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| CBTC + Short Turn Terminals = Affordable 40tph. (1228421) | |
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| (1228430) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Chris R16/R2730 on Wed Jun 12 18:27:26 2013, in response to CBTC + Short Turn Terminals = Affordable 40tph., posted by Outside the Box on Wed Jun 12 17:48:16 2013. You can't even get to 24 TPH on the Lex local because of dwell times. It's more complicated. |
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| (1228437) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Stephen Bauman on Wed Jun 12 19:04:41 2013, in response to CBTC + Short Turn Terminals = Affordable 40tph., posted by Outside the Box on Wed Jun 12 17:48:16 2013. It reduces conflicts at merges and at grade crossings. The grade crossings north of 135th st on Lenox Ave or Myrtle and Bway BklynA grade crossing like 135th & Lenox does not require CBTC. It should not reduce capacity. All that is required is that north and southbound trains for the same branch are scheduled to approach the grade crossing at the same time. |
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| (1228444) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Stephen Bauman on Wed Jun 12 19:24:26 2013, in response to CBTC + Short Turn Terminals = Affordable 40tph., posted by Outside the Box on Wed Jun 12 17:48:16 2013. Considering yard constraints and real estate acquisition challenges, sustaining 40tph, with the train lengths we have today, would require short turn terminals. The presently overcrowded sections would run 35-40tph, while sections farther out get 10-20tph.Actually, terminal capacity has been reduced because of design changes to make them fail safe for CBTC equipped rolling stock. Prime examples are Jamaica Center and the now defunct South Ferry terminals. CBTC cannot control interlockings. They are operated by a standard block system. Cutting out the brake system in the front disables the brakes in half the train length. The protective trippers for interlockings have been moved 300 feet back to avoid a repeat of the Roosevelt Ave wreck, Moving the interlockings 300 feet distant from the station is what has reduced terminal capacity. |
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| (1228445) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Stephen Bauman on Wed Jun 12 19:26:37 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Chris R16/R2730 on Wed Jun 12 18:27:26 2013. You can't even get to 24 TPH on the Lex local because of dwell times.Dwell time is proportional to headway. Reduce headways and dwell time will be reduced. |
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| (1228447) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Chris R16/R2730 on Wed Jun 12 19:42:06 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Stephen Bauman on Wed Jun 12 19:26:37 2013. People will hold train doors no matter how close the next train is. Reducing train door holding requires a behavioral, not technological solution. |
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| (1228455) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by j trainloco on Wed Jun 12 21:25:00 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Stephen Bauman on Wed Jun 12 19:24:26 2013. CBTC and unitizing of trains are two different things. Even if CBTC were not being implemented, trains would still be unitized. |
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| (1228474) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Sand Box John on Wed Jun 12 23:03:51 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Stephen Bauman on Wed Jun 12 19:26:37 2013. Dwell time is proportional to headway. Reduce headways and dwell time will be reduced.This is basically what I have been saying down here in WMATAland to the folks that are buying the propaganda coming out of WMATA stating they can't run more the 26 TPH on the trunks. The tran control and signaling system is designed to accommodate 40 TPH.  John in the sand box of Maryland's eastern shore. |
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| (1228494) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Stephen Bauman on Thu Jun 13 07:23:20 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Sand Box John on Wed Jun 12 23:03:51 2013. Increase ATC design headway from 90 seconds to 135 seconds????That's quite a performance hit. |
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| (1228501) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Lou from Brooklyn on Thu Jun 13 08:04:10 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Chris R16/R2730 on Wed Jun 12 19:42:06 2013. Short turn trains and I bet your dwell time goes up. New Yorkers won't notice the train is not the one they want. And when they clear the train at the short turn terminal you will have stragglers and "non-movers" complaining about needing to change trains. |
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| (1228505) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Sand Box John on Thu Jun 13 08:33:12 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Stephen Bauman on Thu Jun 13 07:23:20 2013. That's quite a performance hit.Not really that big of a deal, the Silver line is a branch off of a branch. It still leave enough room to exclusively run trains on the branch between through trains that run through the urban core. John in the sand box of Maryland's eastern shore. |
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| (1228514) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Jackson Park B Train on Thu Jun 13 11:18:40 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Sand Box John on Wed Jun 12 23:03:51 2013. CTA could do 90 sec, actually scheduled 1:06 w/ 1940s/50s relays and wayside signals. This is shameful. |
