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| Question about the Queens Blvd CBTC. (1532064) | |
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| (1532065) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Union Tpke on Sun Dec 8 16:46:23 2019, in response to Question about the Queens Blvd CBTC., posted by Chicago44 on Sun Dec 8 16:23:50 2019. I expect 0. However, while 30 TPH are scheduled, in effect 25 TPH run. With CBTC, 30 TPH would actually be provided. |
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| (1532067) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Joe V on Sun Dec 8 17:05:18 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Union Tpke on Sun Dec 8 16:46:23 2019. On the express service. Locals run below capacity without CBTC as it is, always did. |
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(Sponsored) |
iPhone 6 (4.7 Inch) Premium PU Leather Wallet Case - Red w/ Floral Interior - by Notch-It |
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| (1532078) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by randyo on Sun Dec 8 18:20:27 2019, in response to Question about the Queens Blvd CBTC., posted by Chicago44 on Sun Dec 8 16:23:50 2019. The problem may not be just the signal system but the actual number of cars available for service. |
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| (1532079) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Sun Dec 8 18:25:23 2019, in response to Re: Question about the Queens Blvd CBTC., posted by randyo on Sun Dec 8 18:20:27 2019. If, perchance, CBTC allows the trains to move a bit faster, you can increase frequency with the same number of cars. |
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| (1532081) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Train Dude on Sun Dec 8 19:12:50 2019, in response to Question about the Queens Blvd CBTC., posted by Chicago44 on Sun Dec 8 16:23:50 2019. The simple answer is "Zero". While in theory, capacity on Queens Blvd may be increased, once trains get into Manhattan, they will encounter non-CBTC 6th or 8th Ave lines with no increase in capacity. Any additional trains added in Queens would cause gridlock in Manhattan. |
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| (1532092) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Jackson Park B Train on Sun Dec 8 21:16:40 2019, in response to Question about the Queens Blvd CBTC., posted by Chicago44 on Sun Dec 8 16:23:50 2019. fewer than the famous mid 1950s map. |
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| (1532109) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 06:41:08 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Sun Dec 8 18:25:23 2019. If, perchance, CBTC allows the trains to move a bit faster, you can increase frequency with the same number of cars.No. Headway has a minimum vs. train speed that's not dependent on the signal system. |
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| (1532110) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 06:43:36 2019, in response to Re: Question about the Queens Blvd CBTC., posted by randyo on Sun Dec 8 18:20:27 2019. The problem may not be just the signal system but the actual number of cars available for service.Also the dollar cost of providing extra service during rush hours. The absence of split shifts means 4 additional crew members are required for an extra train in both the morning and evening. |
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| (1532116) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 08:19:01 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 06:41:08 2019. Huh?If the trains go faster, they get to their destination sooner and can start a new trip sooner. So you need fewer cars for the same number of trips per day. I understand that perhaps CBTC won't allow shorter headways, but that wasn't the issue. The issue was, wouldn't shorter headways require more cars? And that's not intrinsically true. |
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| (1532117) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Train Dude on Mon Dec 9 08:42:19 2019, in response to Re: Question about the Queens Blvd CBTC., posted by randyo on Sun Dec 8 18:20:27 2019. True. While in the past the TA might have kept a train of older cars to make a rush hour run, it would no longer be feasible to run a consist of semi-retired, non-CBT R46s on the CBTC Queens Blvd line. |
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| (1532120) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Avid Reader on Mon Dec 9 08:52:28 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Train Dude on Mon Dec 9 08:42:19 2019. Will your 3-Rail Club be having an "Open House" this Season?I miss your excellent Videos! Avid |
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| (1532122) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Train Dude on Mon Dec 9 09:01:14 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Avid Reader on Mon Dec 9 08:52:28 2019. Absolutely. Our next open house will be this Weekend. 11AM-4PM both days. I might even be running my Subway Work Train. Stop by and say hello. |
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| (1532126) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by subfan on Mon Dec 9 09:33:59 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Train Dude on Sun Dec 8 19:12:50 2019. In theory, I suppose they could extend the G back to Queens Blvd - but that would also mean re-assigning it to Jamaica Yard and equipping it with new cars.subfan |
