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Union Tpke

Why Your Subway Train Might Start Moving Faster

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20 minutes ago, Union Tpke said:

I might as well share the paper I did on subway signaling this past summer while I was working at the Rudin Center for Mitchell Moss.

https://docs.google.com/document/d/1XsQUrRs4_Xeq0iuh_pIRj7aTBLCrBMd2KQQdEbRs_WE/edit#heading=h.164ffnaqwv1t

I need to update it with the findings from the recent study. Please let me know if you have any questions. Also, some credit should go to @RR503 for helping me with it.

I was not expecting much from the Speed and Capacity study, but was very excited upon reading it. It vindicates Save Safe Seconds, and provides other useful suggestions. I really love the descriptions and diagrams used to explain the signal system, especially the ones for ST.

Here are my takeaways from the study:

- Recommendations

 

  • Issues that @RR503 have been raising for some time
    • Automatic routing function is disabled for intermediate terminals like East 180th Street due to the complexity of moves and the possible of trains entering dark territory 
      ARS in many places 'shoots' based on the schedule and once a route is called signals would have to run time to be set for the correct train or to allow drill moves or out of sequence trains. So locations with big time variances are typically shut down in ARS implementations.
       
    • Suggest that this should be reevaluated for straight routes and standard moves for 2 and 5 trains
      See above, the reevaluation might reveal more usable timeframes, there may be a benefit to putting ARS online during rush hour, but this is also the timeframe with the biggest risk of variance, with the lowest amount of tolerance and the highest adverse impact.
       
  • Other interesting findings
    •  NYCT practice of posting limits at V4 level since passengers might be subjected to uncomfortable conditions; T/Os overcompensate by running much lower than V4 to avoid being written up
      Some of this likely has to do with the maintenance status of the equipment, old clapped out trains with old clapped out suspensions will not tolerate the posted speed as well as the numbers in the spreadsheet say. I know on the Railroad there are definitely speeds and switches that are signed for a certain speed and I've almost been thrown out my seat at the posted speed. If a lot of people are doing it, there's a good chance a lot of people aren't crazy.
    • Posted speeds via lunar lights often washed out and hard to read; small and posted right at signals-hard to read
      That's probably an improvement, signs often seem to disappear or are never installed, or the GT sign where you're supposed to hit the speed doesn't come into view until after a blind curve. As is typical, most signs are installed on an inscrutable guideline that resists criticism from people on the ground and 'you should know your route' anyway. (Even if you bounce around on the extra list or don't encounter a certain signal sequence because of the hours you work), that attitude has historically limited the amount of resources in railroading culture in general.
  • Provides great methodology of how Save Safe Seconds has been done
    •  Increasing speed through switches-some allow up to 25 mph, signing them-all limiting speeds are lack of signs 
      No sign is 10mph, IIRC. In the dark ages TOs probably knew what they could get away with sign or no sign. But in the age of black boxes, even recorders and people 'in the bush' with radar guns, these inconsistencies start to show, and start to hurt.
  • Interesting recommendations
    • More frequent verification of train speedometers
      Good luck, part of the problem is flat wheels and leaf season creating damage in the wheels which has to be trued (making the wheel smaller, causing more inter and intra consist variance making a consistent operation even between opposite ends of the consist difficult).
    • 149th implementation of modern axle counters to reduce the time it takes to release switches between route changes by verifying than an approaching train is stopped at the station Not sure what method they will use to prove the train is stopped but whatever works, other countries like Germany use cameras and manual overlap releases on their DR S 60 panels, that would require Transit to have faith in their employees, no danger of that.
    •  Replace signs with high reflectivity, or just cleaning existing signs more regularly, or adding illumination (small lunar LED) One thing I found effective was plates with holes and a reflective surface behind which creates the message, fairly resistant to dirt.
    • Advance warning signs (25 MPH ahead)-areas visibility an issue or a major speed change is needed Pretty simple and standard in many places around the world and even the country.
    • Could work in conjunction with, the countdown timers NYCT has recently been installing for GT signals (which have been reportedly difficult to see from a distance).
    • Consider modify circuits to flash light while ST/GT running
    •  If a solid-state device with a variable flash rate could be used, increasing the rate as timer gets closer to expiring may be considered, also dwell timers
    • Not all ST signals have lunar indications that let know that ST is running, T/Os assume lower speeds, even if not required, longer-term effort Noticed that when I was a kid, doubt no one else in NYCT did, I guess it's been ignored all this time.
    • Adding these indications would be of very significant benefit for the time and cost involved” 
      Only took 85 years.
    • Revised signal standards on lines that will use block signaling for areas not included in the next two capital programs
    • Examination of potential for reducing run times on express track and branches by assigning higher performance car fleets
      Typically the NYCT has assigned the laziest performing trains to Express lines to mitigate the damage, with the Hippos (R68s) as lackluster as they've ever been and the R44s getting minimal TLC before they become barnacles where will the 'low performance car fleets' go
    • NYCT has identified R68 fleet acceleration as well below the acceleration design criteria limit and can be increased with exceeding the limits of the existing signal system-NYCT has already begun engineering effort required to improve R68 acceleration
      It is amazing how a study can reveal things that have been obvious since the early 90s.
  • Interesting historical info
    •   All signal projects since 1988 have been subject to approval of the Speed Policy Committee
    • “The Speed Policy Committee performed a test of V4 and V6 speeds on the White Plains Road (Subdivision A) line in 1994 on curves north of Simpson Street and north of Bronx Park East. Results revealed that V6 is acceptable for GT signal settings but a V4 is more appropriate for passenger comfort and that V11 would be the Maximum Allowable Transient Speed) (MATS) of a train on a curve.”
    •    1994 Speed Policy
      • Recommended revisions to the speed parameters with the intent on eliminating unwarranted speed limits, decreased track/signal maintenance costs, maximizing passenger costs


