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SAS termini questions |
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Posted by stephenk on Fri Aug 12 16:41:34 2005 I have a few (well, more than a few) questions on the present proposals for the SAS.1) Will the Hanover Sq terminus have a bi-level island platform/scissors crossover arrangement, as at Whitehall St terminus on the SAS track map found on nycsubway.org (which I assume is not a track map of the current proposals)? Or will it be a normal island platform/scissors crossover arrangment (as at Times Square on the 7), or some other terminus arrangement? 2) Have the plans for connecting the North end of the SAS to the existing IRT network been abandoned, and why? Is the spur just before the line curves in 125th St designed for future connections to the IRT? Is it likely that the SAS could be extended (if it ever gets built in the first place) to run along 125th St and thus interconnect with all of the lines that cross 125th St? 3) Will the 125th St terminus have a normal island platform/scissors crossover arrangement? |
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Re: SAS termini questions |
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Posted by Alargule on Fri Aug 12 16:45:16 2005, in response to SAS termini questions, posted by stephenk on Fri Aug 12 16:41:34 2005. Quote:...(if it ever gets built in the first place)... That's all that's left to say about the SAS for now...:-( |
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Re: SAS termini questions |
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Posted by RonInBayside on Fri Aug 12 16:56:37 2005, in response to SAS termini questions, posted by stephenk on Fri Aug 12 16:41:34 2005. Details are on MTA's website. Click on MTA Capital Construction and follow the links. |
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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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Re: SAS termini questions |
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Posted by stephenk on Fri Aug 12 17:15:49 2005, in response to Re: SAS termini questions, posted by RonInBayside on Fri Aug 12 16:56:37 2005. "Details are on MTA's website. Click on MTA Capital Construction and follow the links."Thanks. I've already looked there, but I can't find the answer to most of my questions there. |
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Re: SAS termini questions |
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Posted by Alargule on Fri Aug 12 17:21:50 2005, in response to Re: SAS termini questions, posted by stephenk on Fri Aug 12 17:15:49 2005. Look harder. Most of your questions can be answered if you open the more technical pdf-files. Everything there is to know about the SAS, is there. |
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Re: SAS termini questions |
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Posted by stephenk on Fri Aug 12 17:34:34 2005, in response to Re: SAS termini questions, posted by Alargule on Fri Aug 12 17:21:50 2005. "Most of your questions can be answered if you open the more technical pdf-files"Thanks, there is more to those pdf's than what I thought! May take a few days to read............ |
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Re: SAS termini questions |
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Posted by Alargule on Fri Aug 12 17:35:40 2005, in response to Re: SAS termini questions, posted by stephenk on Fri Aug 12 17:34:34 2005. ...hmmm, maybe that's why the SAS has been delayed for so long...;-) |
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Re: SAS termini questions |
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Posted by RonInBayside on Fri Aug 12 17:43:02 2005, in response to Re: SAS termini questions, posted by Alargule on Fri Aug 12 17:35:40 2005. When the CIA asked Lockheed's Skunk Works to design the U-2 spy plane, Kelly Johnson's team did it in a matter of months.When the US US Air Force asked McDonnell Douglas to write a proposal for the F-15, McAir took years and then shipped the proposal to Washington in an 18-wheeler. You think the Air Force staff actually read all of that? Every page? |
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Re: SAS termini questions |
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Posted by Alargule on Fri Aug 12 17:45:48 2005, in response to Re: SAS termini questions, posted by RonInBayside on Fri Aug 12 17:43:02 2005. It was meant to be interpreted in an ironic way, my dearest friend, although I realise at the same time, that not everyone here is blessed with the capability to understand the aforementioned concept...:-) |
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Re: SAS termini questions |
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Posted by RonInBayside on Fri Aug 12 17:54:51 2005, in response to Re: SAS termini questions, posted by Alargule on Fri Aug 12 17:45:48 2005. Oh, I know what you meant. I just took the opportunity to poke fun at very long documents. |
