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Jemorie

Williamsburg Bridge Capacity

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15 hours ago, m2fwannabe said:

3230-33 are here (!!) as of Wed Mar 27 2019.  That should close out deliveries for March.

3010-19 reportedly have had issues addressed with the Automated Announcement System.  A Road Test is slated for this week, then (Maybe?) it goes back in service.

3218-21 have undisclosed (correctable) minor defects.  Testing with 3214-17 continues.

If things go well, 3222-29 should be wandering around on the system next week.

There is now only one more sequential 4-car delivery, presumably 3234-3237 by April 5, then (again presumably and finally) 3070-3073 by April 12 to complete that portion of the contract.

From there we will all hopefully learn more about the remaining 5-car sets for the (A).

 

One more four-car set on the run? Sweet. Hopefully by the end of April, the (M) will run much more frequently as officially planned. There are more than enough four-car R179s to make it work. The Middle Village to Manhattan direction during the AM Rush (and reverse in the PM Rush) needs the extra service as the current 10 minute headways aren't cutting it. It should match the current combined (J) / (Z) skip-stop headways (5 minutes) to make the Williamsburg Bridge 24 tph in the 8:00 a.m. hour instead of the current 18 tph (6 (J) 's, 6 (Z) 's and 6 (M) 's it has now).

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3 hours ago, Jemorie said:

One more four-car set on the run? Sweet. Hopefully by the end of April, the (M) will run much more frequently as officially planned. There are more than enough four-car R179s to make it work. The Middle Village to Manhattan direction during the AM Rush (and reverse in the PM Rush) needs the extra service as the current 10 minute headways aren't cutting it. It should match the current combined (J) / (Z) skip-stop headways (5 minutes) to make the Williamsburg Bridge 24 tph in the 8:00 a.m. hour instead of the current 18 tph (6 (J) 's, 6 (Z) 's and 6 (M) 's it has now).

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

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42 minutes ago, whz1995 said:

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

Unless you send the (J) and (Z) express.

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5 hours ago, Lawrence St said:

Unless you send the (J) and (Z) express.

The middle village bound (M) still blocks everything 

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6 hours ago, whz1995 said:

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

I believe the Willamsburg Bridge approaches at Marcy and Essex are the main capacity limitation... @RR503 care to chime in on this?

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42 minutes ago, Around the Horn said:

I believe the Willamsburg Bridge approaches at Marcy and Essex are the main capacity limitation... @RR503 care to chime in on this?

Yeah, Ikr. The curves and the complex switches are the problems. I also don’t believe Williamsburg bridge could handle 24tph because the trains run very very slow on the bridge. 

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Posted (edited)
9 hours ago, whz1995 said:

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

 

3 hours ago, Maxwell179 said:

The middle village bound (M) still blocks everything 

 

2 hours ago, Around the Horn said:

I believe the Willamsburg Bridge approaches at Marcy and Essex are the main capacity limitation... @RR503 care to chime in on this?

 

1 hour ago, whz1995 said:

Yeah, Ikr. The curves and the complex switches are the problems. I also don’t believe Williamsburg bridge could handle 24tph because the trains run very very slow on the bridge. 

You guys should see how packed Manhattan-bound (M) trains in Brooklyn are in the morning rush hour though. They're packed before they even reach Myrtle-Broadway and have been so for years. Yet trains on the line in that particular direction are every 10 minutes. Matching the headways with the current 5-minute headway on the combined (J)(Z) will work. And some downtown-bound (M) trains can terminate at 2nd Avenue and head back up to Queens like they did before. Trains run very slow throughout the WillyB because of the many timers throughout the bridge. I think I remember one time the (MTA) even stating that the (M) is above guideline at rush hour too. With the four-car R179 order almost finished, it will help. Anyway, I'll save this for another discussion for some other time.

Edited by Jemorie

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12 hours ago, Jemorie said:

One more four-car set on the run? Sweet. Hopefully by the end of April, the (M) will run much more frequently as officially planned. There are more than enough four-car R179s to make it work. The Middle Village to Manhattan direction during the AM Rush (and reverse in the PM Rush) needs the extra service as the current 10 minute headways aren't cutting it. It should match the current combined (J) / (Z) skip-stop headways (5 minutes) to make the Williamsburg Bridge 24 tph in the 8:00 a.m. hour instead of the current 18 tph (6 (J) 's, 6 (Z) 's and 6 (M) 's it has now).

