Southern Pacific Lines Coast Line Division “The Route of the Octopus”

Southern Pacific Lines

Coast Line Division

“The Route of the Octopus”

General Information

The Southern Pacific Transportation Company employed an Association of American Railroads method of naming its freight cars. There are 11 basic classifications along with some sub-classifications. The system consisted of letters, The Official Railway Equipment Register lists "shorthand" designations and definitions for all types of freight cars. In the back of most issues of the Official Railway Equipment Register or ORER are the definitions of all classes, with sketches to clarify the more complicated ones, so you can always look there to get the idea or to check a code you don’t recognize. Here are some of the most common:

Descriptive Designations

Class Fflatcars
Class Ggondolas
Class Hhoppers
Class Lspecial cars
Class MTmaintenance-of-way cars
Class Ncabooses
Class Rrefrigerator cars
Class Sstock cars
Class Ttank cars
Class Vventilator cars
Class Xbox cars

Most cars in general service had a terminal letter “M” as in XM, TM, SM, FM, etc. (supposedly M = merchandise). So in the absence of other information, I would guess one of the “M” categories for a particular car. But there are exceptions.
Tony Thompson

Sub Classes

Class “F” – FLAT CAR TYPE

FA – Flat car specifically equipped with superstructure or containers for transporting set-up vehicles, not suitable for miscellaneous
commodities.
FB – Bulkhead flat cars. Equipped with fixed or permanently attached movable bulkheads or ends a minimum of three feet in
height and flat floor for general commodity loading.
FBC – Flat car constructed with a center beam above the car deck from bulkhead to bulkhead.
FC – Flat cars specifically equipped to carry trucks, trailers, containers, chassis, or removable trailer bodies for the transportation of
freight in
TOFC/COFC service.
FCA – Flat car, articulated multi-unit, specially equipped to carry trailers, containers, chassis, or removable trailer bodies for the
transportation of freight in TOFC/COFC service.
FD – Depressed-center flat car of special construction having the portion of the floor extending between trucks depressed to provide
necessary head room for certain commodities.
FL – Flat logging car or logging truck. This is either a straight-deck flat car, with or without bulkheads or load restraining devices,
or car consisting of two trucks fitted with cross supports over truck bolsters; the trucks connected by a skeleton or flexible frame
and logs loaded lengthwise on cross supports.
FM – Ordinary flat car for general service. This car has flooring laid over sills and without sides or ends.
FW – Flat car with hole to enable lading to be lowered due to clearance limits.

Class “G” – GONDOLA CAR TYPE

GA – Open top car having fixed sides and ends and drop bottom, consisting of doors hinged crosswise of car to dump between rails.
GB – Open top car having fixed sides, fixed or drop ends and solid bottom, suitable for mill trade.
GD – Open top car having fixed or drop ends, solid bottom and sides equipped with doors for dumping.
GH – Open top car having fixed sides, drop ends & drop bottom, consisting of doors hinged at center sills to dump outside of rails.
GS – Open top car having fixed sides and ends and drop bottom, consisting of doors hinged at center sills or side sills to dump
outside and/or inside of rails.
GT – Open top car, having high fixed sides and fixed or hinged ends and solid bottom, suitable for unloading on dumping
machines only.
GW – Open top well-hole car for transportation of special commodities. A solid bottom car with fixed sides and ends, having one
or more openings or depressions provided in floor, permitting the lading to be lowered in order to obtain overhead clearance.

Gondola classes had a bunch of complications but the most common classes are GS for drop-bottom cars and GB for tight-bottom mill gondolas. Here is an example of the ORER sketch definition for the GS cars (there are altogether 13 sketches of different gondola classes in my 1953 ORER copy, though many of them are fairly unusual cars.)
Tony Thompson

Class “H” – HOPPER CAR TYPE

HFA – Open top, self-clearing car having fixed sides and ends and bottom consisting of divided hoppers at center with doors hinged
lengthwise, dumping outside and/or inside of rail; also one divided hopper, each end, extending from end of car to bolster with
doors hinged lengthwise of car and dumping outside of rails.
HK – Open top self-clearing car having fixed sides and ends and bottom consisting of two or more divided hoppers dumping
outside and/or inside or rails (includes former HD).
HM – Open top, self-clearing car having fixed sides and ends, and bottom consisting of two divided hoppers with doors hinged
crosswise of car and dumping between rails.
HMA – Open top, self-clearing car having fixed sides and ends and bottom consisting of two divided hoppers with doors hinged
lengthwise of car and dumping between rails (includes former HMB).
HT – Open top, self-clearing car having fixed sides and ends and bottom consisting of three or more divided hoppers with doors
hinged crosswise of car and dumping between rails.
HTA – Open top self-clearing car having fixed sides and ends and bottom consisting of three or more divided hoppers with doors
hinged lengthwise of car and dumping between rails (includes former HTB).