        Having seen some of the evaluations I've always been astonished with the ease which it would be written 'no impact to service' even with a litany of speed reductions. My impression was that each action was only evaluated at an individual level, in aggregate of course 0.1 minutes * 20 is a lote on transit scales.
  • Scheduling
    • Schedule timetables could be adjusted to provide additional distance between these trains in both directions at Nostrand
    • Consider aligning 2 Line and 4 Line schedules to meet at 149th-align open spots on main lines, potentially allow 5 trains to move between two lines.
      • Why isn't this done now? @RR503
    • Correspondence of scheduled timetable to auto routing triggers for the 5 Line should be examined and possibly updated to ensure movements as efficiently as possible
  • Field shunting (Thank you Jose Martinez for bringing this story to the public!)
    • Examine potential benefits of removing shunting and restoring performance R68 fleets-N express between 59th Street and Atlantic-savings of 20 seconds per station stop (high end)
    • However, even with a smaller per-stop travel time savings, the total savings when accumulated over the entire route may be substantial."
      This reads like a vague open ended sentence that gets tagged into a report which can be interpreted a number of ways depending on the fallout/success

       
    • Do not know ether average performance of vehicles has not further degraded due to wear since 1997
      I'd say this is fairly inevitable there's no evidence that parts are freshly replaced.
    • Improving acceleration performance of the R46 fleet is not expected to be feasible or worthwhile. These 40+ year old cars are nearing the end of their life. While motors and the propulsion system can probably be replaced, the cost would be expected to be a substantial fraction of purchasing new vehicles.
  • Axle counters
    • Alternative to modifying existing track circuits-used to enhance fixed-block functionality can be used by CBTC
    • Switches at 149th are forced and locked in the normal position to allow trains to safely approach the station at higher speeds
    • ASR timer limits releasing of interlocking switches after a route was cancelled to prevent a train that is moving towards the interlocking and unable to stop from having a switch thrown underneath it-currently timer set to AREMA minimum value of 30 seconds
    • Axle counter would verify when southbound trains on Track 1 are berthed at platform, allowing a bypass of timer and a safe early switch release The axle counter can prove the train has entered the station, but unless something at the leaving end times that the train to a stop, I don't know how it functions to save time. Even if 40 axles pass counter A, the counter at B will read 0 until a train over runs the station at which point it would be too late. 
    • Eliminate the need for trains to extend dwell times Through what method do they expect to impact dwell time, unless this applies to 149th St and other stations with swinging overlaps specifically.
    • As timing circuit for shorting out approach/time locking elements before interlocking switches-much shorter length than typical 40 seconds required
    • Axle counters would act as a timing circuit for clearing of ST and GT signals, more predictable equipment circuit delay, not susceptible to loss-of-shunt delays, less reliance on average speeds; might allow for control line cutbacks due to reduce runaway speed values for MAS calculations
    • This is the concept behind Wheel Detectors, which last I checked did not fair well, any indication on how the situation is improved?
    • Subdivision of long track circuits to allow for control line cutbacks, allowing trains to move closer together where needed.
  • Things I had not realized
    • Only blocks deemed critical were modified for 135%
    • Key-by signals provide 110%
    • The benefits of using axle counters
  • Questions that remain
    • Why does it say a Maximum Attainable Speed of 50 mph?  "On tangent track and in some large radius curves, in the absence of any other speed restriction, the Average Normal Operating Speed is the highest speed that will allow service braking to limit the High Normal Operating Speed to 50 mph without experiencing Emergency" It states that 55 is the "Not-To-Exceed (NTE) Safe Speed".
    • Is it me, or doesn't this report discount the issue with speedometers? They are way out of whack on the R62/As and 68/As. T/Os on here have often mentioned readings of 70 mph while a train is stopped in a station.
    • What was the report referring to when it said there were options to modify car performance to 71% or 100% field strength?
    • Why hasn't the ATS system been updated since its implementation?
    • I don't know enough about the trigger system with ATS. Could this be elaborated on?
    • Could the automatic route function of ATS be elaborated on? What other areas could use the change?
    • -"Finding task force- 25 mph, can support moving at 27, so posted speeds do not need to change at all" This is something you have mentioned in the past @RR503 . Why not let the T/O know that they have 2 mph to spare? Pure speculation but the C-B-A of creating relatively uncommon signs which are within the margin of variance; and if the area is bracketed by other speed changes general practice would just be to energy manage what you already have.

