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Union Tpke

Why Your Subway Train Might Start Moving Faster

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I'm listening to the video and "Safety" is such a buzz word. It's like they have to reiterate "safety" and "safely" a million times because of all the propaganda which gives a negative connotation to the word "speed".  🙄

Speed does not automatically cause accidents. You should see some comments on highway stories. People think that going the (artificially low) speed limit magically prevents accidents from happening, it's amazing.  We need Germany to be in charge of our highways.

 

 

 

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3 hours ago, 7-express said:

I thought it was to control for noise through the curve and to help prevent excessive rail wear.

Skeptical of that. We have no issue flinging trains around curves elsewhere. If I had to make a totally unsubstantiated guess, it's something to do with CBTC's interaction with the terminal area. 

2 hours ago, RestrictOnTheHanger said:

Any such installations in place right now?

And what happened with the 4th ave express track GTs? I dont get into Brooklyn at all

Yes. Pretty much anywhere you have a long downhill is an example of this, as are long express segments that got GTs during resignallings (rather than during mods), like A4 on CPW. An article detailing why this is true, if you're interested (read from "Time Control Scheme").

The northbound 4th Avenue express used to be a track with capacity-positive GTs -- I believe they were GT40s. Anyway, for whatever reason, RTO got them removed, which required signal control lines to be lengthened. For cost's sake, they just chose to extend them to the next signal, creating massive train separation distances. Not so much of an issue in regular ops, but it's one of the things that wrecks work train interactions. 

Edited by RR503
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21 hours ago, RestrictOnTheHanger said:

There was an AMNY article saying that Lex and the (M) just got some speed upgrades. Any places besides Union Sq, Canal St, and Fresh Pond Rd?

49003424737_0397af0b83_c.jpgScreen Shot 2019-10-31 at 6.57.56 PM by Union Turnpike, on Flickr

49002680628_9b1b335e2b_c.jpgScreen Shot 2019-10-31 at 6.58.49 PM by Union Turnpike, on Flickr

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@RR503 Yesterday, as the T/O of my (F) was waiting for the lineup at 75th, he was doing pushups in the cab against his seat. That was a first. Once we got yellow over yellow we were in the station for a minute or so because 71st Master put the holding lights on for some reason.

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13 hours ago, Union Tpke said:

@RR503 Yesterday, as the T/O of my (F) was waiting for the lineup at 75th, he was doing pushups in the cab against his seat. That was a first. Once we got yellow over yellow we were in the station for a minute or so because 71st Master put the holding lights on for some reason.

 

As I have said before, faster speeds are meaning less when trains have to hold in every station to make up the time they saved.

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13 hours ago, Union Tpke said:

@RR503 Yesterday, as the T/O of my (F) was waiting for the lineup at 75th, he was doing pushups in the cab against his seat. That was a first. Once we got yellow over yellow we were in the station for a minute or so because 71st Master put the holding lights on for some reason.

Ugh. 

7 minutes ago, Gotham Bus Co. said:

As I have said before, faster speeds are meaning less when trains have to hold in every station to make up the time they saved.

Yeah but...this isn't true. Most of the time, a hold will be for some connection or for a gap rather than to hold to time. And at any rate, holds to time affect only those trips which pass through the hold point. 

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This report, which came out yesterday, has some really interesting discussion of a lot of the issues we've discussed here previously. Highly recommend giving it a read. 

https://new.mta.info/sites/default/files/2019-12/MTA NYCT Subway Speed and Capacity Review_Final Report.pdf

Some key takeaways in my eyes:

- NYCT acknowledges the operational issues at Nostrand/142/149, and acknowledges the need to make investments/routing changes

- NYCT acknowledges R68 propulsion issues (and also gives a bunch of really interesting data on pre- and post-field shunting elimination acceleration profiles for various car classes)

- Lots of good stuff on timer/speed sign visibility

- Disappointing lack of analysis of dwell time issues and off peak service problems

- Super interesting applications of axle counters to shorten fixed dwells at force and lock controlled interlockings

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13 minutes ago, RR503 said:

This report, which came out yesterday, has some really interesting discussion of a lot of the issues we've discussed here previously. Highly recommend giving it a read. 

https://new.mta.info/sites/default/files/2019-12/MTA NYCT Subway Speed and Capacity Review_Final Report.pdf

Some key takeaways in my eyes:

- NYCT acknowledges the operational issues at Nostrand/142/149, and acknowledges the need to make investments/routing changes

- NYCT acknowledges R68 propulsion issues (and also gives a bunch of really interesting data on pre- and post-field shunting elimination acceleration profiles for various car classes)

- Lots of good stuff on timer/speed sign visibility

- Disappointing lack of analysis of dwell time issues and off peak service problems

- Super interesting applications of axle counters to shorten fixed dwells at force and lock controlled interlockings

Did they ever do a similar report on say, 34th or 11th St?

