Thursday, 10 August 2017

X factor layout design theory


I have been asked “What is an ‘X’ Factor layout?”  Well, simply, it is a method of arranging a point to point layout in a way that allows easy remarshalling of trains in staging yards after an operating session.

But I am getting ahead of myself.  So let’s head down the rabbit hole and explore some theory on why a layout needs staging yards. 

Staging yards are a way of hiding a lot of trains away from the scenery portion of the layout.  Consider staging yards to be the rest of the world.  Trains can be held there awaiting their opportunity to enter the layout proper, do some shunting, or stop at the station, and then depart somewhere else.  Once they have left the scene, then, they are then not expected to return – at least not in that operating session. 

Without staging yards, it is operationally difficult to integrate your layout into a much larger railway system.

Let us take, for example, the common 2.4 x 1.2 metre layout in a spare room.  This size is commonly used, as it is a sheet of plywood.  Access is on 3 sides. 





               
This layout has 2 stations, one on each side of the plywood, separated with a backscene.  Trains circulate  from one station to the other, maybe doing some shunting.  A tunnel hides the “oval”.  A lot of people start with this concept.    Rather limiting is what you might be saying, although you have to start somewhere.

Consider the track diagram below

                            Simple linear layout,  with  staging at each end

With a simple change, we can transform the 2.4 x 1.2 metre layout into the above point to point layout, which has trains travelling from somewhere to somewhere else.  This is where the “X” factor comes in.    



Original layout, with staging tracks along the wall.

I have located the staging yards along the walls of our spare room, although they could be placed almost anywhere – even in an adjoining room.   You will note that the “mainline” oval is not broken, and could be used for multiple laps before the train reaches the other staging yard.    Repeat for all trains, until the operation session is completed.  The “X” factor is the shared trackage between the staging yards, and the mainline oval.  To reset for the next operating session,  simply reverse the trains from one staging yard to the other, utilising the shared tracks
My Wagga layout is planned to have two 9 track staging yards (Albury Staging, and Junee Staging) at either end of the main line.  These staging yards will be located UNDERNEATH the main line.  Trains will be marshalled with locomotives at the front of the train.  Once the train has finished its run, it will have the locomotive at the buffer stop end of the other staging yard.   
Of course, there is a problem – how do you stop trains leaving one staging yard  from crashing into trains arriving, or departing the other staging yard?  I posed this question to the presenters of a “X factor layout” clinic at the 2015 NMRA Portland USA convention   I did not receive a satisfactory answer.
But there is a simple solution.  Keep one of the staging yards “inside” the layout.  And only use the crossover trackage when remarshalling, OR if running trains in a continuous loop.  I plan to use a shinohara scissors crossover in the “X” position.

The Wagga layout design has  two 9 track staging yards (Albury Staging, and Junee Staging) at either end of the main line.  Trains will be marshalled with locomotives at the front of the train.  Once the train has finished its run, it will have the locomotive at the buffer stop end of the other staging yard. 



                Detail, not to scale, of the staging yard throat, and X factor crossovers on my layout

My benchwork  is hoped to  includes a “void” at the rear of the Murrumbidgee river bridge, beyond the backscene.  This void location will have access to the scissors crossover, and has access to the staging yard throats, and can directly observe any trains leaving, and entering the mainline.  An ideal dispatcher role.  Only the dispatcher can change the pointwork on the scissors crossover.  I am not sure if I will need to re-run a train during an operating session, (eg second division of the Intercapital Daylight), but there is that option with the dispatcher.


                                         concept model, showing the dispatcher void

And why have I chosen 9 tracks per staging yard?  Well, many of the electronic DCC route selection modules have provision to throw 8 point motors – which equates to 9 stub tracks. I had arranged the yard design to minimise the “shelf width”, although they end up being twice as long.  The longest train is around 3.3 metres (10 car Auscsion Southern Aurora), so I will need sidings of this length


 Will that be enough tracks for a full operating session?  8 or 9 mainline trains in each direction?  Probably NOT.   But I am not yet locked in to this number, and the planning and pondering continues.  

1 comment:

  1. Rob, you should keep in mind James' Law of Staging Yard Capacity... "Work out how many tracks you think you will need, then double it and add one... but you still won't have enough!"

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