 

 

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Posted (edited)

To the best of my knowledge, the following is the history of the braking/signals issue. Fair warning: this will be long

The design of signal systems is a project that requires consideration of many variables. At what rate does your equipment accelerate? At what rate does it brake? What assumptions can we make about train operator performance? About switches? Etc. The root cause of the timer/control line extension problem is that NYCT did not stick to or retroactively apply consistent standards for all of these variables, which in turn caused degradation in the safety provided by the signal system  (this is also basically the tl;dr of this post). 

In the oldest bits of the subway's signal system, safety was programmed around first-gen IND and BMT equipment -- your Standards, R1s and the like. As you all know now, acceleration performance was not governed to the performance of these older cars, and over time, the safety provided by the signal system was degraded. For example, while the R1 had a starting acceleration of 1.75mphps and a braking standard of 30 to 0 in 230 feet, the R10 (and all succeeding car classes, up to the R188) had starting accelerations of 2.5 and a 30mph braking distance of 250 feet. These changes alone ate into the level of safety provided by the signal system. Per the presentation I linked, this first round of non-compliance reduced signal safety by 20-35% depending on the location. To the point of actual danger in this stage of the problem's development, I am not aware of any crashes caused by control line deficiencies alone pre-1995, but given the spottiness of accident reporting and the difficulty of finding information on causes of the accidents which were reported, I would be wholly unsurprised if there had been a few.

NYCT recognized the safety issues that train/signal performance mismatches created as meriting action as early as 1980, when a capital plan report enumerated replacement of legacy signalling to bring the system in line with modern standards as being a key priority for the future. However, aside from the use of updated signal design standards in the replacement of legacy signalling, little retroactive work was done to fix these issues. Then, of course, the braking debacle happened. 

The general outline of the history that @Amtrak706's linked SubChat post lays out is essentially correct. During the changeover from cast iron to composition brake shoes, the braking effort of trains was significantly reduced. Depending on who you ask, that reduction of braking effort was either inadvertent and unknown, understood but thought of as acceptable, or indeed was a sought-after change. Short of finding the people/documents that surrounded this decision, there is no way of knowing in absolute, though I tend to believe this degradation was caused by gross oversight, given that the IG report documents many basic safety analysis failures in that era (ex: nobody thought to check whether giving R32s 115hp motors was a good idea from a safety perspective). Intent aside, the braking effort reduction all but compromised signal system safety -- per the IG report, adoption of the degraded brake standard would have put fully half of the system's signals in non-compliance. This issue was known in well advance of the Williamsburg Bridge accident, but (in another demonstration of the unanalytical trust in the signal system) was deemed a tolerable risk, as the brake system degradation was thought to be within the signal system's safety margin -- something only true where margin hadn't been consumed by acceleration changes. 

We arrive at the WillyB disaster. The signal system on the bridge was designed around legacy car capabilities; the fated signal, J1-128, was designed assuming the maximum attainable speed of a train passing it was 27.9 miles per hour, and thus provided 270 feet of stopping distance beyond it. But of course, both dimensions of performance changed that morning. The MAS of equipment of 1995 passing that signal was in the 34-36 miles per hour range, and the braking systems attached to that speedy equipment were weaker thanks to the R10-era downgrade and the composition related performance problems. How much weaker? The accident train passed J1-128 somewhere around 34 miles per hour, and likely impacted the (brownM) ahead of it at 18mph. That (brownM) was 288 feet from the trip arm of J1-128. So, change in velocity is 16mph, change in distance is 288 feet, area gradient is ~flat (see below diagram; impact occurred on a 2.25% upgrade, but that upgrade begins between 128 and impact, so even at the point of impact only about half of the train was on an upgrade which for our purposes can be equated with being flat). Plugging these values into our handy kinematics equations (after some unit conversions) yields a deceleration value of -2.1 mphps, or well below the specified -3.0, and the specified-from-30mph-accounting-for-various-confounding-factors average of -2.6. While poor braking undoubtedly played a role here, it is important to examine the counterfactual, or what would have happened if the train had performed per specification. Assuming a starting speed of 34mph and deceleration per the braking curve in the STV report (the one linked just 2 sentences ago), the train would still have needed >>270 feet to stop -- on flat rail it'd be ~330 feet, but at that point the gradient effect would be nontrivial. It would have collided with the (brownM) at a lower speed, to be sure, but the signal system was still fundamentally unsafe. 