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| (1532127) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Joe V on Mon Dec 9 11:13:24 2019, in response to Re: Question about the Queens Blvd CBTC., posted by subfan on Mon Dec 9 09:33:59 2019. With the R46 shifted to CIY, they could use the A-A sets for the Franklin Shuttle, then assemble 8 of the 9 R68's that are singles now into an 8 car main line set, put back the destination signs. |
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| (1532129) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Mon Dec 9 11:48:00 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 08:19:01 2019. A few months ago Stephen posted a mathematical explanation taking into account train speed, train length, acceleration and deceleration rates which gave a theoretical upper limit to trains per hour. Higher speeds do not necessarily increase throughput. |
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| (1532132) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by MTA T on Mon Dec 9 12:25:10 2019, in response to Question about the Queens Blvd CBTC., posted by Chicago44 on Sun Dec 8 16:23:50 2019. It will get a chipper 10 |
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| (1532137) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by FYBklyn1959 on Mon Dec 9 13:07:29 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Joe V on Mon Dec 9 11:13:24 2019. S FKLYN SHUTTLES FRANKLIN AV-FULTON ST (too long?) S FKLYN SHUTTLE S PROSEPCT PARK Or would it be just "S SHUTTLE"? |
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| (1532139) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 13:32:52 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 08:19:01 2019. Huh?Here's the link to the explanation to which Mr. VictorM referred. BTW, the same physics holds for motor vehicles. So, it's a false hope that driverless cars will increase highway capacity. |
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| (1532141) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 13:37:05 2019, in response to Re: Question about the Queens Blvd CBTC., posted by VictorM on Mon Dec 9 11:48:00 2019. Did you attend my presentation at Transportation Camp? |
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| (1532142) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 14:19:23 2019, in response to Re: Question about the Queens Blvd CBTC., posted by VictorM on Mon Dec 9 11:48:00 2019. Higher speeds do not necessarily increase throughput.I never said they did. I said that higher speeds reduce the number of cars you need. Simply because you can run the same number of trips per day with fewer cars because each trip takes less time. No other reason. This is not a deep observation. Why are you and Stephen arguing with me about something so trivial? |
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| (1532143) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 14:21:24 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 13:32:52 2019. You're still trying to rebut something I never said.What I am claiming is analogous to claiming that if taxis could travel faster, you would need fewer of them to meet the same demand. |
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| (1532146) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Edwards! on Mon Dec 9 14:49:17 2019, in response to Re: Question about the Queens Blvd CBTC., posted by FYBklyn1959 on Mon Dec 9 13:07:29 2019. S/Franklin Ave S/Prospect Park |
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| (1532152) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 15:31:21 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 14:21:24 2019. What I am claiming is analogous to claiming that if taxis could travel faster, you would need fewer of them to meet the same demand.Nope. Going faster will not provide meet the same demand, if the speed is greater than the optimum. Consider the extreme of infinite speed. The trip will take 0 time. However, the headway to the next train would be infinite. Thus, it would be a single trip. Good, if that's the demand. Bad, otherwise. |
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| (1532153) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 16:37:29 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 15:31:21 2019. Consider the extreme of infinite speed. The trip will take 0 time. However, the headway to the next train would be infinite Um, there is something seriously wrong with that logic. |
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| (1532154) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 16:58:33 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 16:37:29 2019. there is something seriously wrong with that logic.Not at all. The braking time for the follower is V/a. If V is infinite, then V/a is also infinite. The follower's braking time is one component of headway. Similarly, if V were 0 and the train length were L, then the time for the leader to completely pass a point is L/V. That's also infinite. That's the headway's other component - the time for the leader to pass a point. So, (L/V) + (V/a) has a minimum value somewhere between 0 and infinity. You need a leader and follower to define a headway. |
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| (1532155) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Fisk Ave Jim on Mon Dec 9 17:58:04 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 16:58:33 2019. I knew I never should have dropped physics!!:) |