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Re: SAS termini questions |
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Posted by Alargule on Fri Aug 12 17:56:09 2005, in response to Re: SAS termini questions, posted by RonInBayside on Fri Aug 12 17:54:51 2005. Very long documents are there to confuse the critics - and for extra employment of course (hey, somebody has to type them, right?). |
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Re: SAS termini questions |
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Posted by RonInBayside on Fri Aug 12 18:08:41 2005, in response to Re: SAS termini questions, posted by Alargule on Fri Aug 12 17:56:09 2005. Yes. And in the case of the F-15, somebody did type them. Word processing machines were still in our future in the late 1960s (or had the first Laniers already come out?) |
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Re: SAS termini questions |
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Posted by Charles G on Fri Aug 12 18:59:17 2005, in response to Re: SAS termini questions, posted by Alargule on Fri Aug 12 17:56:09 2005. One of the first rules of dealing with business regulation -- "When in doubt, inundate them with paper"... |
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Re: SAS termini questions |
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Posted by stephenk on Fri Aug 12 19:50:09 2005, in response to SAS termini questions, posted by stephenk on Fri Aug 12 16:41:34 2005. After being directed to the pdf's I thought I'd answer my own questions, just in case anyone else is the slightest bit interested.1)Will the Hanover Sq terminus have a bi-level island platform/scissors crossover arrangement, as at Whitehall St terminus on the SAS track map found on nycsubway.org (which I assume is not a track map of the current proposals)? No, it will be a 2 track, 1 island platform (most likely with scissors crossover) station that can handle 26tph. 2)Have the plans for connecting the North end of the SAS to the existing IRT network been abandoned, and why? Is the spur just before the line curves in 125th St designed for future connections to the IRT? Is it likely that the SAS could be extended (if it ever gets built in the first place) to run along 125th St and thus interconnect with all of the lines that cross 125th St? It looks like, if the SAS is built, that the tracks won't connect with the existing IRT network, however the spur tracks are designed for future connections. I can't find any evidence of extending the SAS along 125th St (I think its a good idea!) 3) Will the 125th St terminus have a normal island platform/scissors crossover arrangement? It will have a 3 track, 2 island platform layout that can handle 30tph. The overrun tracks will merge into 2 storage tracks. Trains will reverse in platforms. This though does pose a problem. The 3 tracks are needed for a reliable 30tph (although Hong Kong seems to be able to manage 30tph with 2 tracks and 600ft trains!). But having 3 tracks and 2 island platforms can seriously complicate passenger flow (which could potentially delay trains), as well as complicating crew stepping back operations. |
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Re: SAS termini questions |
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Posted by WMATAGMOAGH on Fri Aug 12 20:01:04 2005, in response to Re: SAS termini questions, posted by stephenk on Fri Aug 12 19:50:09 2005. Why would they want 30 TPH turnback capacity at one end but only 26 at the other?Also, there is little purpose in my view to connect the SAS to the A Division since it is to be a B Division line at this point. Unless it is going to give the mainline IRT lines some added flexibility, but inter-division connections already exist at Concourse and 207th Street Yards. |
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Re: SAS termini questions |
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Posted by stephenk on Fri Aug 12 20:07:17 2005, in response to Re: SAS termini questions, posted by WMATAGMOAGH on Fri Aug 12 20:01:04 2005. "Why would they want 30 TPH turnback capacity at one end but only 26 at the other?"Because the northern terminus is planned to turn 28tph (Q and T services), whilst the southern terminus is planned to turn just 14tph (T service). The Q will branch off below 72nd St station. |
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Re: SAS termini questions |
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Posted by Broadway Lion on Fri Aug 12 22:07:45 2005, in response to Re: SAS termini questions, posted by stephenk on Fri Aug 12 19:50:09 2005.  But having 3 tracks and 2 island platforms can seriously complicate passenger flow (which could potentially delay trains), as well as complicating crew stepping back operations. Probly turn (Q) on one platform and (T) on the other. 
