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Siding and Interchange Track Lenght

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Siding and Interchange Track Lenght
Posted by Teamanglerx on Sunday, June 21, 2009 1:44 PM

I am designing a shelf layout and have run into a small problem.  On the layout I would like to have a interchange track that holds 6 cars plus a loco (inbound cars would be moved to industries and outbound cars would be placed on this track to be moved "out").  If I have a interchange this long (I am in N scale and figured 35"-40") would I also need a siding this lenght to switch or could I get away with a smaller siding (say 20"-25")?

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Posted by cowman on Sunday, June 21, 2009 4:18 PM

If your interchange track is not part of a working line and the cars are "in order" when put there, a shorter siding should work.  Two shorter sidings might give you a better option.  Do you have room for a runaround track?  If so, one  track could be inbound, the other outbound, yet still with a way around the parked cars after the exchange was completed.

Just a couple of thoughts.

Have fun,

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Posted by tomikawaTT on Sunday, June 21, 2009 4:46 PM

It all depends on how you operate the interchange.  Assuming that the interchange will be switched trailing-point (aka, 'The easy way') and that the siding is behind the interchange frog:

If you have the interchange full, pull the entire cut as a unit and replace it with a cut of similar length, you need a siding as long as the interchange track.

If you have the interchange track full but only pull half of it to redistribute, leaving a similar-length cut, your siding needs to be long enough to clear the cut being worked and the caboose, if used.  However, your loco must be able to pull the entire content of the interchange without fouling the next town.

If you have the length of line before the next town, you can cut the cars to be spotted, pull the entire content of the interchange track, back down and pick up the cut to be left, switch that cut into the interchange and then reassemble the train.  Your locomotive will need enough power to move a cut twice the length of the interchange.

If things are really cramped, you might have the local pull some or all of the cars on the interchange track without leaving any replacements.  Another local will then drop cars without pulling any.  No siding required.

In my case, the interchange track is switched from the yard lead, and the switcher can double a long interchange cut into two yard tracks if it doesn't simply classify it.  OTOH, the four staging tracks adjacent to my cassette dock are all longer than the cassettes, so swapping out full-length trains is no problem.

Chuck (Modeling Central Japan in September, 1964)

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Posted by nucat78 on Monday, June 22, 2009 10:31 AM

tomikawaTT

It all depends on how you operate the interchange. 

True.  "Most" prototypes would pull the whole string down and then switch / sort them.  But you can always pull a couple, switch 'em, pull a couple more, switch 'em , and so on if you don't mind a lot of seesawing back and forth.  Considering this is a switching layout, that might be exactly what you want.

As a general rule, I try to make my IXC tracks, passing sidings, and yard tracks equal to the length of the longest train I would run, but each to his own...

 

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Posted by R. T. POTEET on Monday, June 22, 2009 11:53 AM

Usually sidings are longer than interchange tracks but there is nothing written in blood that requires that. In fact interchange tracks can be miles long. Railroad A pushes its interchange cut to the far end of the interchange track where it is left for railroad B to pick up. Railroad B does the same thing with its interchange cut for Railroad A.

Technically you can move a locomotive from one end of a train to the other with only a one car siding . . . . . . . . . . although it can take one heckuva lot of moves to do it. You drop the first car of a train in the siding, back out onto the main and pull forward to pick up the second car. You back it into the siding, drop it there, and push the first car onto the main where it is dropped. You now do the same thing with the third and second car. Sooner or later you will get to the last car and your locomotive will now be at the opposite end of the train from where it was located when you first arrived.

With a very long train this can take all day and the accounting department is not likely to be appreciative of all the red ink it puts in the ledger book.

From the far, far reaches of the wild, wild west I am: rtpoteet

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Posted by Mill Bay on Friday, August 21, 2009 7:29 PM

Does anyone have any suggestions for how to lay out a siding in N scale to achieve the greatest length on the siding track itself without having a really long transition curve off the turnout points in order to get the correct spacing between the siding and parallel main track? When using sectional track, the turnouts usually come with a transition curve section, but it is usually such a broad radius, it takes up a fair amount of potential siding length.

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Posted by nucat78 on Saturday, August 22, 2009 10:29 AM

Mill Bay

Does anyone have any suggestions for how to lay out a siding in N scale to achieve the greatest length on the siding track itself without having a really long transition curve off the turnout points in order to get the correct spacing between the siding and parallel main track? When using sectional track, the turnouts usually come with a transition curve section, but it is usually such a broad radius, it takes up a fair amount of potential siding length.

I think the obvious answer is to use flex track.  You want to be careful that your curve is not so tight that your locos and rolling stock have trouble negotiating it though.