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| (1532156) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 18:24:10 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 16:58:33 2019. Your analysis assumes that a can't be improved as V is improved (not necessarily proportionately, of course). That is patently absurd. It would leave us all still riding horse-drawn buggies. |
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| (1532158) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Mon Dec 9 18:44:29 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 14:19:23 2019. Higher speeds do reduce the number of cars you need for the same number of trips, but only up to a point. After that any further speed increase, while it reduces the number of cars needed, also reduces the number of trips possible. |
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| (1532159) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Joe V on Mon Dec 9 18:46:18 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Fisk Ave Jim on Mon Dec 9 17:58:04 2019. More like Calculus theories. |
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| (1532160) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Mon Dec 9 18:57:37 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 13:37:05 2019. No, but I now remember it wasn't on this site but on nyctransitforums.com that I saw your analysis. |
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| (1532161) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Mon Dec 9 19:20:00 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 13:32:52 2019. Thanks for the link. |
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| (1532163) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Mon Dec 9 19:32:45 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 18:24:10 2019. Also, even granting that a can't be improved, there must be many factors other than L/V and V/a involved in current train intervals.Say L is 500 feet, V is 50 feet per second, and a is 5 ft/sec^2. Then L/V + V/a is 20 seconds, and yet the interval between trains is 120 seconds. So a little more increase in V/a wouldn't be that harmful. |
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| (1532164) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Mon Dec 9 19:35:24 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 18:24:10 2019. Sure, you can increase a so that the train could avoid hitting the train ahead of it, but would you really want the standing passengers thrown about like ten pins in a bowling alley? |
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| (1532165) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 19:46:33 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 18:24:10 2019. Your analysis assumes that a can't be improved as V is improved (not necessarily proportionately, of course). That is patently absurd.a is the emergency braking rate. NYCT brakes only the wheels. This means the acceleration is limited rolling friction. It's sliding friction, if the wheels lock. Sliding friction braking isn't controlled. Therefore, the emergency acceleration is limited to less than the minimum sliding friction achieved by the steel wheel on steel rail. The coefficient (c) is between 0.35 and 0.5 for a dry contact. That's the ratio of the weight on the rail to the braking force. From 8.01 (F = ma) this means on level track that F = ma = cmg, where m is the mass, c the friction coefficient and g the gravitational acceleration (32 ft/sec). The mass cancels out on both sides of the equation. a = cg = 0.35 * 32 = 11.2 ft/sec-sec = 7.6 mph/sec So, increasing a as a function of V isn't a realistic hypothesis. |
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| (1532168) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Mon Dec 9 19:54:59 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Joe V on Mon Dec 9 18:46:18 2019. I purposely avoided calculus in my presentation. I tried to keep the analysis to the level of high school physics circa 1958. The math is strictly algebra and geometry. |
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| (1532169) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Fisk Ave Jim on Mon Dec 9 19:58:57 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Joe V on Mon Dec 9 18:46:18 2019. Maybe he can help you??:) |
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| (1532184) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Joe V on Tue Dec 10 06:40:16 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 19:54:59 2019. A saw "infinite", so thought limits and calculus. (I never took physics). |
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Re: Question about the Queens Blvd CBTC. |
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Posted by TransitChuckG on Tue Dec 10 07:25:29 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Joe V on Tue Dec 10 06:40:16 2019. I never did well in Engineering courses. Intergral Calculus was the killer! |
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Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Tue Dec 10 08:00:22 2019, in response to Re: Question about the Queens Blvd CBTC., posted by VictorM on Mon Dec 9 19:35:24 2019. You guys still haven't addressed that V/a is a very small fraction of the actual time between trains.Also, of course, that L/V + V/a doesn't change much at all if you increase V by a moderate percentage. |