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Re: SAS termini questions |
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Posted by SubwayNut on Sat Aug 13 00:43:40 2005, in response to SAS termini questions, posted by stephenk on Fri Aug 12 16:41:34 2005. F.Y.I. The official track maps are on the MTA's website, part of the FEIS: HereIts in two pdfs under Figures 2-4 and 2-5 |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 04:07:02 2005, in response to Re: SAS termini questions, posted by SubwayNut on Sat Aug 13 00:43:40 2005. Thanks, that's what I'd been looking for! |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 04:29:25 2005, in response to Re: SAS termini questions, posted by RonInBayside on Fri Aug 12 17:43:02 2005. When the US US Air Force asked McDonnell Douglas to write a proposal for the F-15, McAir took years and then shipped the proposal to Washington in an 18-wheeler.You think the Air Force staff actually read all of that? Every page? Of course not. They just read the summary on top - aka the Janet and John bit. Once they'd agreed to that, they're tied down to whatever someone's hidden on page 94 of Appendix K. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 04:33:02 2005, in response to Re: SAS termini questions, posted by SubwayNut on Sat Aug 13 00:43:40 2005. Fig 2-4 makes it look like the middle track at 125th St can be accessed from both directions, but trains can only leave to the west. If this is the case, it is a very strange track layout. |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 04:35:46 2005, in response to Re: SAS termini questions, posted by Broadway Lion on Fri Aug 12 22:07:45 2005. Probly turn (Q) on one platform and (T) on the other.That probably wouldn't work, particularly at 28tph. After viewing the track maps, the 125th St terminus will actually have 3 tracks, 1 island platform, and 1 side platform, as opposed to the layout that I thought it had in previous posts (3 tracks, 2 islands) From observations in London at 3 track termini (with track layouts that allow for the least possible conflicts to departing trains - 33%), the sequence of operation for the highest capacity is:- (With track 1 being the inbound side, and track 3 being the outbound side) Track 1 - train arrives (can occur simultaneously with next movement) Track 2 - train departs Track 2 - train arrives (can occur simultaneously with next movement) Track 3 - train departs Track 3 - train arrives (conflicts with next departure) Track 1 - train departs and so on. Thus, if this sequence was used at 125th St, then the services would probably operate in the following order:- Q train - track 1 T train - track 2 Q train - track 3 T train - track 1 Q train - track 2 T train - track 3 and back to the start. Thus for any passengers wanting a specific train (Q or T), who have just missed a train on tracks 1 or 2, they will have to go back up the steps and across to the other platform. This is very likely to cause delays and/or injuries caused by people running for the trains and obstructing the doors, so as to avoid having to do a platform change. It also means that crews stepping back wil often have to transfer platforms too. This is probably not a problem under normal running conditions, but if trains start running out of sequence for whatever reason, then careful management of stepping back operations would have to be implemented to make sure the correct crew are on the correct platform! |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 04:43:39 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 04:35:46 2005. As a (fairly infrequent) user of Morden station, I catch the first train, and then worry at Kennington about where I'm actually going. Maybe those at 125th St should take whatever comes first and transfer at 72nd St if necessary. |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 05:04:13 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 04:33:02 2005. "Fig 2-4 makes it look like the middle track at 125th St can be accessed from both directions, but trains can only leave to the west. If this is the case, it is a very strange track layout. "I noticed that as well. I guess it's just been drawn slighly wrongly. I would think that there is a large scissors crossover between the inbound and outbound tracks, and a smaller scissors crossover between the inbound and middle tracks. |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 05:09:24 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 04:43:39 2005. Actually, at Morden the trains presently only reverse in 2 of the 3 tracks. The 3rd track is used for trains entering or leaving service. This makes the stepping back operation simpler, as all reversing trains share an island platform. It also means that passengers don't have to swap islands if they miss a train.When the Northern line gets its planned capacity upgrade after CBTC is installed in 2011, then probably all 3 platforms will need to be used to reverse the proposed 35tph. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 07:20:36 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 05:09:24 2005. Actually, at Morden the trains presently only reverse in 2 of the 3 tracks. The 3rd track is used for trains entering or leaving service. This makes the stepping back operation simpler, as all reversing trains share an island platform. It also means that passengers don't have to swap islands if they miss a train.I'll have to go and see if they still open up trains on both sides on p3/4. I haven't been there for a couple of months. When the Northern line gets its planned capacity upgrade after CBTC is installed in 2011, then probably all 3 platforms will need to be used to reverse the proposed 35tph. Firstly, what's the idea behind it being 35tph? I'd've thought 36tph would have made headways much simpler. Even if all platforms were used to reverse this 35tph, the most efficient way would still have all boarding on p4/5: 1) Train arrives on p1/2. 2) Train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. 3) Train on p3/4 departs; train on track 45 moves onto p5; train arrives on p1/2. 4) Train on p5 departs; train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. (repeat stages 3 and 4) |
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Re: SAS termini questions |
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Posted by Broadway Lion on Sat Aug 13 10:02:05 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 04:35:46 2005.  Thus for any passengers wanting a specific train (Q or T), who have just missed a train on tracks 1 or 2, they will have to go back up the steps and across to the other platform. LION is not convinced. You assume an equal number of (Q) and (T) trains. This might not be the case. Maybe they run 2:1. Maybe they run 3:2. LION does not know. But then LION would not have designed a station like that. LION would have followed 125th Street to the Hudson River, and make there a two track LOOP.