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Posted by johncolley on Saturday, August 22, 2009 10:30 AM

Just for the info, here is my philosophy: Your longest train can be any length as it can use the main to run by, but your second longest train (including power and caboose if used) must fit completely inside the siding clearance points to permit any other train to pass. Keep this in mind if you are pulling additional cars from interchange. example: if you are going to pull 6 cars off intchg, then your pickup train must be at least 6 cars shorter than the siding. Rule no.1- Don't foul the main if you don't have "track and time" allowed between passing trains! John

jc5729
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Posted by Paulus Jas on Saturday, August 22, 2009 1:31 PM

hi tea

to be blunt, give more information!!  Draw a trackplan and the room your pike has to fit in and post it on the forum.

You have an awkward situation; same as with switchbacks. Operating should remain fun, but you have to find the balance suited to you. You can try it out, or change the plan: the other RR delivers not 6 cars at the same time, but the eastbound three and a couple of hours later a westbound another three. Or change the trackplan, that is why would to like to see the whole plan.

!!!Mill Bay, get off this thread; use your own!!! 

Tea, if you need help, just ask. We all learned by asking, you'll always find people to help you. 

Paul

 

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Posted by Texas Zepher on Saturday, August 22, 2009 3:12 PM

nucat78
tomikawaTT
It all depends on how you operate the interchange. 
True.  "Most" prototypes would pull the whole string down and then switch / sort them.

It depends on the era, but in general I disagree.  I say prototypes would treat the interchange like any other siding.  Drop outgoing cars off and pick up incoming.   Incoming cars would be taken to a classification yard somewhere to be sorted for their destinations.   Interchange to classification yard then back to the industries.  Oh the other hand, really busy exchanges are most often associated with a classification yard rather than industrial trackwork.

In Denver, the track coming in at the very top of the photo on the right is the interchange to the UP.  Note how it comes across the whole picture and curves back up on the left going straight into the 23rd street yard.


Here is the other end of that track. Coming in on the left above the MOW equipment. Notice that it curves and goes straight into the west end of the UP yard (where the locos are sitting).   Side note,  Notice all the parking lots to the right.  At one time that was all rail yard.  Now it is Coor's field parking lot.

On the other end of the loco shops is the interchange from the former D&RGW North Yard.  As that track curves off to the right it goes straight into the yard lead of the 23rd street yards.

I've got many more examples of this but don't have pictures of them.  Interchange tracks aren't really photogenic most of the time.
 

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Posted by 4merroad4man on Saturday, August 22, 2009 5:50 PM

Teamanglerx

I am designing a shelf layout and have run into a small problem.  On the layout I would like to have a interchange track that holds 6 cars plus a loco (inbound cars would be moved to industries and outbound cars would be placed on this track to be moved "out").  If I have a interchange this long (I am in N scale and figured 35"-40") would I also need a siding this lenght to switch or could I get away with a smaller siding (say 20"-25")?

I have to agree with another poster....we need more info.

If the siding will be used to "bang em out" and switch the inbound cars to place them in order for local industries, then a short siding would be fine given a few parameters:

1.  You could only switch a few cars into the siding at a time, since it would be shorter than the interchange.

2.  Since outbounds would be in a "who cares" order, the siding would be useless, except to hold excess or overflow outbounds, or to hold outbounds when the interchange is full of inbounds.  Outbounds that are in excess of the two tracks' capacity could be held in a nearby yard.

In any event, switching would not be by taking the entire track and working it, rather you would need to shuffle cars in a manner similar to the little five cent game us oldsters remember, that had the numbeed tiles with one vacant slot.

Provide a drawing of the situation if you can, and that will make the situation a little clearer.

Serving Los Gatos and The Santa Cruz Mountains with the Legendary Colors of the Espee. "Your train, your train....It's MY train!" Papa Boule to Labische in "The Train"
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Posted by Teamanglerx on Sunday, August 23, 2009 5:25 PM

I started this thread way back when and it was a dead thread until someone recently added to it.  I used the advice from when I first posted but I appreciate the other hints and help you have all provided.

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Posted by Blazzin on Sunday, November 22, 2009 1:31 PM

  Teamang, I found this to be of use and I must admit I have never seen / read it before.  I plan on adding this particular thread link as useful reading for others.  I also thank you all for the advice and found it quite interesting ..and cause me to stop and think.

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Posted by Doc in CT on Sunday, November 22, 2009 2:24 PM

There is a nice discussion of this topic (along with diagrams) in John Armstrong's Track Planning for Realistic Operation.

Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/

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