Author Topic: Sometimes a compound ladder doesn't win  (Read 1500 times)

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Ed Kapuscinski

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Sometimes a compound ladder doesn't win
« on: July 09, 2018, 10:48:21 AM »
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I've been playing with some TTRAK yard designs lately and discovered something interesting.

Usually, compound yard ladders result in more car capacity at the expense of prototype fidelity.

However, in playing with a design using Kato #4s, I've found a scenario where it's not quite true.

Take a look.

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C855B

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Re: Sometimes a compound ladder doesn't win
« Reply #1 on: July 09, 2018, 10:55:16 AM »
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Plus a fairly ugly reverse curve, too.

Odd. Maybe something to do with the Kato geometry? Or possibly there is less to be gained with shorter switches.
...mike

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We don't make mistakes, we have happy accidents. We just don't tell anybody. -Bob Ross

wcfn100

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Re: Sometimes a compound ladder doesn't win
« Reply #2 on: July 09, 2018, 10:59:38 AM »
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I'm not sure I'd even call that a compound ladder.  The key to a compound ladder is the second right hand turnout and the tracks that come off of it.  You only have one track and you mucked it up with another turnout.

Jason
« Last Edit: July 10, 2018, 12:48:07 PM by wcfn100 »

Ed Kapuscinski

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Re: Sometimes a compound ladder doesn't win
« Reply #3 on: July 09, 2018, 11:00:59 AM »
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Plus a fairly ugly reverse curve, too.

Odd. Maybe something to do with the Kato geometry? Or possibly there is less to be gained with shorter switches.

Yep, I think the short switch lengths might be exactly the reason here.

Ed Kapuscinski

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Re: Sometimes a compound ladder doesn't win
« Reply #4 on: July 09, 2018, 11:01:46 AM »
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I'm not sure I'd even call that a compound ladder.  The key to a compound ladder is the second right hand turnout and the tracks that come off of it.  You only have one track and you much it up with another turnout.

Jason

Yep, I think that's another good point too. The top yard track COULD be a lot longer, but it's not because of the switch.

up1950s

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Re: Sometimes a compound ladder doesn't win
« Reply #5 on: July 09, 2018, 11:27:55 AM »
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Some do and some don't but over all it don't . More even length tracks with a compound . On a long ladder that may be desired .

Paradise275

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Re: Sometimes a compound ladder doesn't win
« Reply #6 on: July 09, 2018, 11:47:54 AM »
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If you put an extra RH switch before the first switch shown off the main to bring it up to the track shown that joins nothing, then use LH switches from that lead to join into the top tracks you would get longer yards there.

Rick

jdcolombo

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Re: Sometimes a compound ladder doesn't win
« Reply #7 on: July 09, 2018, 03:56:21 PM »
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If you use a compound design with the main yard lead at the top or bottom, the yard tracks will be more uniform in length, but shorter than the first and second tracks of a simple ladder.  E.g.:

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The simple ladder in the above example has shorter tracks the farther you go up the ladder.  You may or may not get more overall car capacity with a compound - it depends on the length of the turnouts and how many yard tracks there are.  But you DO get tracks that are of more uniform length.

Compound ladders are also useful when the yard lead needs to come into the yard from closer to the center track, instead of the upper or lower track:

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My staging yards are of this design, and again you will get more uniform track length, which is particularly useful for staging.

John C.

« Last Edit: July 09, 2018, 04:02:08 PM by jdcolombo »

OldEastRR

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Re: Sometimes a compound ladder doesn't win
« Reply #8 on: July 10, 2018, 01:41:11 AM »
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The "bible" says the compound ladder "makes a considerably more compact yard with more uniform track lengths."  So the main advantage for a compound is this, not more storage.
You have been lead astray, my son.  :trollface:

GaryHinshaw

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Re: Sometimes a compound ladder doesn't win
« Reply #9 on: July 10, 2018, 11:51:55 AM »
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John's diagram shows pretty clearly that a compound ladder has to win by simple geometry: the tracks fill more of the yard area than the simple ladder does, at the expense of more curvature.  Ed's example is not a simple compound ladder due to the trailing point turnout on the last track.  If you omit that, his compound ladder has more capacity too.  (I think this is the point Jason was making.)