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| (1228522) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Jersey Mike on Thu Jun 13 12:29:08 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Jackson Park B Train on Thu Jun 13 11:18:40 2013. Didn't much of the CTA used to be run on sight back in the day? Either way traditional ABS with very short signal blocks and relying on the operators to make safety critical decisions will drop your headways significantly. See modern day Boston Green Line. |
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| (1228541) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by randyo on Thu Jun 13 13:47:34 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Stephen Bauman on Wed Jun 12 19:04:41 2013. Just because trains are "scheduled" a certain way on paper (or on a computer) doesn't mean that it will show up that way in the real world. Variable such as passenger interference and other conditions impact on the on time performance of the transit system. |
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| (1228544) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by AEM-7AC #901 on Thu Jun 13 14:12:10 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Jersey Mike on Thu Jun 13 12:29:08 2013. relying on the operatorsExcept that transit agencies presume that their employees are a bunch of walking cokeheads. See modern day Boston Green Line. I'm amazed that they haven't put signals down there yet. OTOH, you can get away with certain things when you're a Stadtbahn... |
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| (1228560) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by randyo on Thu Jun 13 15:04:27 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by AEM-7AC #901 on Thu Jun 13 14:12:10 2013. The subway portion of the Green Line and the Riverside Line do have signals which the operators ignore constantly. |
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| (1228574) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by AEM-7AC #901 on Thu Jun 13 15:27:29 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by randyo on Thu Jun 13 15:04:27 2013. I probably should have said enforceable signals. :-) |
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| (1228639) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by merrick1 on Thu Jun 13 19:50:47 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Lou from Brooklyn on Thu Jun 13 08:04:10 2013. Set up the short turn terminals with a center pocket track. The train comes in, doors open on both sides, doors close on both sides and the train goes back in the opposite direction. No need to clear the train. |
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| (1228642) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Jsun21 on Thu Jun 13 20:13:35 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by merrick1 on Thu Jun 13 19:50:47 2013. And build that how, where and with what money? |
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| (1228673) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Sand Box John on Thu Jun 13 23:34:18 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by randyo on Thu Jun 13 13:47:34 2013. Just because trains are "scheduled" a certain way on paper (or on a computer) doesn't mean that it will show up that way in the real world. Variable such as passenger interference and other conditions impact on the on time performance of the transit system.It depends on how the subsystem within the Automatic Train Control system works. In WMATA's ATC system there is a subsystem called Automatic Train Supervision, this subsystem adjusts train speed to compensate for delays. That is why there are 3 speed readout on the operators console of a metrorail car. left readout civil speed limit, middle readout regulated speed limit, and right readout actual speed. The regulated speed limit is adjusted to maintain the even spacing of trains at junction and along the line. Mind you this only works when things don't get to jacked up. John in the sand box of Maryland's eastern shore. |
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| (1228683) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Jackson Park B Train on Fri Jun 14 00:11:14 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Jersey Mike on Thu Jun 13 12:29:08 2013. I was referring to the subway--State St in particular which from grade timers on the ramps down from the L to signals for the interlockings after rising up was fully signaled from the get go. You are correct that in the 50s when CTA ran far more service than at present there were no block occupancy signals on the elevated structure. |
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| (1228728) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by Jersey Mike on Fri Jun 14 09:34:53 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by AEM-7AC #901 on Thu Jun 13 15:27:29 2013. They can't run the service even with CBTC. Some sort of adaptive cruise control radar system as seen on high end luxury cars might actually work well. The ultimate result is going to be something that resembles an autonomous vehicle. Its EXACTLY the same problem...only easier cause its on rails. |
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| (1228743) | |
Re: CBTC + Short Turn Terminals = Affordable 40tph. |
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Posted by FYBklyn1959 on Fri Jun 14 11:10:13 2013, in response to Re: CBTC + Short Turn Terminals = Affordable 40tph., posted by Sand Box John on Thu Jun 13 23:34:18 2013. IIRC, BART has the same (or a similar) system. Except on the console (this was an "A" car), the readings were stacked (top to bottom, Civil, Regulated, Actual). I remember noticing that, during a trip through the TransBay Tube, the Civil was 80, but the regulated (and for most of the time, the actual) topped out at 68 mph. At the time, I was a bit annoyed by this, but now I understand that it was probably set that way to maintain headway. |
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