 

9 hours ago, whz1995 said:

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

 

8 hours ago, Lawrence St said:

Unless you send the (J) and (Z) express.

 

3 hours ago, Maxwell179 said:

The middle village bound (M) still blocks everything 

 

2 hours ago, Around the Horn said:

I believe the Willamsburg Bridge approaches at Marcy and Essex are the main capacity limitation... @RR503 care to chime in on this?

 

1 hour ago, whz1995 said:

Yeah, Ikr. The curves and the complex switches are the problems. I also don’t believe Williamsburg bridge could handle 24tph because the trains run very very slow on the bridge. 

 

13 minutes ago, Jemorie said:

 

 

 

You guys should see how packed Manhattan-bound (M) trains in Brooklyn are in the morning rush hour though. They're packed before they even reach Myrtle-Broadway and have been so for years. Yet trains on the line in that particular direction are every 10 minutes. Matching the headways with the current 5-minute headway on the combined (J)(Z) will work. And some downtown-bound (M) trains can terminate at 2nd Avenue and head back up to Queens like they did before. Trains run very slow throughout the WillyB because of the many timers throughout the bridge. I think I remember one time the (MTA) even stating that the (M) is above guideline at rush hour too. With the four-car R179 order almost finished, it will help. Anyway, I'll save this for another discussion for some other time.

You also have to factor in terminal capacities, and interlining with other routes.  

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3 minutes ago, Jemorie said:

 

 

 

You guys should see how packed Manhattan-bound (M) trains in Brooklyn are in the morning rush hour though. They're packed before they even reach Myrtle-Broadway and have been so for years. Yet trains on the line in that particular direction are every 10 minutes. Matching the headways with the current 5-minute headway on the combined (J)(Z) will work. And some downtown-bound (M) trains can terminate at 2nd Avenue and head back up to Queens like they did before. I think I remember one time the (MTA) even stating that the (M) is above guideline at rush hour too. With the four-car R179 order almost finished, it will help. Anyway, I'll save this for another discussion for some other time.

I know M is extremely crowded during rush hour because I used to take it everyday. But the fact is the tracks and switches can't handle more train, and you need to consider the capacity of the 53rd tunnel and the forest hill terminus which are both running about the limit. Just as I said, increasing M service must affect other services as in the original L shutdown plan, MTA was planned to cut the Z service and make J fully local to have more M train.

But I think MTA could try to make some Manhattan bd J/Z terminate at Broadway junction since most of people transfer there.

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21 minutes ago, whz1995 said:

I know M is extremely crowded during rush hour because I used to take it everyday. But the fact is the tracks and switches can't handle more train, and you need to consider the capacity of the 53rd tunnel and the forest hill terminus which are both running about the limit. Just as I said, increasing M service must affect other services as in the original L shutdown plan, MTA was planned to cut the Z service and make J fully local to have more M train.

But I think MTA could try to make some Manhattan bd J/Z terminate at Broadway junction since most of people transfer there.

That  wouldn't work.  For as many on the Manhattan bound j/z get off at Junction to transfer,  just as many transfer TO the Manhattan bound J/Z from the A, C, and L trains.  In would know.  I'm one of them. 

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14 minutes ago, Far Rock Depot said:

That  wouldn't work.  For as many on the Manhattan bound j/z get off at Junction to transfer,  just as many transfer TO the Manhattan bound J/Z from the A, C, and L trains.  In would know.  I'm one of them. 

I think anyone who's on the (A) or (C) (manhattan bound) is NOT going to get off and take the (J) thats a suicide of time. From the (L) I can see somewhat feasible. 

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Posted (edited)
10 minutes ago, VIP said:

I think anyone who's on the (A) or (C) (manhattan bound) is NOT going to get off and take the (J) thats a suicide of time.

There's a good number of people who want that connection actually, certainly not worthy of straight up slashing IMO (even with reduced service). I know the (M) is crowded to the brim, but lets not handle this by cutting travel options for others while ignoring the consequential issues associated with such.