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9 minutes ago, R68OnBroadway said:

Did they ever do a similar report on say, 34th or 11th St?

There’s one in the pipeline, IINM. Unsure whether it’ll be made public. 

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5 hours ago, RR503 said:

There’s one in the pipeline, IINM. Unsure whether it’ll be made public. 

Even if it isn't from the outset, you could always submit a FOIL request. I've had pretty good luck with those (I have an old Tappan Zee rail study sitting around somewhere), even if they're not responded to in the most timely of manners.

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8 minutes ago, bobtehpanda said:

Even if it isn't from the outset, you could always submit a FOIL request. I've had pretty good luck with those (I have an old Tappan Zee rail study sitting around somewhere), even if they're not responded to in the most timely of manners.

You are an outlier then.

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20 hours ago, Union Tpke said:

You are an outlier then.

Waiting for the day I can find out why they chose 125th and Lex over 3rd and 149th for SAS.

Especially now that we know the price tag.

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1 minute ago, LTA1992 said:

Waiting for the day I can find out why they chose 125th and Lex over 3rd and 149th for SAS.

Especially now that we know the price tag.

You will see in Phillip Plotch's book which will come out later this year.

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The R68 propulsion discussion is fantastic to see happening. However, ideally I would like to see an analysis of the signal control lines and spacing from before trains’ brakes were modified in the early 90s, which is what eventually led to the Williamsburg crash. If it’s not considered “safe” to revert the trains’ performance to 1940s-90s design levels, maybe the brakes need to be reverted back to design specs as well (inshot valves, etc). The system ran fine that way for 50 years...

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1 hour ago, Union Tpke said:

You will see in Phillip Plotch's book which will come out later this year.

Thank you.

This will make a perfect compliment to 722 Miles and The Routes Not Taken.

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Posted (edited)
On 1/2/2020 at 2:59 PM, LTA1992 said:

Waiting for the day I can find out why they chose 125th and Lex over 3rd and 149th for SAS.

Especially now that we know the price tag.

Realistically, to get backing from suburban politicians with the connection to Metro-North, and to keep the project simpler by keeping it in Manhattan (as sending it to an outer borough opens up a new can of worms). Also I know "Phase 2 should have gone to 149 St" discussions come up every other month in the SAS thread, but the big price tag shouldn't really matter either way; it's not like going 149 St wouldn't have the same cost issues as any other Capital Construction megaproject, and presumably would have been even more expensive, what with one additional station (with the stations being the most expensive elements of Phase 1) and having to build transfers to the (6) and (2)(5), and an underwater crossing, albeit a short one. 

Edited by Mysterious2train

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3 hours ago, Mysterious2train said:

Realistically, to get backing from suburban politicians with the connection to Metro-North, and to keep the project simpler by keeping it in Manhattan (as sending it to an outer borough opens up a new can of worms). Also I know "Phase 2 should have gone to 149 St" discussions come up every other month in the SAS thread, but the big price tag shouldn't really matter either way; it's not like going 149 St wouldn't have the same cost issues as any other Capital Construction megaproject, and presumably would have been even more expensive, what with one additional station (with the stations being the most expensive elements of Phase 1) and having to build transfers to the (6) and (2)(5), and an underwater crossing, albeit a short one. 

Uh, when Lex and 125th alone is expected to cost half the proposed budget, yeah, we have a problem.

With the amount they want to spend on that section, you may as well build an immersed tunnel under the (very short) Harlem River and take it to The Hub. And yes, it might be somewhat more expensive, but the overall gains are worth it. Because it guarantees The Bronx two new lines.

Lastly, The Bronx should be world's cheaper to tunnel through. You won't have to do it anywhere near as deep compared to Manhattan. Property values are nothing compared to Manhattan. For all we know, it might cost the same.

But until I see the two options quantified into numbers, the "capitulating to the suburbs" response isn't good enough.

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On 1/2/2020 at 1:40 PM, Amtrak706 said:

The R68 propulsion discussion is fantastic to see happening. However, ideally I would like to see an analysis of the signal control lines and spacing from before trains’ brakes were modified in the early 90s, which is what eventually led to the Williamsburg crash. If it’s not considered “safe” to revert the trains’ performance to 1940s-90s design levels, maybe the brakes need to be reverted back to design specs as well (inshot valves, etc). The system ran fine that way for 50 years...

