Most Numberous Box & Auto Cars

Michael Aufderheide

I’ve been working over the last few months going through Larry Ostrech’s 1950 excel ORER with the goal of finding out which individual box and auto car types are the most numerous.  For ease of discussion I’m calling these cars the “base fleet”.  The base fleet are cars in the national pool that show up at a given location simply because they are the most numerous.  The size of each modeler’s base fleet will be different, for me it is 200 boxcars.  These 200 cars won’t be the only boxcars on my layout.  Other cars of specific types and roads will run because of interchanges, industries, the season modeled, etc.  This specific group of cars I can account for through prototype paperwork. It's the anonymous cars that I want to determine. 
My 200 car base fleet means that any car in the national pool of 714,902 cars more numerous than 3,575 cars or ½% of the national fleet is automatically included.  It became apparent that too few cars made up this number in themselves to be counted. Tony Thompson had suggested using the percentage owned by individual railroad instead;  starting from a percentage of the national fleet that each railroad owned, and then taking that proportion as broken down in that road’s most numerous types.  His suggestion has worked well and it seems to be representative.  (Looking down the ORER there are few, if any smaller roads that would have car types making up the necessary 1/2%.)
Of course the base fleet number will vary with each modeler’s needs.  As a modeler’s base fleet expands so does the number of cars, but also the variety of cars and the number of railroads represented.  Other base fleet sizes require the following minimum number of prototype cars (714,902 cars/desired base fleet):
100 car base fleet needs 7,149 prototype cars for each model
200 cars base fleet needs 3,575 prototype cars for each model
300 cars base fleet needs 2,385 prototype cars for each model
400 cars base fleet needs 1,787 prototype cars for each model
500 cars base fleet needs 1,430 prototype cars for each model
etc. etc. etc…..
I’m happy to share my annotated excel file with anyone who wants to expand the search past what I’ve done.  I'll post it to the group once I have corrections/input from everyone.
In order to make this exercise useful, I have needed to generalize the characteristics of these cars.  For instance, I have not been concerned with the type of trucks, doors, running boards, or ends, but only a general, simplified description.  Generalization is not encouraged on this list, so I ask your forbearance.
In the 1950 ORER I found cars with similar:
Key dimensions (I.H., I.L., door size, door number)
Type of construction(if listed): steel, ss, ds
Type of car: box, auto, or vented
Variations of a few inches are allowed in this, but this might be too much as I’ve discovered in some cases.  For example knowing what is and is not a rebuild is difficult from the ORER.
There are other variables like SS, DS, Steel and length.  We know what these percentages are of the national fleet, so some corrective measures will be needed to represent the true percentages of these cars.  This will be added to the base fleet number and will take a bit of doing...something for the future.
I’ll post the results of this by letter of the alphabet with the hope that those of you more in-the-know can help correct my mistakes.  I will list available models if I can.
Mike Aufderheide

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