The DS/SS split - By Inside Height


laramielarry <ostresh@...>
 

Hi Folks

One of the great charms of the steam era boxcar fleet is the ragged
nature of rooflines on a long string of cars. Getting a quantitative
answer to the proportion of cars of various heights, so as to better
capture the feel of the era on my layout, was a major motivation for me
to digitize the mid-Twentieth Century ORER in the first place.

This is a summary of the distribution of inside height, IH, for box,
auto, and ventilator cars in the July 1950 ORER, further divided into
double sheathed, single sheathed and steel. IH varies from a low of 4'
11" (MILW series 8000-8474) to a high of 12' 4" (UP, 4 consecutive
series 562000-564199), but such extremes are rare. In fact, over half
the fleet has an IH of one or another of the following exact dimensions:
8' 7", 10' 0", 10' 6". Here are the DS/SS/Steel splits for these car
heights (I apologize for the ragged look of the tables - I've tried
several ways to get them to line up, but nothing seems to work):

8' 7" ______%____Number
DS_______3.1%____2,917
SS______22.3%___20,716
Steel____74.4%___69,006
Other____0.0%________0
Known___99.8%___92,639
Unknown__0.2%_____166
Total___100.0%___92,805
Percentage of fleet = 13%. Most are from just three railroads: PRR
(25,360; X29 = 23,635); NYC (17,394; including subsidiaries this rises
to 19,200); B&O (13,720).

(The "fleet" here referred to is box, auto, and ventilator cars owned by
U.S. railroads and in interchange service; as of the July 1950 ORER,
this was 715,073 cars.)

10' 0"_______%__Number
DS_______5.4%____9,226
SS______20.5%___35,154
Steel____72.1%__123,369
Other____1.5%_____2,482
Known___99.5%__170,231
Unknown__0.5%_____867
Total___100.0%__171,098
Percentage of fleet = 24%. Many of the steel cars are 1937 AAR
(53,844). Another 17,082 are 10 foot postwar; but a whopping 37,978 are
simply "steel" and of no particular (named) design. (Data for the 1937
AAR cars comes from a file created by Ed Hawkins and Ted Culotta,
available for download on the Steam Era Freight Cars (SEFC) web site.
Data for 10' postwar cars comes from a file created by Earl Tuson and
available for download here on STMFC. Both files were collated into the
digital ORER.)

10' 6"______%___Number
DS______0.0%________0
SS_______5.8%____8,201
Steel____93.9%__132,645
Other____0.0%______20
Known__99.7%__140,866
Unknown_0.3%______361
Total___100.0%__141,227
Percentage of fleet = 20%. Of the steel cars: 28,604 are 1944 AAR;
17,459 are modified 1937 AAR; 15,866 are 40' PS1; and 54,462 are
un-named "Steel". (Data for the 1944 AAR, modified 1937 AAR, and 40'
PS1 rosters come from files created by Ed Hawkins and available for
download from SEFC; I collated them into the digital ORER.)

Boxcars with an interior height of 9' 4" are sometimes cited as
an intermediate "standard" between 8' 7" and 10'
0"; in the 1950 ORER there were 17,571 such cars, 90% of them steel,
nearly all the rest SS.

The ORER lists over 80 individual car heights, some with a precision to
the nearest one-sixteenth of an inch; it is neither practical nor
desirable to list each IH with the detail given above. Rather, I
classified the heights into 3 inch bands, centered on (for example)
9' 9", 10' 0", 10' 3", 10' 6" . . . ,
and counted the cars in each band. This gave 15 classes, each of 3"
except for the first and last, which were open-ended (i.e., they
extended to the extrema of the data). Each band extends 1.5" above
and below the band centers – e.g., the 10' 0" band ranges
from 9' 10.5" to 10' 1.5"; cars were assigned to each
band if they were equal to or above its minimum and below its maximum.
I numbered the bands from 1 (highest IH) to 15 (lowest IH). Here are
the counts for each band:

Band; Center IH: Number

1; 11' 3": 949

2; 11' 0": 1,584

3; 10' 9": 22,256

4; 10' 6": 156,268

5; 10' 3": 60,083

6; 10' 0": 180,093

7; 9' 9": 4,841

8; 9' 6": 6,785

9; 9' 3": 49,797

10; 9' 0": 49,898

11; 8' 9": 14,337

12; 8' 6": 12,3438

13; 8' 3": 7,567

14; 8' 0": 2,9137

15; 7' 9": 8,040

Band 1 extends from 11' 1.5" to 12' 4"; band 15 extends
from 4' 11" to 7' 10.5". All the rest extend +-
1.5" from Center IH.