Diagram, as promised (h/t @RailRunRob); for how to read see here, and don't miss the note about all control lines being two-block control unless otherwise shown.

D6QAKfQ.jpg

These deficiencies in deceleration and excess in acceleration were the study of a number of reports around the time of the Williamsburg Bridge disaster, some of which were summarized in the two documents I provided (this is what I was referencing when talking about risk analyses with normal brakes btw @Amtrak706). Again, as shown below, even with good brakes, a significant portion of the system's signals were out of compliance with car performance. Here's the slide on the West End line before its late 90s resignalling -- "improved braking" means restoration of the 30mph/250' standard. The preponderance of locations where sub-100% safety was provided was the major motivator behind the 1995-present signal mod effort; it became adopted policy to rectify all of these deficiencies (a list, mind you, that grew with time) to at least a >100% safety level. 

62cMTCK.png

(For more on this subject, see the discussion towards the end of the MTAIG report, as well as the latter third of the powerpoint.)

You think this post is done, right? Lol no. There's the equally important issue of standards to cover; I will attempt to be more brief here ;).

Just as train performance has changed over time, assumptions about train operator performance have changed over time. The two biggest changes therein were assuming trains went full speed through stations and that trains didn't comply with posted speeds. As I'm sure I've mentioned before, the original 1960s signal design for the Grand Central area on Lex did not enforce any curve speeds with timers -- signs only. Timers were only installed in the '70s, IINM. It goes without saying, but relying on signs alone to slow express trains approaching GC in excess of 40mph to speeds in the 15-20mph range for those curves is not something that would be even remotely permissible today, and indeed has been the driving force behind many GT adds. 

The assumption of 15mph exit speeds equally had impacts on signal design. If you browse through the IND signal prints on nycsubway.org, you'll notice that leaving signals always have two block control and provide little stopping distance beyond the second signal. You'll also notice that in-platform ST signals with cutbacks that reach beyond the platform (see, for example, on the 34 St print, signal B1-1035) provide precious little stopping distance beyond the end-of-platform-signal that would be the tripping signal (for 1035, that'd be B1-1031) if a train were to clear the ST cutback -- the dotted portion of the control line -- with a train stopped in the dotted portion. We no longer assume that trains slow at stations; the clearest manifestation of this change are the one shot GTs at the leaving ends of stations on lines like Pelham and West End. This assumption, too, has required modifications to the signal system, and has, along with the assumption of non-compliance with posted limits, driven the installation of DGTs at stations like Roosevelt Ave and Forest Hills where switches placed at the leaving end of the platform would have, under the assumption of 15mph leaving speeds, not required any enforcement. 

Other sorts of signal mods do exist, but the above cover the driving forces behind most of them: control line safety and train operator performance standards. Please correct me if you see mistakes in this.

In closing, I want to _strongly_ emphasize that all the above should not be seen as an unqualified defense of NYCT's mod effort. Cheapness in mod design (subbing one shots for two shots, doing one shots instead of control line extensions and ST cutbacks, refusing to cut in additional signals or insulated joints to mitigate mod impacts, etc) massively worsened the impact of said mods, contributing to the runtime and capacity losses that have driven the system to where it is today, and lagging signal system replacement timelines have increased the impact of mod campaigns simply because there exist many portions of track where signal systems (and accompanying mods) that should have been retired ages ago are still in service. Operational rot of other sorts has increased the impact of mods beyond design. NYCT's well documented discipline culture and maintenance disorganization has frightened TOs into taking timers well below their posted speeds, while overlong dwell times, overly complex service patterns, poor terminal operation and flagging rules have aggravated the impacts of mods on system capacity and performance in other ways. None of these aggravating factors should be at all minimized, as an agency that emphasizes the negative impact of a 2 shot GT30 but simply accepts 75 second dwell times is an agency failing to see the full operational picture, as it were. I could write posts of equal (if not longer) length on these other ops issues, but I daresay this is enough for tonight.

Edited by RR503
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Stupid question but:

I'm seeing a lot of mentions of R68 acceleration in the last few pages of this thread. Where can I find the report that discusses this?

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Posted (edited)

@RR503 Awesome writeup, thanks! I do have a couple nitpicks, though - I am pretty sure the horsepower increase during GOH on the 60’ SMEEs was to offset the weight of added equipment like AC, and that the cars’ performance was more or less the same as pre-GOH. Also, the NTSB found that if the striking (J) train had compliant brakes providing 3.0 mphps deceleration, it would have stopped 48 feet short of impact, as @Union Tpke stated.