Hopper cars had even more variations than gondolas (there are 15 sketches in the 1953 ORER), but for many purposes one can rely on the two most common categories: twin cross-hoppers are HM, triples are HT. “Special” cars have codes beginning with “L” and that includes covered hoppers as class LO. Depressed-center flat cars are FD and TOFC cars are FC, while most other cars are FM, including heavy-duty cars, as long as they have flat decks.
Tony Thompson

Class “L” – SPECIAL CAR TYPE

LC – A box car with side doors and roof hatches. May be equipped with end doors.
LF – A flat car equipped to handle one or more demountable containers for the transportation of commodities not under
refrigeration. Note: not applicable to flat cars designed to handle containers in TOFC/COFC service or containers handling
setup vehicles.
LG – Gondola car equipped to handle one or more demountable containers for the transportation of commodities not under
refrigeration.
LM – A car equipped with one or more permanently enclosed tanks or containers, provided with one or more openings for loading
and equipped for pneumatic or gravity unloading. Car is suitable for handling certain dry powdered or granular commodities and
also low viscosity, non-dangerous liquid commodities.
LO – A permanently enclosed car, other than a box car, regardless of exterior or interior shape, for handling bulk commodities, with
or without insulation and provided with openings for loading through top or sides with weather-tight covers or doors. Car may
be provided with one or more bottom openings for unloading, with tight fitting covers, doors, valves, or tight fitting slide or gate
to prevent leakage of lading. Car may be provided with facilities for discharge of lading through openings in top or sides and may
have one or more compartments. Mechanical or other means may be provided within car to expedite loading or unloading (a
covered hopper).
LP – An open-top car having solid bottom and fixed ends equipped with sloping floor or longitudinal floor risers or side stakes for
the handling of pulpwood and not suitable for general commodity loading.
LS – A car of special construction having two separate interlocking units which form a car body. Units may be separated and load
interposed between and locked in place to form a complete transportation unit.
LU – An enclosed car with roof, having a special metal beam of heavy design at top of each side to support a series of retractable
overhead side doors and the appurtenances, or other types of doors, running substantially the length of car, which beams also
support the roof details. Car may be equipped with special loading devices or racks for handling various commodities.

Class “M”

MT – Training Unit equipped with training aids or modified to demonstrate components of the unit.

Class “N”

NE – All cabooses.

Class “R” – REFRIGERATOR CAR TYPE

RB – Bunkerless refrigerator car similar in design to an RS car with or without ventilating devices and with or without devices for
attaching portable heaters. Constructed with insulation in side ends, floor and roof to meet maximum UA factor requirement of
250 BTU/F/Hour for 50-foot cars and 300 BTU/F/Hour for 60-foot cars. Effective for cars ordered new after March 1, 1984.
Cars built or rebuilt prior to March 1, 1984, must have been constructed with a minimum of 3 inches of insulation in the sides
and ends and 3-1/2 inches in floor and roof based on the insulation requirements given in AAR Standard S-2010 or a thickness
reduced in proportion to the thermal conductivity of the insulation.
RBL – Car similar in construction to an RB type car, but equipped in addition with adjustable loading or stowing devices.
(10/57-4/99). Note: Cars equipped with interior side rails only, built new, rebuilt or reclassified on and after January 1, 1966, in
order to qualify for the "RBL" designation, shall have a minimum of four (4) usable side rails on each wall of car, each extending
from doorway to approximately four (4) feet from end of car.
RC – Refrigerator Car similar to an RB car using a cryogen to produce temperatures to transport frozen commodities.
RP – Mechanical Refrigerator car equipped with or without means of ventilation and provided with apparatus or other device for
furnishing protection against heat and/or cold. Apparatus operated by power other than through the car axle.
RPB – Mechanical Refrigerator. Similar to RP type car but designed primarily for use in bulk potato or similar type loading as cars
are equipped with interior slope sheets and conveyors and/or equipment for mechanical loading and unloading.
RPC – Mechanical Refrigerator car similar in design to an RP but equipped with permanently affixed container(s).
RPL – Mechanical Refrigerator. Similar to RP but equipped in addition with adjustable loading or stowing device.
RS – Bunker Refrigerator car equipped with ice bunkers. Designed primarily for use of chunk ice and with or without means of
ventilation.