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 10:59:35 2005, in response to Re: SAS termini questions, posted by Broadway Lion on Sat Aug 13 10:02:05 2005. "LION is not convinced. You assume an equal number of (Q) and (T) trains.This might not be the case. Maybe they run 2:1. Maybe they run 3:2. LION does not know. But then LION would not have designed a station like that. LION would have followed 125th Street to the Hudson River, and make there a two track LOOP." There are planned to be equal numbers of T and Q trains. 14tph each at peak times. I would agree with you on the loop. As the Paris metro has shown, non-passenger loops are a very good way of reversing lots of trains. Unfortunately they tend to cost a bit more to build too! |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 11:32:36 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 07:20:36 2005. "I'll have to go and see if they still open up trains on both sides on p3/4. I haven't been there for a couple of months"I think they still do, mainly for the benefit of arriving passengers although departing passengers are directed to platforms 4/5 (assuming everythings working as it should). "Firstly, what's the idea behind it being 35tph? I'd've thought 36tph would have made headways much simpler" I totally agree with you there. 35tph is an odd number. 34 or 36tph would be more sensible. As trains will be revesing in three platforms, then there will probably be uneven headways, as 33% movements conflict. Maybe this results in the 35tph? "Even if all platforms were used to reverse this 35tph, the most efficient way would still have all boarding on p4/5: 1) Train arrives on p1/2. 2) Train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. 3) Train on p3/4 departs; train on track 45 moves onto p5; train arrives on p1/2. 4) Train on p5 departs; train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. (repeat stages 3 and 4) " Some of the Paris metro termini with 3 tracks use a similar idea, with some trains relaying in sidings, and some trains reversing in a centre track in the station. It also helps with passenger flow as all passengers arrive on one island, and depart on the other. However, given LULs draconian tipping out rules, and the 4 minute driver end change rule, I think the above would get a bit too complicated to operate. Personally I think it would probably be easier to reverse trains in all three platforms, with drivers stepping back 3 trains (as will happen at Stratford on the Jubilee Line from next January). If Bank vs Charing X trains ran in a 2:1 ratio (as they do in the off-peak at present), that would be even better for stepping back operations. But using all 3 platforms would result in the passenger flow problems that I've mentioned earlier in this thread. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 13:59:48 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 11:32:36 2005. I totally agree with you there. 35tph is an odd number. 34 or 36tph would be more sensible. As trains will be revesing in three platforms, then there will probably be uneven headways, as 33% movements conflict. Maybe this results in the 35tph?Which would suggest a real capacity of 462/3tph - which is itself a strange number. "Even if all platforms were used to reverse this 35tph, the most efficient way would still have all boarding on p4/5: 1) Train arrives on p1/2. 2) Train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. 3) Train on p3/4 departs; train on track 45 moves onto p5; train arrives on p1/2. 4) Train on p5 departs; train arrives on p3/4; train on p1/2 moves beyond station to relay on track 45. (repeat stages 3 and 4) " Some of the Paris metro termini with 3 tracks use a similar idea, with some trains relaying in sidings, and some trains reversing in a centre track in the station. It also helps with passenger flow as all passengers arrive on one island, and depart on the other. However, given LULs draconian tipping out rules, and the 4 minute driver end change rule, I think the above would get a bit too complicated to operate. Stepping back would probably sort it. Drivers of the middle track trains would need to step back two intervals. Drivers of the trains relaying beyond the station would have to drive the train forward onto track 45, then walk from the south end of p5 to the north end of p2 to board the rear of another train to drive it back north out of track 45 and up the line. This would probably mean stepping back three intervals. With the number of staff hanging around stations, tipping out shouldn't be a problem. Maybe one member of platform staff should be transferred to Morden from each of KXSP and Euston. Personally I think it would probably be easier to reverse trains in all three platforms, with drivers stepping back 3 trains (as will happen at Stratford on the Jubilee Line from next January). I suspect that LU will actually implement something like that. It's more their kind of way of doing things. If Bank vs Charing X trains ran in a 2:1 ratio (as they do in the off-peak at present), that would be even better for stepping back operations. I really don't see it working at Camden Town like that with 35tph. Within a day, trains would be backed up to Leicester Square. The scheme of operations I'd want to see would be: 17tph Morden - Bank - Golder's Green 12tph Morden - Bank - Finchley Central (or East Finchley if they can sort out the layout) 5tph Morden - Bank - Mill Hill East 17tph Kennington - Charing X - Edgware 17tph Kennington - Charing X - High Barnet |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 14:09:21 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 10:59:35 2005. I would agree with you on the loop. As the Paris metro has shown, non-passenger loops are a very good way of reversing lots of trains. Unfortunately they tend to cost a bit more to build too!Maybe the MTA's (and TfL's) planners should be given all expenses paid trips to Paris, Madrid, Lille, and Munich. They'd learn a lot. |