Edited by Amtrak706
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Posted (edited)
7 hours ago, Union Tpke said:

What was the report referring to when it said there were options to modify car performance to 71% or 100% field strength?

 

My turn for a dissertation, lol. I’ll try to keep this as succinct as possible though.

Field “shunting” or “weakening” refers to the use of a resistive load placed in a circuit with the DC traction motors. This is done in order to more finely control the field strength through the motors at slower speeds, and to allow the motors to exceed their “balancing speed” (more on these uses in a bit). The resistive load is provided by resistor banks that hang beneath the car.

A mechanical cam unit controls the propulsion system by advancing through several stages that progressively increase the motors‘ field strength. From a dead stop, the first few stages place the motors in series, and resistor banks are connected in series to further weaken the field strength and keep acceleration at about 2.5mph/s. As the car picks up speed, these resistor banks are progressively dropped out from the circuit until full series is reached.

The cam then advances to parallel until the “balancing speed” is reached. This is when the electromagnetic force put out by the motor matches the back-electromagnetic force, or back-EMF, acting on the motor as a function of its rotational velocity. To overcome this, a shunt field is applied to the motor (a parallel resistive load that increases the required current through the motor at a given voltage). Field shunting can also be used to avoid commutator flashover caused by excessively high voltage, instead increasing current to provide more power.

IIRC the propulsion mods in 1996 only disabled the last stage(s) of field shunting, restricting the motors to less than 100% of maximum attainable field strength with full field shunting available (not aware of the exact numbers, although it’s probably less than 71% given that was one of the suggested values to which the fields strength could be increased). If I am correct about the mods only affecting the last stages, reverting the cars to full or increased field strength should just be a modification of the cam and shunt coils.

The DC cars also had a switch somewhere in the cab marked “exp/local” or “energy conservation” that when turned on would restrict the cam to enable or disable field shunting completely. I am pretty sure these switches are still in place on all cars except the ex-Corona R62As, on which they have been repurposed to control the side rollsign express/local LEDs. Of course, the cars can still be restored to full field strength - the T/O would just not be able to turn it off. This probably wouldn’t be an issue though, as prior to 1996 the switches would mostly be left on at all times.

One last thing to clear up any confusion about series/parallel and the master controller. The second and third notches are referred to as series and parallel - not because they directly move the cam to series or parallel, but because they STOP the progression of the cam at series or parallel. If the T/O wraps the controller around to full parallel from a dead stop, the cam will still advance through each stage of series and resistor banks. There is no reason to take off at series position on the controller and then advance to parallel, as the cam will do this regardless, and will do it smoother than the T/O could anyway. The exp/local or energy conservation switch was essentially a cheap TA attempt at a fourth controller notch, as its position on/off would either stop the cam at parallel or allow it to advance to full field shunting. And finally, the first notch on the controller is often called “shunt” (referring to its use for a slow-speed shunting move in the yard, not field shunting). This notch stops the advancement of the cam before full series, keeping some resistor banks cut in. That is why T/Os are told not to stay in this notch, as leaving the resistor banks cut in could burn them out.

Congrats if you read this whole thing - now get ready to have it all be completely irrelevant in 10-15 years once the fleet is fully AC propulsion. Lol...

Edited by Amtrak706
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Posted (edited)
5 hours ago, Amtrak706 said:

I do have a couple nitpicks, though - I am pretty sure the horsepower increase during GOH on the 60’ SMEEs was to offset the weight of added equipment like AC, and that the cars’ performance was more or less the same as pre-GOH.

I don't doubt that performance was _similar_, but the lack of any review to determine a) whether that was the case and b) if it wasn't, what the safety impacts would be is concerning. My point was much more about procedure than actual risk.

5 hours ago, Amtrak706 said:

Also, the NTSB found that if the striking (J) train had compliant brakes providing 3.0 mphps deceleration, it would have stopped 48 feet short of impact, as @Union Tpke stated.

Page? Document isn't searchable so I can't say authoritatively, but the as far as I can tell the NTSB's tests and test results demonstrated both that the brakes were deficient and that a collision would have occurred if the brakes were not deficient, IINM.

At any rate, car stopping distances at an arbitrarily assigned brake rate are not the metric we should use for evaluating safety, instead we should compare against the braking distance standard that existed before the collision, in other words NYCT's car performance safety minima for pre-brake degradation trains. I did this in my above post, but realize I spent very little time explaining what standard I was using, why, etc -- my apologies. As it so happens, the braking standard in effect for cars from 1948 to 1995 is the one we have today, and thanks to the STV report, we know that it requires a maximum braking distance from 35mph of 332 feet on flat rail. A 2.25% gradient over part of the run would shorten that distance, but not by >52 feet: from a starting speed of 34-36mph, the signals on the bridge were by NYCT's own guidelines incapable of protecting a train at MAS. 