Ice bunker reefers were RS, and those were the most common refrigerator cars in the transition era. An RS car equipped with meat rails was Class RSM, and that would the classification of many though not all meat-packer cars. “Bunkerless” insulated cars were RB, which applies to some insulated box cars as well as to cars which carried beer or beverage cargoes. Mechanical refrigerator cars were class RP (apparently P = power generation on board).
Tony Thompson

Class “S” – STOCK CAR TYPE

S – Car for transportation of livestock.
SM single-deck stockcar
SP poultry car

Class “T” – TANK CAR TYPE

T – Tank car. Tank car means any car which is used only for the transportation of liquids, liquefied gases, compressed gases, or
solids that are liquified prior to unloading. Car may be without underframe if container serving as superstructure is designed to
serve as underframe. If car has underframe, it must be designed only for the carriage of one or more enclosed containers (with or
without compartments) that form the superstructure and are integral parts of the car. All such containers must be securely
attached to the underframe when offered for transportation but may have demountable features. Before any car can be considered
a tank car hereunder, the design of all such containers thereon must have been approved 1) by the AAR Committee on Tank Cars
as having met all applicable AAR specifications and requirements and 2) by said Committee or, in appropriate cases, the
Department of Transportation, as having met all applicable specifications and requirements of Subpart 1 of the Regulations of
Transportation for Explosives and other Dangerous Articles.
TA tank car (ICC 103 series)

Tank cars which were insulated with an outside jacket have an “I” after the code, such as TMI. Pressurized tank cars, with the distinctive bonnet instead of a dome, are TP and usually TPI. The ORER has a long table identifying these classes, along with the also-required ICC classifications. Thus for example, a tank car might be AAR Class TM, as well as class ICC 103, or AAR Class TPI and also class ICC 105A300. In addition to the information in the ORER, more about these tank car classifications and their cargoes is available in an appendix to Ed Kaminski’s book, Tank Cars, American Car & Foundry, 1865-1955 (Signature Press, 2003).
Tony Thompson

Class “X” – BOX CAR TYPE

XM – Boxcar for general service equipped with side or side and end doors
XF – Non-insulated boxcar similar n design to XM, designed and specially prepared with a U,S, Food and Drug Administration
approved white epoxy or other comparable white coating to seal interior walls, doors, and ends, and provide a smooth, durable
surface to prevent contamination.
XL – Loader equipped. Similar in design to XM, with steel perforated side walls or equipped with interior side rails for securement
of certain types of lading and/or permanently attached movable bulkheads. Note: Cars equipped with interior side rails only, built
new, rebuilt or reclassified on or after January 1, 1966, in order to qualify for the XL designation, shall have a minimum of four
(4) usable side rails on each wall of car, each extending from doorway to approximately four (4) feet from end of car, plus facilities
in doorway to accommodate doorway members. The facilities in the doorway are not required in cars equipped with plug type
doors.
XP – Boxcar similar in design to XM, but which is specially equipped, designed, and/or structurally suitable for a specific
commodity loading; except boxcars (XF, XM, XMI) dedicated to the transportation of commodities in Paragraph A,
Rule 97, AAR Interchange Rules, must be designated XP.
XA

There are a lot of box car classes. In the ORER, you will see box cars identified by a number of other codes than XM. The key to understanding these is to note whether there is an “M” in the class designation. When you see a class such as XAP for auto parts racks or XAR for automobile racks, that tells you that neither of these is usable for any other loading, which is why the “M” is missing. Also present are variations on XM, such as XMR and XME. These have “stowable” racks which can be secured out of the way and then can be used for other loading. Boxcar bodies with tanks for liquids inside are actually tank cars, and have the classification XT.
Even though the AAR did define any house car with double side doors as an “automobile car” in 1953, all boxcar-type house cars were classified together as various X classes, without directly distinguishing box and auto cars. Indeed, most railroads in 1953 rostered part of their double-door cars in general service and classed as XM. This is one example of why you might want to know AAR classes for your models: is that double-door car in automobile service or not? The AAR class shown in the ORER will tell you.
Tony Thompson