Cajonpassfan

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Re: Sometimes a compound ladder doesn't win
« Reply #10 on: July 10, 2018, 12:20:32 PM »
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In a given (rectangular) space, compound ladders do win and do provide more total track capacity then simple ladders. And yes, as Gary says, at times at the cost of more s-curves...which may or may not be a problem depending on track components and geometry. This becomes more apparent the more tracks are added.

I gained quite a bit of capacity (and made the tracks less inconsistent in length) by using compound ladders in my hidden "Barstow" staging yard, see below. There are 14 tracks, the turnouts are the old, bullet-proof #6 Shinohara Code 70, and the s-curves have not been an issue. Of course, the compound ladder advantage diminishes with fewer tracks involved.
Otto K.
« Last Edit: July 10, 2018, 12:25:03 PM by Cajonpassfan »

babbo_enzo

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Re: Sometimes a compound ladder doesn't win
« Reply #11 on: July 10, 2018, 12:27:24 PM »
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"Usually, compound yard ladders result in more car capacity at the expense of prototype fidelity."
Sorry Ed, but a compound have a High degree of fidelity and is very popular on our prototype. And.. as said by others, not because get more car capacity.
And.. if you start the compound "before" the curve... see here how many space can gain:
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C855B

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Re: Sometimes a compound ladder doesn't win
« Reply #12 on: July 10, 2018, 12:53:27 PM »
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...very popular on our prototype. ...

Well, then, not in the U.S. Somewhat rare here, compounds are mainly used in circumstances where space is at a premium or it is desirable to have even distribution of capacities on each yard track, such as hump yards. Therein lies one key component that makes compound ladders "reasonable" - remote- or other automatically-controlled switches. The other benefit of compound ladders off the hump is shorter roll-out distance for the outer tracks; there's heck to pay when a balky car stops in the middle of the ladder, so short ladders are good.

Compound ladders are typically avoided in flat yards because of the safety issues of personnel crossing active tracks to throw switches. With conventional ladders, all the throws can be accessed to the outside of the ladder. Suggest you might take a look at one of the many satellite-view websites to overview pretty much any modern hump yard, and you will find compound ladders descending from the hump, and conventional straight ladders at the trim (output) end of the yard, where the operation is predominately manual.
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Ed Kapuscinski

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Re: Sometimes a compound ladder doesn't win
« Reply #13 on: July 10, 2018, 01:39:26 PM »
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Well, then, not in the U.S. Somewhat rare here, compounds are mainly used in circumstances where space is at a premium or it is desirable to have even distribution of capacities on each yard track, such as hump yards. Therein lies one key component that makes compound ladders "reasonable" - remote- or other automatically-controlled switches. The other benefit of compound ladders off the hump is shorter roll-out distance for the outer tracks; there's heck to pay when a balky car stops in the middle of the ladder, so short ladders are good.

Compound ladders are typically avoided in flat yards because of the safety issues of personnel crossing active tracks to throw switches. With conventional ladders, all the throws can be accessed to the outside of the ladder. Suggest you might take a look at one of the many satellite-view websites to overview pretty much any modern hump yard, and you will find compound ladders descending from the hump, and conventional straight ladders at the trim (output) end of the yard, where the operation is predominately manual.

Exactly. It doesn't matter in hump yards because the switches are all thrown remotely by a computer. In flat yards, you don't want to make your brakeman do all that walking for safety and efficiency reasons.

davefoxx

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Re: Sometimes a compound ladder doesn't win
« Reply #14 on: July 10, 2018, 03:01:21 PM »
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Compound ladders are typically avoided in flat yards because of the safety issues of personnel crossing active tracks to throw switches. With conventional ladders, all the throws can be accessed to the outside of the ladder.

^This.

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