Here's the braking standard used back then, which is the same as is used now.

lB84eFx.png

 

Also @Amtrak706, great post on field shunting! The acceleration mod made in 1996 was indeed to 100% field strength.

Edited by RR503
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11 hours ago, RestrictOnTheHanger said:

@RR503 have any of the STs at Roosevelt been fixed or modified? (E) and (F) trains seem to be moving better in that area during the AM rush recently.

No speed changes, though perhaps they recalibrated them... 

I'd be curious to know whether the speedup have a discernable startpoint, though. What I've noticed is that rushes on corridors like the Lex and QB will go okay enough until some train overdwells/is too timid with STs, at which point everything goes to hell. It's possible that as crews got moved around during the pick, the crew least comfortable with those conditions got moved around in the rush. 

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On 1/5/2020 at 8:38 PM, Union Tpke said:

Consider aligning 2 Line and 4 Line schedules to meet at 149th-align open spots on main lines, potentially allow 5 trains to move between two lines.

  • Why isn't this done now? @RR503

 

Question is why isn’t this done on all overnight service?

Makes no sense to have (4) and (6), (1) and (2), and (N) and (Q) show up within 3 minutes of each other during 16-20 minute headways overnight instead of every 8-10 minutes.

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On 1/10/2020 at 9:25 PM, Deucey said:

Question is why isn’t this done on all overnight service?

Makes no sense to have (4) and (6), (1) and (2), and (N) and (Q) show up within 3 minutes of each other during 16-20 minute headways overnight instead of every 8-10 minutes.

I've wondered that as well. Though, over night track work would probably negate any scheduled combined headway.

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On 1/10/2020 at 9:25 PM, Deucey said:

Question is why isn’t this done on all overnight service?

Makes no sense to have (4) and (6), (1) and (2), and (N) and (Q) show up within 3 minutes of each other during 16-20 minute headways overnight instead of every 8-10 minutes.

Assumed transfers most likely, if you had to get from 215th St to Nevins, would you rather take the (1) wait 3 minutes on the transfer or 8-10 minutes on the transfer.

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36 minutes ago, Jsunflyguy said:

Assumed transfers most likely, if you had to get from 215th St to Nevins, would you rather take the (1) wait 3 minutes on the transfer or 8-10 minutes on the transfer.

But that still creates a gross imbalance.

Consider the night (2) and (4) in Brooklyn. If both routes arrive as scheduled, the (4) gets a two-minute lead on the (2). This results in an 18-minute period of nothing, which serves to complicate both general trip planning and especially transfers involving this unfavorable gap (people between New Lots Avenue and Franklin Avenue can easily transfer to the (2), but Nostrand Avenue patrons must either take their chances with a bus or wait for a ridiculously long time for the (4), which is only exacerbated by the (5) being cut back to a Bronx shuttle if it runs at all, as well as the (6) being just out of reach.)

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On 1/10/2020 at 9:25 PM, Deucey said:

Question is why isn’t this done on all overnight service?

Makes no sense to have (4) and (6), (1) and (2), and (N) and (Q) show up within 3 minutes of each other during 16-20 minute headways overnight instead of every 8-10 minutes.

The base schedules on Lex and IRT West align (2) and (4) for a cross platform at Nevins and then interpolate the (1) and (6) to provide an even enough 9/11/9/11/9/11 pattern on the trunk portions of those routes, as intra-corridor ridership is high and transfer flows between trains aren't strong enough for the agency to prioritize a connection for one direction (ie giving (1) => (2) xfer riders a 3 minute wait would mean giving (2) => (1) riders a 17 minute wait). The (N) and (Q) take sufficiently different routes that the calculus is different for them -- they run a 6/14/6/14 iinm. 

Worth noting that these are _base_ schedules. Supplements frequently throw this all out the window. 

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43 minutes ago, RR503 said:

The base schedules on Lex and IRT West align (2) and (4) for a cross platform at Nevins and then interpolate the (1) and (6) to provide an even enough 9/11/9/11/9/11 pattern on the trunk portions of those routes, as intra-corridor ridership is high and transfer flows between trains aren't strong enough for the agency to prioritize a connection for one direction (ie giving (1) => (2) xfer riders a 3 minute wait would mean giving (2) => (1) riders a 17 minute wait). The (N) and (Q) take sufficiently different routes that the calculus is different for them -- they run a 6/14/6/14 iinm. 

Worth noting that these are _base_ schedules. Supplements frequently throw this all out the window. 

