Re: New member checking in
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Bruce is correct. If you dig into the archives you will find plenty of discussion on this topic. I don’t recall now when I first posted about it; Tim Gilbert joined in shortly afterwards and wrote far more extensively that I did.
The “rule” we advocated was an even distribution of box and flat cars on mainline routes from around the start of WWII to sometime in the 50’s. By even distribution I mean numbers proportionate with the ownership numbers from each road.
For my part I tallied over 1000 foreign road boxcars on a mainline in North Carolina from wheel reports. The sum of each foreign road was sorted highest to lowest and then compared to an ordered list of road names showing their total numbers of boxcars. The two ordered lists matched up well down the list, finally pulling away from each other (IIRC) down in the 1% and less totals. I then compared the percentages and with one or two very minor exceptions they too matched.
There was no data available to me from before WWII or after the mid 50’s, nort was there any data for way out in the boonies branch lines so the rule is qualified accordingly. Additionally, I have examined urban traffic and was surprised that the number of house cars were much less than I expected. I do not know if that was a unique case but it does occur to me that with a large flow of inbound boxcars there might be very little need for roads to hang on to home road cars for protective service. The opposite may well be true for very far out in the boonies, low traffic locations – few inbounds might mean more home road cars are needed for protection. Both of those opinions could be useful to hobbyists.
Tim Gilbert’s research showed the same was true for flat cars.
Looking at the data there I could find no such relationship for any other type of cars and that sounds right because many of those cars either did not leave home rails or if they did the numbers were quite small. Consider stock cars: Texas was the state that provided California more cattle than any other state – and it’s a decently long run. The problem is both SP and ATSF do all the way between those two points so those cars never had to leave home rails.
Another example: There is photo evidence of NW hoppers in Indiana and MP hoppers in Utah. Turns out this was low volume shipments of coking coal headed to steel mills. They were on a regular circuit and so unlike box and flat cars they did not wander about to be spotted off that circuit… they were simply out and back loads. Almost all tank cars were on a steady circuit between two locations… no wandering. Reefers did wander… but the available data is not large enough to draw a good conclusion.
From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Bruce Smith
Sent: Saturday, June 25, 2022 12:12 PM
Subject: Re: [RealSTMFC] New member checking in
The bottom line is that several extensive analyses, across much of the country, show that non-home road boxcars appear, over time, and many trains, in approximately their proportion of the national fleet. Yes, there are lots of exceptions, for example trains specifically designed to interchange with another road will be biased to that road (but other trains will have proportionally fewer of the same road), and branches with focused traffic, especially when those cars are in pools will be biased to the pool members, but for a general pool of cars, the best data to date says that the national poll percentage will produce the best results. There are and should be more PRR boxcars than SP boxcars on the Northern Pacific.