The issue isn’t that today’s brakes are worse than before — they’re about the same; one of the first efforts post-WillyB was upping brake cylinder pressures so that train stopping distances conformed with previous standards — it’s that the signal system/train relationship as it existed pre-1995 was unsafe in many areas even at undegraded brake performance. That was the realization forced by the accident. 

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8 hours ago, RR503 said:

The issue isn’t that today’s brakes are worse than before — they’re about the same; one of the first efforts post-WillyB was upping brake cylinder pressures so that train stopping distances conformed with previous standards — it’s that the signal system/train relationship as it existed pre-1995 was unsafe in many areas even at undegraded brake performance. That was the realization forced by the accident. 

That is what many people have been lead to believe, but it’s not the whole picture. Brake mods in the 80s and early 90s were the real issue, not signal control lines and spacing. Take a look at this, it’s a good read and explains a lot of what I am talking about.

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On 1/4/2020 at 10:40 PM, Amtrak706 said:

That is what many people have been lead to believe, but it’s not the whole picture. Brake mods in the 80s and early 90s were the real issue, not signal control lines and spacing. Take a look at this, it’s a good read and explains a lot of what I am talking about.

No, it’s the other way around. Setting aside  its inaccuracies and spurious details, that post tells about half of the true story — ie the mods that led to the brake degradation which in turn caused the collision. It does not cover, however, the actions taken by the authority after the crash to restore brake performance. For those, read the MTAIG report on the crash (h/t @Union Tpke)

https://drive.google.com/file/d/1ICyGZNzCg_JjWxQe_APl4Ua-eEXMFtfa/view?usp=drivesdk

And this (h/t @Stephen Bauman)

https://drive.google.com/file/d/1WwN5B2dl7zgouxaGPOjX1hi8uqFSowoQ/view?usp=drivesdk

Generally, the premise that GT/control lines mods are just a function of braking distances is itself flawed. Numerous other assumptions about train operator performance (ex: whether or not it was safe to allow sub-100% safety margins on signals which would only be last before a train ahead if a TO had proved their awareness by clearing a ST, whether trains actually slow to 15mph, whether they obey posted limits at switches, etc) and train performance (1.75mphps starting acceleration of an R1 vs 2.5 for R10 and onwards) changed over time, all of which required corrective action for signal systems designed by legacy standards. Those risks were unknown and then ignored until the Williamsburg Bridge crash finally prompted action. 

[Edit]: Another key point: there isn't a 1:1 relationship between brake rates observed in stopping distance tests and those used in signal design. Today, we assume trains brake at 1.4 mphps for the purpose of signal design as that was the value arrived at in a 1999 test of absolute worst case braking conditions. Not all signal designs assume worst case braking, however, which in turn causes even more design variance.

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Posted (edited)
1 hour ago, RR503 said:

No, it’s the other way around. Setting aside  its inaccuracies and spurious details, that post tells about half of the true story — ie the mods that led to the brake degradation which in turn caused the collision. It does not cover, however, the actions taken by the authority after the crash to restore brake performance.

Can you elaborate on these inaccuracies and spurious details? And how would a lack of coverage of the TA’s post-crash decisions somehow invalidate a write-up of the pre-crash events?

1 hour ago, RR503 said:

Generally, the premise that GT/control lines mods are just a function of braking distances is itself flawed. Numerous other assumptions about train operator performance (ex: whether or not it was safe to allow sub-100% safety margins on signals which would only be last before a train ahead if a TO had proved their awareness by clearing a ST, whether trains actually slow to 15mph, whether they obey posted limits at switches, etc) and train performance (1.75mphps starting acceleration of an R1 vs 2.5 for R10 and onwards) changed over time, all of which required corrective action for signal systems designed by legacy standards. Those risks were unknown and then ignored until the Williamsburg Bridge crash finally prompted action. 

Is there any evidence the IND (then BOT or TA) did not take this into account when designing the R10 and up and their compatibility with the existing system? How come this type of crash hadn’t happened prior to the brake mods? There were plenty of crashes, but as far as I know, none were due to insufficient emergency braking performance after hitting a tripper.

1 hour ago, RR503 said:

[Edit]: Another key point: there isn't a 1:1 relationship between brake rates observed in stopping distance tests and those used in signal design. Today, we assume trains brake at 1.4 mphps for the purpose of signal design as that was the value arrived at in a 1999 test of absolute worst case braking conditions. Not all signal designs assume worst case braking, however, which in turn causes even more design variance.