Edited by NoHacksJustKhaks
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12 hours ago, whz1995 said:

I think the switch at myrtle's ave is the limitation. You cannot have more M train without affecting JZ service.

Also, QBL. I may be exaggerating a little, but almost everyday, there are issues that causes delays along QBL during rush hour and the M is impacted by the delays.

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The biggest limits are on the Myrtle junction (easy fix with upper level reactivation and Lewis Av el/curve) and Willy B (hard fix). In the long-term I would prefer to have a 3 or four track tunnel to replace the Willy B given the lack of space and curves needed to cross it.

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2 hours ago, whz1995 said:

I know M is extremely crowded during rush hour because I used to take it everyday. But the fact is the tracks and switches can't handle more train, and you need to consider the capacity of the 53rd tunnel and the forest hill terminus which are both running about the limit.

That's just plain not true. In 1954 the Williamsburg Bridge handled 26 tph in peak. We currently run 18 tph.

Also note that it says the upper limit for the bridge is 32 tph. Better operating practices can support that level of service.

1954.gif

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2 hours ago, whz1995 said:

I know M is extremely crowded during rush hour because I used to take it everyday. But the fact is the tracks and switches can't handle more train, and you need to consider the capacity of the 53rd tunnel and the forest hill terminus which are both running about the limit. Just as I said, increasing M service must affect other services as in the original L shutdown plan, MTA was planned to cut the Z service and make J fully local to have more M train.

But I think MTA could try to make some Manhattan bd J/Z terminate at Broadway junction since most of people transfer there.

Gentrification!! I know that I'm talking politics, but the L and M run on neighborhoods that have been invaded by hipsters resulting in ridiculous high rents and displacement of low income people in those areas These hipsters go to the universities near 14th street, so they jam pack the L and M.

In fact, I used to ride the L and M trains 12 to 15 years when there were no hipsters and the L and M trains didn't get crowded not even during rush hour.

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2 hours ago, VIP said:

I think anyone who's on the (A) or (C) (manhattan bound) is NOT going to get off and take the (J) thats a suicide of time. From the (L) I can see somewhat feasible. 

You obviously don't frequent like I do.   Trust me.  All three lines there sees riders changing between the two.  Yes,  even from the A to the J Manhattan bound. 

I make that same trip every-day and yes,  there are many who come off the A,  trek up that long escalator and get on the J Manhattan bound 

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8 minutes ago, R68OnBroadway said:

The biggest limits are on the Myrtle junction (easy fix with upper level reactivation and Lewis Av el/curve) and Willy B (hard fix). In the long-term I would prefer to have a 3 or four track tunnel to replace the Willy B given the lack of space and curves needed to cross it.

That was planned by the TA during the 80's, but it was scrapped and the Willy B was renovated instead.

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Posted (edited)
24 minutes ago, Around the Horn said:

That's just plain not true. In 1954 the Williamsburg Bridge handled 26 tph in peak. We currently run 18 tph.

Also note that it says the upper limit for the bridge is 32 tph. Better operating practices can support that level of service.

1954.gif

True but the speed limit was lowered as a result of the deadly train crash that happened on the Willy B in 1995.

https://www.nydailynews.com/new-york/subway-crash-kills-driver-injures-54-1995-article-1.690727

 

Edited by subwaycommuter1983
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14 minutes ago, Around the Horn said:

That's just plain not true. In 1954 the Williamsburg Bridge handled 26 tph in peak. We currently run 18 tph.

Also note that it says the upper limit for the bridge is 32 tph. Better operating practices can support that level of service.

That's a phenomenal map. Never seen that before -- great find and post.

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37 minutes ago, MHV9218 said:

That's a phenomenal map. Never seen that before -- great find and post.

Thanks! I remember seeing it somewhere so I did some digging and found it on the Joe Korner.

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6 hours ago, Around the Horn said:

I believe the Willamsburg Bridge approaches at Marcy and Essex are the main capacity limitation... @RR503 care to chime in on this?

