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Thursday, November 30, 2023

Hopper Traffic Flow

Mine shift job HC-39 heads across the Gloucester Fork arch bound for the marshalling yard, 
where it will send its coal loads off to market and pick up empties for the next op session.

Since no one asked, I thought it might be interesting to start a discussion on the flow of hopper cars...  I'd love to hear your philosophy and opinions - how do you handle bulk loads?  What's most important to you?

Guys who are better modelers than me (this means you!) often prioritize the beauty of the load over the flow of the hoppers, preferring cars to be permanently loaded.  I totally understand this, and I'm blessed to get to run on some gorgeous layouts that handle coal this way.  

However within my head - scary as that may sound - it's more important that the railroad seem to be going about its business on its own.   Meaning, I want to be merely a spectator and a railfan, interfering as little as possible with its traffic.  The more I have to think through and manipulate things during re-staging, the more recognizable the trains are when they emerge during ops.  And on my own layout at least, that pierces the fourth wall, and takes away some of the fun.  

HC-39 arrives at East Segway after an ops session to deliver its loads.  
The former BE-46 waits on an adjacent track to supply it and other shifters with empties.

So if the goal of ops is to try to run a layout like a real transportation system, on the SNR at least I just can't re-stage loaded cars back to the mines.  And just I can't take the loads out of shifters and send them back out with the same cars they just picked up.  It chafes, man.  For the simulation to work, I want to know that a mine's coal is going to all the way to market, and in the very empties that were delivered to its tipple to fill.  As I said, it's a scary place in my head.

Anyway...  In the era before unit trains, this tenet yields two important corollaries:
  1. Empties must be loaded at the mines between sessions.
  2. Hoppers must circulate randomly, with little identifiable repetition or pattern.


At the Permian Fuels Corp.'s Claymoor Mine, empties set out by FS-41 during the last op session 
are filled as delivered.  They'll await the return of FS-41 in the next session to pick them up.  

In implementing these rules on the SNR, the mine shifters' loads are combined to form new road trains during re-staging - and at the same time, the empties trains are broken up to supply hoppers back to the shifters.  Basically this mimics the work of a marshalling yard on the prototype, not to mention mimicking the distant consumption of coal once it's brought up and sent away.  And not having room for an actual coal yard, I still get to operate through that part of the cycle out in the light, between sessions. 

At East Segway, F-M #164 breaks up an empties-east job from the previous session, to re-supply the visiting shifters.  He'll marshal their setouts into a new loads-west road train for the next ops.

Arguments can be made that this is overkill and that no one will notice.  That is probably true, but - I will.  Plus it lets me enjoy running my own railroad even while doing behind-the-scenes work.

The flow looks something like this:

The upshot of this flow is that each hopper makes a single, complete circuit of the coal production loop, every time.  Just like life.

Since every re-stage of the layout sets up two monthly-ish op sessions, the diagram suggests it could be almost a year before any given hopper gets back to where it started.  And when it does, it's going to be in a very different mix of cars than in the previous round.  Just like back in school - you went through 12 years with the same group of people, but every class in every year was a different subset. 

With its marshalling work complete and its symbol changed, new shift job HE-38 
threads through the interlocking at SE tower and gets out of town, bound for Gallipolis staging.

This all is what the world looked like to me as a kid when I first discovered coal trains, rolling up the B&O through Springdale.  There didn't seem to be any detailed mechanics or obvious repetition at work - just loads moving west and empties moving east, continuously.  So that's always been what I wanted to see happen in my own model world.  

How about you?  Love to hear what you guys think, and what matters on your layout.  Thanks for reading!


Kanawha #1812 departs Segway for Amherst staging, with the shifters' loads 
having constituted a new TC-17, ready for the next ops.  


My business partner once remarked to me, being the CPA, that "Even your checklists have checklists."  This is from the attorney who couldn't follow a recipe to save his @$$, but that's a story for over beers.  He's right, though, and just to prove it - at the risk of drowning you in minutiae (don't read it!) - here's a sample of the Coal re-staging checklist.  And yes, it itself is represented by a single line item on the Overall re-staging checklist.