That's basically what I was taught years ago.  I was working at Lenox years ago and the TD, the TW/O, and the CTO sat me down at the model board and explained that way of thinking. At that board one could see a s/b train entering 149-3rd in the Bronx which meant the Lenox-135th shuttle could leave the terminal and make the relay move at 135th middle and not block the s/b (2) . If things were normal I would ride the shuttle,  switch to the (2) at 135 st and transfer to my New Lots bound (4) at Nevins. BTW  the (2) was Express in Manhattan back then and we would catch a (1) somewhere between Times Square and Chambers. As you pointed out with the (1) and the (2) running local together there's really no way to space them and keep that important connection at Nevins St. Back then the (4) also had an important connection at 125th and Lexington because the s/b (6) terminated there late nights with the (4) running local all the way to New Lots. You nailed it.  Carry on. 

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1 hour ago, RR503 said:

The base schedules on Lex and IRT West align (2) and (4) for a cross platform at Nevins and then interpolate the (1) and (6) to provide an even enough 9/11/9/11/9/11 pattern on the trunk portions of those routes, as intra-corridor ridership is high and transfer flows between trains aren't strong enough for the agency to prioritize a connection for one direction (ie giving (1) => (2) xfer riders a 3 minute wait would mean giving (2) => (1) riders a 17 minute wait). The (N) and (Q) take sufficiently different routes that the calculus is different for them -- they run a 6/14/6/14 iinm. 

Worth noting that these are _base_ schedules. Supplements frequently throw this all out the window. 

I guess my issue is “safety” - if (1) comes right after (2) overnight, there’s now an 18 minute gap between the next couplet between 96th St and Chambers, vs one every 9 minutes.

Its still a gap, but trains and staff blowing through regularly like that could mean the difference if some person gets “ideas” following someone - because there’s a smaller window.

Guess my question is whether that timed platform transfer at Nevins is more important and beneficial than evenly spaced headways in the entertainment cores in Manhattan.

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2 hours ago, Jsunflyguy said:

Assumed transfers most likely, if you had to get from 215th St to Nevins, would you rather take the (1) wait 3 minutes on the transfer or 8-10 minutes on the transfer.

If (1) ran in front of (2), sure. But unless it’s changed, it was typically (2) in front of (1).

Ideally, since you have three lines on the Westside 24/7, my concern (see above) could be solved with (1)(3) to South Ferry via Local and (2) via express overnight - (2) could keep the timed connect with (4) at Nevins, and (1) or (3) can time connect at Chambers or 72nd or 96th.

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5 minutes ago, Deucey said:

I guess my issue is “safety” - if (1) comes right after (2) overnight, there’s now an 18 minute gap between the next couplet between 96th St and Chambers, vs one every 9 minutes.

Its still a gap, but trains and staff blowing through regularly like that could mean the difference if some person gets “ideas” following someone - because there’s a smaller window.

Guess my question is whether that timed platform transfer at Nevins is more important and beneficial than evenly spaced headways in the entertainment cores in Manhattan.

Your last sentence sums up my feelings about the countdown clocks in the subway, especially when they were introduced. I have a few NYPD family members and when I brought them my concerns they said they were also conflicted by the safety vs convenience dilemma. We haven’t talked about it since then but if I have a chance I’ll bring it up. You’ve probably realized by now that some of these decisions are made by someone at a desk poring over “data” who has no clue what happens to the data when it comes to the real world. Stevie Wonder is probably more aware of the consequences then some of these cubicle dwellers. Just my opinion. Carry on.

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1 minute ago, Trainmaster5 said:

Your last sentence sums up my feelings about the countdown clocks in the subway, especially when they were introduced. I have a few NYPD family members and when I brought them my concerns they said they were also conflicted by the safety vs convenience dilemma. We haven’t talked about it since then but if I have a chance I’ll bring it up. You’ve probably realized by now that some of these decisions are made by someone at a desk poring over “data” who has no clue what happens to the data when it comes to the real world. Stevie Wonder is probably more aware of the consequences then some of these cubicle dwellers. Just my opinion. Carry on.

There was a time when I would be out in the city waiting on (N) or (1) to South Ferry with the other drunk folks and would be in 8th St/NYU or any of the 7th Av stations seeing drunks fight or eyeballing women standing alone.

I’m a big enough and intimidating looking brotha that if I looked in their direction these wolfpacks would rethink the ideas they had, but with NYPD not being in every platform, that 9 minutes could make the difference between something not happening to unies getting the perp and making “Benson & Stabler’s“ jobs’ much easier.

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5 hours ago, Deucey said:

I guess my issue is “safety” - if (1) comes right after (2) overnight, there’s now an 18 minute gap between the next couplet between 96th St and Chambers, vs one every 9 minutes.