That sounds reasonable, but at some point there are so many different safety margins and allowances designed into various parts of the system that they begin to have a serious impact on everything else. Didn’t the IND engineers allow for a 35% safety margin on the control lines to mitigate this sort of thing?

Edited by Amtrak706
Clarity

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57 minutes ago, Amtrak706 said:

Can you elaborate on these inaccuracies and spurious details? And how would a lack of coverage of the TA’s post-crash decisions somehow invalidate a write-up of the pre-crash events?

IINM some of this is covered downthread of that post, but the focus on inshot is unjustified given its peripherality to emergency braking in general and the degradation in specific — it was brake cylinder pressure mismatches during the cast iron/composition changeover that killed things.

It invalidates it because the TA didn’t make mod decisions off of degraded brake performance. They made it after having restored brake function, a point at which (as you’ll see in the reports attached to my above post) there still existed significant numbers of safety deficiencies in the system.

1 hour ago, Amtrak706 said:

Is there any evidence the IND (then BOT or TA) did not take this into account when designing the R10 and up and their compatibility with the existing system? How come this type of crash hadn’t happened prior to the brake mods? There were plenty of crashes, but as far as I know, none were due to insufficient emergency braking performance after hitting a tripper.

As I understand it, the changeover was rationalized in two ways. 1) operators were expected to be competent and not dead/sleeping/suicidal, and 2) acceleration increases ate into but did not generally surpass the margin of safety provided by the signal system. Both assumptions held true, and were not generally put to test because a LOT has to go wrong for these deficiencies to get discovered heuristically (somebody operating a train in exactly the way that gets you to MAS, doing so facing a red signal with a train at a specific location ahead, etc). The brake mods just made it _that_ much easier for these things to be laid bare. Again, recommend you read the reports I linked because they a lot of these issues and lay out how safety issues went beyond just brake degradation.

1 hour ago, Amtrak706 said:

That sounds reasonable, but at some point there are so many different safety margins and allowances designed into various parts of the system that they begin to have a serious impact on everything else. Didn’t the IND engineers allow for a 35% safety margin on the control lines to mitigate this sort of thing?

For sure there are some redundancies (ex: assuming worst possible brake rate while also providing 35% safety margin), but there really isn’t much overlap between assumptions otherwise. Switch approaches, operator behavior and acceleration performance all determine interrelated but not overlapping bits of signal design.

IND engineers allowed 35% outside stations, 10% inside. This is basically what saved the system from the R10s, but again it was a design that relied on a lot of assumptions about operator performance that didn’t stand in reality.

When I’m back in NYC, I will do a more proper write up of the history here. It’s worth understanding fully. 

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16 hours ago, RR503 said:

It invalidates it because the TA didn’t make mod decisions off of degraded brake performance. They made it after having restored brake function, a point at which (as you’ll see in the reports attached to my above post) there still existed significant numbers of safety deficiencies in the system.

Oh ok, I see what you mean.

16 hours ago, RR503 said:

As I understand it, the changeover was rationalized in two ways. 1) operators were expected to be competent and not dead/sleeping/suicidal, and 2) acceleration increases ate into but did not generally surpass the margin of safety provided by the signal system. Both assumptions held true, and were not generally put to test because a LOT has to go wrong for these deficiencies to get discovered heuristically (somebody operating a train in exactly the way that gets you to MAS, doing so facing a red signal with a train at a specific location ahead, etc). The brake mods just made it _that_ much easier for these things to be laid bare. Again, recommend you read the reports I linked because they a lot of these issues and lay out how safety issues went beyond just brake degradation.

For sure there are some redundancies (ex: assuming worst possible brake rate while also providing 35% safety margin), but there really isn’t much overlap between assumptions otherwise. Switch approaches, operator behavior and acceleration performance all determine interrelated but not overlapping bits of signal design.

IND engineers allowed 35% outside stations, 10% inside. This is basically what saved the system from the R10s, but again it was a design that relied on a lot of assumptions about operator performance that didn’t stand in reality.

The fact remains, though, that this type of wreck did not occur prior to the 90s. If this was just due to a lower probability of it happening before the brake mods were added to the situation, then that probability was low enough to meaningfully change the risk/reward involved in running the system that way. I still think it's worth an analysis (which is not in the two sources you provided, although those were very interesting - thanks for the links).

16 hours ago, RR503 said:

When I’m back in NYC, I will do a more proper write up of the history here. It’s worth understanding fully.

I'll be interested to read that. I do appreciate your detailed and thoughtful responses.