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| (1532192) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by cortelyounext on Tue Dec 10 08:51:05 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Stephen Bauman on Mon Dec 9 19:46:33 2019. Stephen, I had every intention of entering this thread with extreme prejudice to set the record straight. As arguably the leading male stewardess here, I by all accounts possess the most enlightened mind on this board and, to a lesser extent, BusChat with respect to the classical languages, theoretical physics in general and quantum field theory in particular, and what I thought was advanced mathematical formulae, that is, until your post. After following this thread with serious contemplation, I have come to a monumental decision. I, my friend, have reached the fork in the road and have chosen instead to bow out gracefully. Other than AIM or ALM or A1M whoever zir is I am the only one who can seriously challenge you within the context of this subject matter but when I see defeat staring me squarely in my face I know to cut my losses and follow the tenets of Sun-Tzu, so as to live to fight another day, and Major General Nathanael Greene, he of the 138th Rhode Island Tactical Fighter Squadron (Heavy) Artillery who during the Revolutionary War left these immortal words to posterity:"We fight, get beat, rise, and fight again." To better illustrate my point: Fork in the Road |
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Re: Question about the Queens Blvd CBTC. |
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Posted by cortelyounext on Tue Dec 10 08:58:11 2019, in response to Re: Question about the Queens Blvd CBTC., posted by cortelyounext on Tue Dec 10 08:51:05 2019. That was a good post right there. It adds absolutely nothing of merit to this thread, but it was a good post nonetheless. |
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Re: Question about the Queens Blvd CBTC. |
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Posted by VictorM on Tue Dec 10 09:10:59 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Tue Dec 10 08:00:22 2019. That link Stephen referred to above gives much more realistic analysis. He's not saying increasing the speed does not reduce the number of trains needed; only that there is is a certain speed which gives maximum throughput. |
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Re: Question about the Queens Blvd CBTC. |
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Posted by AlM on Tue Dec 10 09:37:41 2019, in response to Re: Question about the Queens Blvd CBTC., posted by VictorM on Tue Dec 10 09:10:59 2019. He's not saying increasing the speed does not reduce the number of trains neededThen why has everyone been arguing with me about what seems like a very trivial point? I never claimed that increasing speed worked ad infinitum. |
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Re: Question about the Queens Blvd CBTC. |
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Posted by Train Dude on Tue Dec 10 11:24:51 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Mon Dec 9 19:32:45 2019. Of course your (a) is double the value that the TA uses in it's car design. |
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| (1532200) | |
Re: Question about the Queens Blvd CBTC. |
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Posted by Train Dude on Tue Dec 10 11:34:06 2019, in response to Re: Question about the Queens Blvd CBTC., posted by AlM on Tue Dec 10 09:37:41 2019. Maybe it's because you emphasized increasing (a) in your earlier comment. (A) as a design criteria has been fairly consistent over at least the last 40 years that I know of and we are not riding in a buggy yet. |
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Re: Question about the Queens Blvd CBTC. |
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Posted by cortelyounext on Tue Dec 10 13:25:56 2019, in response to Re: Question about the Queens Blvd CBTC., posted by cortelyounext on Tue Dec 10 08:51:05 2019. Hereuh oh |
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Re: Question about the Queens Blvd CBTC. |
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Posted by cortelyounext on Tue Dec 10 13:28:20 2019, in response to Re: Question about the Queens Blvd CBTC., posted by cortelyounext on Tue Dec 10 13:25:56 2019. Only because this was a good thread...Last One |
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Re: Question about the Queens Blvd CBTC. |
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Posted by cortelyounext on Tue Dec 10 13:30:21 2019, in response to Re: Question about the Queens Blvd CBTC., posted by cortelyounext on Tue Dec 10 13:25:56 2019. Genius |
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Re: Question about the Queens Blvd CBTC. |
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Posted by Stephen Bauman on Tue Dec 10 14:26:01 2019, in response to Re: Question about the Queens Blvd CBTC., posted by Train Dude on Tue Dec 10 11:24:51 2019. Of course your (a) is double the value that the TA uses in it's car design.Look at the fine print. a is 5 ft/sec^2 That's equivalent to 3.4 mph/sec. That's double the current 3.0 mph/sec spec. It's still higher than current fleet specs but half that of the Bluebirds. |
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