Its still a gap, but trains and staff blowing through regularly like that could mean the difference if some person gets “ideas” following someone - because there’s a smaller window.

Guess my question is whether that timed platform transfer at Nevins is more important and beneficial than evenly spaced headways in the entertainment cores in Manhattan.

Well sure, but again in the base schedule it's written to work as you suggest -- the (1) and (6) can 'float' and end up perfectly in between the (2) and (4) service created by the Nevins transfer as they don't interact with lines aside from the (2) and (4). In fact, excluding the (3), the only part of the A division that doesn't get even headways overnight is the Eastern Parkway corridor, where they've decided an easy (2)(4) transfer at Nevins > evenly spaced service. It's when running supplemented service, especially when running schedules that rewrite service on one of the two lines but not the other, that this all gets messed up.

4 hours ago, Trainmaster5 said:

Your last sentence sums up my feelings about the countdown clocks in the subway, especially when they were introduced. I have a few NYPD family members and when I brought them my concerns they said they were also conflicted by the safety vs convenience dilemma. We haven’t talked about it since then but if I have a chance I’ll bring it up. You’ve probably realized by now that some of these decisions are made by someone at a desk poring over “data” who has no clue what happens to the data when it comes to the real world. Stevie Wonder is probably more aware of the consequences then some of these cubicle dwellers. Just my opinion. Carry on.

I don't see how countdown clocks prevent the scheduling of even headways? Or is your point that they may inform people as to how long they have before the train arrives if they're considering some untoward action? 

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1 hour ago, RR503 said:

Well sure, but again in the base schedule it's written to work as you suggest -- the (1) and (6) can 'float' and end up perfectly in between the (2) and (4) service created by the Nevins transfer as they don't interact with lines aside from the (2) and (4). In fact, excluding the (3), the only part of the A division that doesn't get even headways overnight is the Eastern Parkway corridor, where they've decided an easy (2)(4) transfer at Nevins > evenly spaced service. It's when running supplemented service, especially when running schedules that rewrite service on one of the two lines but not the other, that this all gets messed up.

I don't see how countdown clocks prevent the scheduling of even headways? Or is your point that they may inform people as to how long they have before the train arrives if they're considering some untoward action? 

Your last sentence. Bet Deucey gets it.

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17 hours ago, Trainmaster5 said:

Your last sentence sums up my feelings about the countdown clocks in the subway, especially when they were introduced. I have a few NYPD family members and when I brought them my concerns they said they were also conflicted by the safety vs convenience dilemma. We haven’t talked about it since then but if I have a chance I’ll bring it up. You’ve probably realized by now that some of these decisions are made by someone at a desk poring over “data” who has no clue what happens to the data when it comes to the real world. Stevie Wonder is probably more aware of the consequences then some of these cubicle dwellers. Just my opinion. Carry on.

So, we've had countdown clocks for several years now. Is there any evidence of crime going up in the intervals between train arrivals?

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44 minutes ago, Italianstallion said:

So, we've had countdown clocks for several years now. Is there any evidence of crime going up in the intervals between train arrivals?

I haven't had that discussion with people in the know. I know for a fact the situation Deucey has discussed that even before the countdown clocks there were certain people who took advantage of the overnight headways.  I've been on work trains that were not running  where the perps didn't even realize that they were being observed and watched people being robbed,  women being harassed, and gay and lesbian couples being physically assaulted. Between intervals.  My partners and  i intervened in some of those altercations and, as noted , the presence of 4 or more burly men usually changed the perpetrators minds.  There were times when the Transit Police showed up and advised us avoid the potential altercations. We've observed consensual sex acts ,  straight and gay,  in the rear of a (1) train in the South Ferry loop because everyone was in the first five cars of the train and no one realized that we were on the inactive diesel in the inner loop. This  was happening every weekend while we and the track guys were assigned to the tamper at Bowling Green. Has crime increased since the introduction of the clocks  ? I don't know but from my perspective it's certainly been made easier for some people.  I'm going back 30 years with my observations but even with the preponderance of cameras these days it hasn't really stopped the determined idiots. Unless you're a regular overnight commuter or a worker down there you would be surprised what goes on after midnight. Just my opinion.  Carry on. 

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27 minutes ago, Italianstallion said:

So, we've had countdown clocks for several years now. Is there any evidence of crime going up in the intervals between train arrivals?

Depends on which crimes you're interested in. I'd venture to say that given most sexual assaults aren't reported, that waiting 16 minutes for a train may give someone time to commit one and get away (even if it's just accosting or sexual battery), whereas 8 minute waits may be more likely to - if not deter it, make it more likely to have it reported.

Keep in mind we're getting $250 million to cover 500 (MTA) police without proof of an upswing in crime - so since "perceived deterrence" is the thing today, even headways should be considered since it doesn't cost anything more.

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