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17 hours ago, RR503 said:

IINM some of this is covered downthread of that post, but the focus on inshot is unjustified given its peripherality to emergency braking in general and the degradation in specific — it was brake cylinder pressure mismatches during the cast iron/composition changeover that killed things.

It invalidates it because the TA didn’t make mod decisions off of degraded brake performance. They made it after having restored brake function, a point at which (as you’ll see in the reports attached to my above post) there still existed significant numbers of safety deficiencies in the system.

As I understand it, the changeover was rationalized in two ways. 1) operators were expected to be competent and not dead/sleeping/suicidal, and 2) acceleration increases ate into but did not generally surpass the margin of safety provided by the signal system. Both assumptions held true, and were not generally put to test because a LOT has to go wrong for these deficiencies to get discovered heuristically (somebody operating a train in exactly the way that gets you to MAS, doing so facing a red signal with a train at a specific location ahead, etc). The brake mods just made it _that_ much easier for these things to be laid bare. Again, recommend you read the reports I linked because they a lot of these issues and lay out how safety issues went beyond just brake degradation.

For sure there are some redundancies (ex: assuming worst possible brake rate while also providing 35% safety margin), but there really isn’t much overlap between assumptions otherwise. Switch approaches, operator behavior and acceleration performance all determine interrelated but not overlapping bits of signal design.

IND engineers allowed 35% outside stations, 10% inside. This is basically what saved the system from the R10s, but again it was a design that relied on a lot of assumptions about operator performance that didn’t stand in reality.

When I’m back in NYC, I will do a more proper write up of the history here. It’s worth understanding fully. 

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

  • Recommends increasing allowable speed in curves from V4 to V6, reviewing curves not yet studied (NYCT weary of doing this-passenger comfort)
    o    Along 7th Avenue and Flushing Lines, curve speeds could be increased 1 to 8 mph
    o    Curves with radii between 750 and 1,600 feet are candidates for speed increases based on V6 up to 50 MPH
    o    Curves with radii between 1,600 and 2,000 feet are candidates for speed increases based on V5 up to 50 MPH
  • Issues that @RR503 have been raising for some time
    •   Signage at some locations are difficult to read
    • East 180th Street — might well be a location where meaningful time savings and capacity improvements can be achieved
    • 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 
    • Suggest that this should be reevaluated for straight routes and standard moves for 2 and 5 trains
  • 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
    • ATS triggers not updated since end of ATS project in A-Division
    • Posted speeds via lunar lights often washed out and hard to read; small and posted right at signals-hard to read
    •   "Improvements being evaluated as part of Utica Avenue Line Study." The study lives on!
  • Provides great methodology of how Save Safe Seconds has been done
    •      Evaluation of all posted 30-mph signed areas at curves
      • 50 candidates identified for potential improvements
    • Review of curves posted at 30 to 35 mph
    •    25 quick-wins where speeds have been increased
    •  Identification by RTO of locations where posted speeds have room for improvement
    •  Increasing speed through switches-some allow up to 25 mph, signing them-all limiting speeds are lack of signs
  • Interesting recommendations
    • "“Another option could be to utilize the middle track at 135th Street as a pocket track for 3 Line trains (not serving that station) to hold and wait for their slot to open. Some new crossovers would be required.”
    • @RR503 It seems like you literally wrote the report. You talked about making use of the center track at 135th Street a week before this came out, and I have never seen anyone proposing that.
    • Determine, via cost-benefit analysis, viable fixed block system modifications to increase speeds, line-by-line basis, based on capacity needs, coordinated with signal capital projects
    • Begin replacing timer relays with 200 electronic relays on hand
    • 600 to 900 priority GT locations
    • More frequent verification of train speedometers
    • 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
    •  Perform analysis of ATS trigger points for automatic routing on 7th Avenue Line and provide recommendations for optimization based on current schedules
    • Determine, via cost-benefit analysis, viable fixed block system modifications to increase speeds, line-by-line basis, based on capacity needs, coordinated with signal capital projects, Only implement changes if line capacity is not reduced
    •  Replace signs with high reflectivity, or just cleaning existing signs more regularly, or adding illumination (small lunar LED)
    • Advance warning signs (25 MPH ahead)-areas visibility an issue or a major speed change is needed
    • 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
    • “Adding these indications would be of very significant benefit for the time and cost involved”
    • 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
    • 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
  • 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
  • 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.
    • Do not know ether average performance of vehicles has not further degraded due to wear since 1997
    • 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
    • An in-depth review of propulsion for each fleet time would be required and hardware changes may be required to achieve higher performance-DC propulsion
    • 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
    • Eliminate the need for trains to extend dwell times
    • 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
    • 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?

 

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