46 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 08:51:00 2008. While you're at 60 mph in the 60th Street tunnel with 60 foamers crowded around your cab on the 60th day of the year. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 09:55:44 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Mon Mar 3 09:52:13 2008. I'm not referring to the interpretation of the signal itself.I'm referring to the interpretation of how you obey them. You can anticipate early and do a gemntle slow down. Or you can do it jackrabbit style. The analogy is the skilled limousine driver versus the rookie 16 year old who just got his license. They both know the rules of the road. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Mon Mar 3 10:01:50 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Mon Mar 3 09:55:44 2008. OK, but I'm still not following how 'coded track signals' are going to help ensure smoother stops versus plain wayside signals. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 10:04:17 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Mon Mar 3 10:01:50 2008. First, the signal you observe is in your cab, so you never have to worry about whether or not you can see it.Second, reread Jeff's description carefully: Link here |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Railman718 on Mon Mar 3 10:06:49 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Mon Mar 3 09:52:46 2008. While you're at 60 mph in the 60th Street tunnel with 60 foamers crowded around your cab on the 60th day of the year.There arent any HomeSignals in the 60th Sstreet tube.. Thre is one Just before the Portal and one at Lexington ave going southbound. Im on the November two days a week so i know this. Now if a Automatic "flashes" on you in those tubes oh boy talk about a "walk of champoins" trying to find out where it is and getting to it to make sure that stop arm went down. The faster you are going if you go BIE the stop isnt as bad to the passengers the slower you are going, the harder the stop can be and somebody could get hurt. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Terrapin Station on Mon Mar 3 10:07:44 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 10:06:49 2008. There arent any HomeSignals in the 60th Sstreet tube..Ron likes to lie here. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by monorail on Mon Mar 3 10:09:52 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Terrapin Station on Mon Mar 3 10:07:44 2008. he likes to lie in the 60th street tube?????????????????????????????? |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Mon Mar 3 10:10:34 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 10:06:49 2008. There arent any HomeSignals in the 60th Sstreet tube..Thre is one Just before the Portal and one at Lexington ave going southbound. And if you're doing 60 mph at either of those signals, you might have some other problems too, I imagine. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 10:10:51 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 10:06:49 2008. 8-) |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Railman718 on Mon Mar 3 10:14:16 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by trainsarefun on Mon Mar 3 09:52:13 2008. I would imagine that NYCT's color aspects of signals are something that every single person qualified to operate a train must know.Yes to the LETTER really you take a Signals Quiz while you are in Schoolcar NOTHING less than a 100% is acceptable, you get one question wrong you hand in your tools on the spot. Even then T/O's still screw up... That Yellow Automatic with the illuminated "S" you past time after time after time was a bit different,you didnt even notice it so you keep your same speed through the area... That "S" wasnt illuminated that signal aspect was a "Solid" Yellow.. So right around that bend here starting you in the face is a Red Over Red HomeSignal.. Guess what happens next? |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by trainsarefun on Mon Mar 3 10:14:31 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by RonInBayside on Mon Mar 3 10:04:17 2008. Yes, cab signals have advantages in some circumstances, but how is this going to help, by your lights, the novice engineer to make 'smoother' stops instead of 'jackrabbit' stops? |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by Railman718 on Mon Mar 3 10:15:24 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Terrapin Station on Mon Mar 3 10:07:44 2008. Actually i think he was joking with that analogy.. |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 10:16:10 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 10:14:16 2008. You call your mother and say, "Hey come over quick! Wanna see me crash?" |
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Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
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Posted by RonInBayside on Mon Mar 3 10:17:13 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Railman718 on Mon Mar 3 10:15:24 2008. Did I neglect to mention that it was also the day coinciding with the 60th total lunar eclipse since the 60th Pope started keeping count? |
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