#### Re: Freight car distribution

Malcolm Laughlin <mlaughlinnyc@...>

"Ah ha! I think I can agree with that. My point all along has been that certain RRs probably have more of their box cars...and perhaps other cars...on the tracks of a RR with a closely integrated operation... UP/SP. Perhaps UP/C&NW. The cars of other RRs...with some exceptions.. .might well follow the national %."

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You would normally see a higher than the average number of home road cars of any general service car type for a few simple reason. When cars were not needed they were sent home. Most railroads did try to observe the Car Service Rules, with varying degrees of compliance. Many cars went thoruogh shop programs or were stored, usually on the owning road.

Personal recollections, on the NYC I did see many more box NYC cars and gons than I would have seen on the PRR. Opposite was true on PRR.

It is true that on most of the large class 1's you were going to see marks of all other class 1's. But the proportions would differ subtley as you moved away from the home road. You would see a lot of NYC cars on the SP, but not nearly the same proportion as on the Wabash. You'd see a few WP cars on the NYC, but a much higher proportion on the Rio Grande.

I would be very wary of any interptretation of statistics that varies far from common sense. The problem is that the samples that we see as model railroaders are rarely large enough to draw firm conclusions. Ther fallacy in designing an arithmetic algorithm to estmate distribution of cars from available data because you want a set of numbers is that the result doesn't have to be meaningful in any specific context. None of us can model the average railroad.

I'll offer as a suggestion to model railroaders a simple algorithm for calculating fleet proportions. Weight the percentage of ownership of each other railroad by its distance from you road. Give direct connections a weight of 1.0. Give the most distant other railroad a weight of 2 or 3 (this is arbitrary, play with it until you get a result you like). Then interpolate for other railroads based on distance.

Don't use the distance for the nearest junction, use the middle of the railroad - to avoid bias from extensions like SP to New Orleans or NYC to Cairo. Use a ruler on a mpa of the US and use distances in inches.

Precision doesn't matter. It's a waste of time to try for too much accuracy. The objective shouldn't so much as to have an average of the prototype as to have a flow of cars that gives a feeling of realism as the trains go by.

Malcolm Laughlin, Editor 617-489-4383
New England Rail Shipper Directories
19 Holden Road, Belmont, MA 02478

Malcolm Laughlin, Editor 617-489-4383
New England Rail Shipper Directories
19 Holden Road, Belmont, MA 02478

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