Here is an attempt to visualize the above table:



01

02

03 ***

04 **********************

05 ********

06 *************************

07 *

08 *

09 *******

10 *******

11 **

12 *****************

13 *

14 ****

15 *

My intention in this "graph" was to distribute 100 stars in
proportion to the numbers in the preceding table, but because of
rounding only 99 appear. The meaning is this: If you have a fleet of 99
box/auto cars and want the heights to reflect the U.S. fleet in 1950,
you would want 7 cars from band 10 (IH from 8' 10.5" to 9'
1.5") and 2 from band 11 (IH from 8' 7.5" to 8'
10.5"). On the assumption that the "graph" will be
unreadable when I post this, here are the numbers of stars in each band:



01, 0

02, 0

03, 3

04, 22

05, 8

06, 25

07, 1

08, 1

09, 7

10, 7

11, 2

12, 17

13, 1

14, 4

15, 1



Here is the DS/SS/Steel split, categorized by IH band. Each row
contains the band ID, center IH, and (successively) the number of DS,
SS, and steel cars; the number of "Unknowns" is not shown; the
number of "Other" types is appended only if it exceeds 200
(usually it is zero).



Band; Center IH = Number DS; SS; Steel

1, 11' 3"= 0; 374; 387

2, 11' 0"= 0; 0; 1,584

3, 10' 9"= 20; 2,384; 19,752

4, 10' 6"= 196; 10,003; 145,333

5, 10' 3"= 2,167; 8,078; 49,208

6, 10' 0"= 9,254; 35,234; 132,144 (+ 609 ATSF "Panel" and 1,863
GN "Plywood" cars)

7, 9' 9"= 95; 178; 4,460

8, 9' 6"= 0; 4,249; 2,532

9, 9' 3"= 6,248; 11,643; 31,828

10, 9' 0"= 7,232; 26,014; 16,564

11, 8' 9"= 8,565; 1,861; 3,732

12, 8' 6"= 5,028; 45,020; 70,961 (+ 1,993 ATSF "Panel" cars)

13, 8' 3"= 7,085; 260; 0

14, 8' 0"= 12,936; 15,498; 529

15, 7' 9"= 6,865; 688; 378

Totals = 65,691; 161,484; 479,392



Next is an attempt to graph the above table: d = double sheathed, s =
single sheathed, t = steel. There are 100 letters; to mimic the
mid-Twentieth Century fleet in terms of IH and construction type with
100 cars, you would have, for example, 8 cars in IH band 9 (9'
3" +- 1.5"): 1 DD, 2 SS, and 5 steel.

01 -

02 -

03 ttt

04 sttttttttttttttttttttt

05 sttttttt

06 dsssssttttttttttttttttttt

07 t

08 s

09 dssttttt

10 dsssstt

11 dt

12 dsssssstttttttttt

13 d

14 ddss

15 d

There are 9,504 ventilator cars, primarily in size classes 13 (2,088);
14 (3,614); and 15 (3,228).



I hope no one infers from my above tables that I am suggesting that
one's fleet SHOULD mimic the IH or construction type of 1950 or any
other era – my intent is merely to provide some data for those who
may wish to consider that option.



As a reminder: All of you have free access to the Excel file version of
the July 1950 ORER. It contains the car heights from which you can
construct many of the tables above. It also has a rudimentary division
into DS/SS/Steel (collations of USRA DS, USRA SS files, and several
files that divide "steel" into 1923 ARA, 1932 ARA, etc., up to
50' PS1 – all posted at various times by members of this
group.). This file can be downloaded from Mike Brock's Steam Era
Freight Car Analysis (STEFA) site. To access the file, you will first
need to become a member of the group:

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Best wishes,

Larry Ostresh

Laramie, Wyoming













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