Class “MW” – MAINTENANCE OF WAY EQUIPMENT

MWB – Ballast Cars. All descriptions of cars used for the purpose of carrying ballast for the laying of new right of way and repairs.
The car used generally for this type of work is of the gondola type, with side or center dump.
MWC – Caboose and Tool Car. Similar to tool car, but having one end fitted up as a caboose, with bunks, stove and water storage,
with or without lookout, and is used in either work or wrecking trains.
MWD – Dump Cars. On the type of contractors’ car used for building up fills; the body of the car dumps being raised by means of
counterweight, air or hand power.
MWE – Ballast Spreader and Trimmer. A car with blades or wings for spreading or trimming ballast.
MWF – Flat Car. Used for transporting rails, ties or ballast and for storage of wrecking trucks, or gathering scraps along right of
way. These cars are at times equipped with low sides, about 10 or 12 inches high.
MWG – Section Gang or Track Inspection Car. Flat car, with or without seats or tool boxes, and equipped with single or double
cylinder gasoline engine serving as motive power.
MWH – Hand Car. This car is flat and mounted on four wheels and propelled by means of pushing, known as “Push Car.”
MWJ – Ballast Unloader. A car equipped with machinery for pulling a plow through cars loaded with ballast.
MWK – Snow-Removing Car. A car equipped with any special device for removing snow from between or alongside of rails.
MWL – Hand Car. This is a small flat car, with or without seats, mounted on four wheels and propelled by means of cranks or
hand levers.
MWM – Store-Supply Car. A car equipped for handling material to be distributed for railway use.
MWP – Pile Driver. A car equipped with machinery for pile driving.
MWS – Steam Shovel. Car equipped with donkey engine. Having a boom of wood or steel and the end of which is a shovel or
scoop. It may be propelled by its own power or by means of a locomotive and run as a car in freight trains, being equipped with
safety appliances. The cubic capacity of shovels, in yards, can be indicated by figures after the classification letters.
MWT – Tool and Block Car. A car used for the carrying all descriptions of tool equipment and blocking. This car has side and end
housings and roof, also end platforms. There are doors in sides and ends and usually windows. It is fitted inside with proper racks
and boxes for storage of tools.
MWTK – Similar in design to T, but used specifically in maintenance-of-way service.
MWU – Wrecking Derrick. This derrick has boom and hoist fitted to frame of flat car and lifting done by means of hand power;
propelled by locomotives.
MWV – Wrecking Derrick. This derrick has boom and hoist fitted to flat car and having drum at one end to furnish means of
hoisting; steam furnished to donkey engine, running drum, by means of flexible steam line from attached locomotive; propelled
by locomotive.
MWW – Wrecking Derrick. A derrick used for wrecking purposes having donkey engine to raise and lower booms and hoists;
engine housed in and on separate platform with boom, is pivoted in center of car frame in order that it can be worked on either
side or ends; usually fitted with anchor beams to be used for heavy lifting. Fitted with safety appliances and propelled by means of
locomotive. Lifting capacity in tons shown by means of figures.
MWX – Boarding Outfit Car. This includes cars used for boarding, sleeping or cooking purposes in construction and similar work.
Weed Exterminator. A car equipped with machinery for propelling itself, or otherwise, and burning or spraying weeds along the
track as it proceeds.
Ditching Car. A car equipped with machinery for propelling itself, or otherwise, and excavating ditches along the sides of the track
as it proceeds.
Rail Saw. A car equipped with machinery for sawing track rails and similar material.
Rail Bender. A car equipped with machinery for bending track rails and similar material.
Grass Cutter. A car equipped with machinery for propelling itself, or otherwise, and cutting grass along the track as it proceeds
Track Layer. A car equipped with machinery for propelling itself, or otherwise, and laying the track ahead of it as it proceeds.
*note there are many more subclasses. (*see NMRA ORER)

Class Numbering and Types

The classification remained the Harriman system of 1904, up to the end of the SP. As an example in that system, hopper cars were class H. The second part of the class number was the nominal capacity in tons, and modern coal hoppers would be 70-ton or 100-ton cars, thus H-70 or H-100. The final part is the chronological design number.
Tony Thompson

Pullman-Standard Freight Cars

PS-1s are box cars. (There is no such thing as a PS-1 covered hopper).
PS-2s were covered hoppers.
PS-3s are open top hopper cars.
PS-4 are flat cars.
PS-5 are gondolas.

Reference

Read Ed Kaminski's Pullman-Standard Freight Cars, 1900-1960.
Arved Grass

Southern Pacific Lines
AAR Freight Car Designations

General Information
Descriptive Designations
Class F flatcars
Class G gondolas
Class H hoppers
Class L special cars
Class MT maintenance-
of-way cars
Class N cabooses
Class R refrigerator cars
Class S stock cars
Class T tank cars
Class V ventilator cars
Class X box cars

Class Numbering and Types
Pullman-Standard Freight Cars