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Re: SAS termini questions |
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Posted by WMATAGMOAGH on Sat Aug 13 14:15:49 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 14:09:21 2005. TFL has so many short turns and branches on many of its lines (but not all). Is terminal congestion that bad?New York doesn't seem to want loops, nor does it want short turns. That to me is problematic. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sat Aug 13 14:21:55 2005, in response to Re: SAS termini questions, posted by WMATAGMOAGH on Sat Aug 13 14:15:49 2005. TFL has so many short turns and branches on many of its lines (but not all). Is terminal congestion that bad?It can be, especially on the District Line. |
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Re: SAS termini questions |
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Posted by stephenk on Sat Aug 13 15:45:56 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 14:09:21 2005. "Maybe the MTA's (and TfL's) planners should be given all expenses paid trips to Paris, Madrid, Lille, and Munich. They'd learn a lot"Don't forget Moscow. Reversing 40tph with 160m long trains is bloody impressive! |
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Posted by Peter Rosa on Sat Aug 13 20:47:43 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 14:09:21 2005. Maybe the MTA's (and TfL's) planners should be given all expenses paid trips to Paris, Madrid, Lille, and Munich.I got a better idea. Let's send the MTA's planners and all its executives to, say, North Korea or Somalia. One-way. My LIRR/NYCT blog |
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sat Aug 13 21:17:38 2005, in response to Re: SAS termini questions, posted by stephenk on Sat Aug 13 15:45:56 2005. "Maybe the MTA's (and TfL's) planners should be given all expenses paid trips to Paris, Madrid, Lille, and Munich. They'd learn a lot"Don't forget Moscow. Reversing 40tph with 160m long trains is bloody impressive! The theory of designing terminals is well understood. It's just not practiced by the TA planners, car designers and TA operations. If the TA designed and ran terminals that could handle 40 tph like Moscow, then they would not need the SAS. They are currently operating 24 (loc) + 26 (exp) = 50 tph on the Lex. Operating 40 tph on each track would increase service levels by 60%. Trains that now have leave load levels of 1.2 would have leave load levels of 0.72. |
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sat Aug 13 21:25:12 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sat Aug 13 04:33:02 2005. You will note that the TA has followed the Jamaica Center design by placing the double scissor crossover for Hanover Sq. far from the platform. |
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Re: SAS termini questions |
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Posted by julie_profumo on Sat Aug 13 21:33:44 2005, in response to SAS termini questions, posted by stephenk on Fri Aug 12 16:41:34 2005. The questions are irrelevant. The odds of you, Julie, or anyone reading this living to see the Second Avenue Subways completion are slim to nil. s.to.she.who.am.the.only.one@gmail.com |
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Re: SAS termini questions |
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Posted by Terrapin Station on Sat Aug 13 22:48:38 2005, in response to Re: SAS termini questions, posted by julie_profumo on Sat Aug 13 21:33:44 2005. JULIE PROFUMO, America's Prettiest Trackworker!proff/pics? |
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Re: SAS termini questions |
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Posted by Rail Blue on Sun Aug 14 04:16:38 2005, in response to Re: SAS termini questions, posted by Stephen Bauman on Sat Aug 13 21:25:12 2005. And what's with those two extra tracks at 14th St, but still only one island platform? |
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Posted by stephenk on Sun Aug 14 06:27:56 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sun Aug 14 04:16:38 2005. "And what's with those two extra tracks at 14th St, but still only one island platform?"I think those extra tracks are for train stabling. Apparently the bedrock there is suitable for building extra tunnels fairly easily. |
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Re: SAS termini questions |
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Posted by SUBWAYMAN on Sun Aug 14 06:33:16 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sun Aug 14 04:16:38 2005. I think those are layup tracks. |
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Re: SAS termini questions |