Yes. The exits kill capacity. The 10mph curves at both end basically mean you’d have to have a following train enter the station before the leader leaves, which is, to say the least, not what happens today. I don’t think you’d be able to get to 30 without making Myrtle sticky, but you could certainly do more (the mix between (J) and (M) of course matters here). 

4 hours ago, Jemorie said:

 

 

 

You guys should see how packed Manhattan-bound (M) trains in Brooklyn are in the morning rush hour though. They're packed before they even reach Myrtle-Broadway and have been so for years. Yet trains on the line in that particular direction are every 10 minutes. Matching the headways with the current 5-minute headway on the combined (J)(Z) will work. And some downtown-bound (M) trains can terminate at 2nd Avenue and head back up to Queens like they did before. Trains run very slow throughout the WillyB because of the many timers throughout the bridge. I think I remember one time the (MTA) even stating that the (M) is above guideline at rush hour too. With the four-car R179 order almost finished, it will help. Anyway, I'll save this for another discussion for some other time.

(M) runs nine trains per hour AM rush, but is at something like 90% guideline cap. Increase is necessary, but not slated. Keep in mind generally that the guidelines themselves are wonky — 3 square feet per person borders on inoperable crowding levels. So really, much over 80 needs to be looked at. 

To the general point though, the most restrictive limit on (M) service today is Forest Hills. Unless you cut (R) service (which is what was planned for (L) shutdown) there’s no way you can add more than 1tph to the line before you hit FH limits. FH is completely fixable, though — it’s a question of rigor more than anything else. Beyond FH, WillyB will limit you at 12 (assuming you don’t cut (J)(Z)), 6th Ave at 14, and 53 at 15. 

1 hour ago, Around the Horn said:

That's just plain not true. In 1954 the Williamsburg Bridge handled 26 tph in peak. We currently run 18 tph.

Also note that it says the upper limit for the bridge is 32 tph. Better operating practices can support that level of service.

1954.gif

Thank you for inserting this map into the conversation. Understanding historical capacity is essential to understanding current problems. I’m working up a sheet that has historical maximum throughputs on track segments and plan to post when finished. For now, another similar map can be found at the end of this doc. 

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2 hours ago, Around the Horn said:

That's just plain not true. In 1954 the Williamsburg Bridge handled 26 tph in peak. We currently run 18 tph.

Also note that it says the upper limit for the bridge is 32 tph. Better operating practices can support that level of service.

1954.gif

I mean all the tracks that are used by M train. Ironically, I took the J trains across willy b twice yesterday and both J trains lost their races with bikers. 

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Posted (edited)

There are some misconceptions about the relationship between speed and capacity that I’d like to clear up. 

First of all, what happens between stations isn’t nearly as important as what happens immediately around stations. Think about it like this: you have 2 trains running 2 minutes apart on some track. Train one stops at a station and dwells for 45 seconds — now trains 1 and 2 are at most 1:15 apart. What determines how long it will be until train 2 gets in the station (and thus your headway) is how fast train 1 can exit the station, how fast train 2 can enter the station, and how long the signal system’s enforced separation between them is. In essence, the signal system around stations generally has the most impact on operational performance. (Of course, merge/terminal capacity play a big role too, but station limits are most relevant to this conversation)

This isn’t of course to say that interstations are unimportant. When you’re dealing with a conga line or some other irregular operational situation, you want a signal system capable of moving things along well. But for normal operations, unless your interstation signals are incapable of handling 2 min train separations (which is extremely rare) you’re fine. 

This brings me to my next point: slow speeds don’t *necessarily* mean less capacity. Signal systems are designed to simply enforce adequate train separation so that a train traveling at maximum area speed can stop. Thus if a signal system is designed around some enforced slow speed, train separation in the area will be less, which basically preserves your capacity. Where speed issues arise is if enforced slow speeds are retrofitted onto signal systems that were designed for higher speeds. Then you lose capacity.

Bringing this back to the Williamsburg Bridge, the capacity issue isn’t so much the timers on the bridge — the signals are spaced per the timer limits — it’s the signal design at the ends of it. Trains are held too far back from the stations given the ridiculously slow speeds entering Marcy and Essex (10mph to both). Fixing that probably means resignalling or changing those stations’ configurations, but it’d definitely be worth it. 

Edited by RR503
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