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Posted by stephenk on Sun Aug 14 06:33:20 2005, in response to Re: SAS termini questions, posted by Stephen Bauman on Sat Aug 13 21:25:12 2005. "You will note that the TA has followed the Jamaica Center design by placing the double scissor crossover for Hanover Sq. far from the platform."It's a bit odd isn't it. I think MTA need a few lessons in terminus design! If Hong Kong MTR can design spacious island platform/2track/scissors crossover termini which can handle 34tph (although in reality they run 28.5-30tph), then I don't understand why MTA can't design something similar. |
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Re: SAS termini questions |
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Posted by stephenk on Sun Aug 14 06:38:10 2005, in response to Re: SAS termini questions, posted by Stephen Bauman on Sat Aug 13 21:17:38 2005. "They are currently operating 24 (loc) + 26 (exp) = 50 tph on the Lex. Operating 40 tph on each track would increase service levels by 60%. Trains that now have leave load levels of 1.2 would have leave load levels of 0.72."But is the Lex's reversing capacity is its major contraint? I would have thought that excessive station dwell time would be its capacity limiter? |
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sun Aug 14 07:23:54 2005, in response to Re: SAS termini questions, posted by stephenk on Sun Aug 14 06:38:10 2005. But is the Lex's reversing capacity is its major contraint?Hardly. The Lex has a reversing terminal that handles only 2 trains during the am rush hour (South Ferry). The Brooklyn terminals (Flatbush and Utica) plus Rogers Jct limit additional express service. There are some routing changes that could increase express service in Brooklyn. I would have thought that excessive station dwell time would be its capacity limiter? It's pretty difficult to evaluate station dwell time on the Lex because service is so irregular. However, the theory is a no brainer. The amount of dwell time is related to the number of people trying to cross the door threshold. The more people the greater the dwell time; fewer people then less dwell time. The total number of people crossing the door threshold during the entire rush hour is relatively constant with respect to the number of trains. However, the number of people crossing the door threshold for each individual train is related to the number of trains. Want to decrease dwell time? Add more trains. Track geometry does limit the Lex express capacity to slightly less than 40 tph. The problem is the express-local junction south of 125th St. They might be able to fix it by redesigning the signals. However, there's no rush because that junction limits the tph to the high 30's and they are currenly operating only 26 tph. The TA's principal impediment to increasing rush hour service levels is cost. In order to increase service during the 2 hour long rush hour period, the TA must pay an additional 16 man-hours for each train added. Each additional train for both the am and pm rush hours costs an additional 32 man-hours. The cost of increasing rush hour services levels by 20% (to previously operated levels) is just too high. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sun Aug 14 07:25:21 2005, in response to Re: SAS termini questions, posted by stephenk on Sun Aug 14 06:33:20 2005. And IIRC Brixton (London, Vic) was designed for something crazy like 42tph. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sun Aug 14 07:26:38 2005, in response to Re: SAS termini questions, posted by Stephen Bauman on Sun Aug 14 07:23:54 2005. The TA's principal impediment to increasing rush hour service levels is cost. In order to increase service during the 2 hour long rush hour period, the TA must pay an additional 16 man-hours for each train added. Each additional train for both the am and pm rush hours costs an additional 32 man-hours. The cost of increasing rush hour services levels by 20% (to previously operated levels) is just too high.This is why I included Lille on my list of places to visit. ;-) |
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sun Aug 14 07:34:37 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sun Aug 14 07:26:38 2005. This is why I included Lille on my list of places to visit.JFK is closer for ZPTO. There is another solution that does not require completely redesigning the system. Part timers. |
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Re: SAS termini questions |
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Posted by Rail Blue on Sun Aug 14 07:43:08 2005, in response to Re: SAS termini questions, posted by Stephen Bauman on Sun Aug 14 07:34:37 2005. "This is why I included Lille on my list of places to visit."JFK is closer for ZPTO. But Lille is a city with a serious rush hour operation - it regularly operates at over 40tph. The relentless efficiency of the am rush is simply impressive. There is another solution that does not require completely redesigning the system. Part timers. Agreed, but why not make the SAS self-contained and automated (should it ever happen)? |
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Re: SAS termini questions |
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Posted by Stephen Bauman on Sun Aug 14 08:15:37 2005, in response to Re: SAS termini questions, posted by Rail Blue on Sun Aug 14 07:43:08 2005. why not make the SAS self-contained and automated (should it ever happen)?The challenge for NYC should be to utilize the capacity that already exists. They are not doing a very good job of that. |
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