Thursday, March 21, 2024

Modeling SP Automobile Boxcars (Part 1) - SP 64931, A-50-14 by P2K-Walthers 50ft DD

SP 64931, A-50-14, by Proto2000/Walthers.

Life-Like's Proto2000 line (later taken over by Walthers) produced an accurate model of AAR automobile boxcar SP's 1941-built 50ft automobile boxcars of A-50-14 class in the 1990s.  

Left side of SP 64931, A-50-14 by P2K/Walthers

These models, both as kits and RTR, are fairly commonly available.  Also don't think that just because the car has "AUTOMOBILE" stenciled on the side, that they were only used in automobile service.

SP Roster History

SP 64210 unloading autos at Sonoma, CA in 1956 - Troy Marmaduke & Brian Biekofsky collection

Let's look quickly at the SP's progression of 50ft Automobile steel boxcars orders.  We'll start with the pre-war 1936/37 series, which roughly followed the early AAR standard designs of the time.  Note the square corner post in the photo of 64210.  Anthony Thompson's blog post on SP A-50-12 "Modeling pre-war SP 50-foot automobile cars" covers kitbashing an Athearn 50ft DD boxcar.  I may end up doing a kitbash for my own A-50-12 at some point.

A-50-12 - 50'6" Square Corner Posts (5/4 Ends "Dreadnaught" ribs by Union Metal Products)
SP 69530-70029 (500 cars) 10-12/1936
SP 64100-64924 (825 cars) 5-7,9,10/1937

SP 32892 B-50-18 RC Square Post Ends

These cars were built at the same time as SP B-50-18/19 class 40ft boxcars that had square cornerposts ends.  Likewise, they are probably better kitbashed by Athearn 50ft Double-Door Boxcars like Tony Thompson did in his blog post.

The P2K Model - A-50-14

Left side of SP 64931, A-50-14 by P2K/Walthers

By 1940 the next order of 50ft SP cars had upgraded to the standard W-corner post ends of the modified AAR boxcar design, more in line with the B-50-20,21,23 class cars.

B-end of SP 64931 showing W-corner post construction of the A-50-14 class.

A-50-14 - 50'6" W-Corner Posts (5/5 by Standard Railway Equipment Co.)
SP 64925-65424 (500 cars) Jan/Feb'41
These cars are the ones that P2K produced.

Post-War Auto-Part Cars

A-50-15 - 50'6" - Evans Auto Loader Equipped, Standard Railway Equipment straight-panel roofs (which look like the P2K roofs, not the diagonal panels of later cars), continued use of 4-6 side sheet pattern from pre-war cars, but riveted with ACR pattern, like the B-50-24.  These cars also used the 3-section doors with wide joints - like used on the B-50-24 class 40ft boxcars.  The ends are 4/4 Improved Dreadnaught ends, typical of post-war cars.
SP 65425-66174 (750 cars) 11,12/1946

The A-50-15 will be a tricky car to model with the combination of prototype details, if one has to be modeled, probably best to get a resin model of the class.

Accurail 5200-series 50ft Double Door Riveted Steel Boxcar (converted to B&W) seems to be a good starting point for the SP A-50-17s.

A-50-17 - 50'6" - Standard Railway Equipment Diagonal Panel Roofs (with or without 4 plain panels for Auto Loader racks). 1+3/4 Rib Improved Dreadnaught ends. Returned to single rivet rows and diagonal side-stiffener supports between the trucks.
SP 190000-190499 (500 cars) 9/1950-?/1950 Evans Auto Loader Equipped
SP 192000-192299 (1000 cars) ?/1950-5/1951 - 100 cars equipped with Evans Auto Loaders

Automobile Cars on the Jawbone Branch?

Standing on an SPNG boxcar at the Owenyo Transfer with SP A-50-14 (at right) with what appears to be loaded with rough freight - Rich McCutchan - owensvalleyhistory sp_narrow_g42c_sml

By the early 1950s, newer post-war boxcars were taking over most of the finished automobile loading, and auto-parts loading which were very specialized service assignments.  The prewar cars then joined the single-sheath cars in other services.  These older ex-automobile cars commonly went into finished lumber service out of the Pacific Northwest, many of them did not even have the "AUTOMOBILE" lettering painted over.  

1950 ORER Research

The ORER is really the best way to see which cars were still in auto service vs. cars downgraded to XM classification as standard boxcar service.  So I'll look briefly at the July 1950 ORER entry notes:

N = XMR 250 cars - Equipped with Evans Auto Loading Devices. Automobile position Interior Height 10'6" Loading Racks stored against roof Interior Height 9'8" (These cars were convertible from Automobile Loading Racks to plain XM-general service boxcar.)
(A-50-14-series) - (N1) 64925, 64926, 64929, 64930, 64932, 64933, 64935, 64936, 64938, 64940, 64941, 64944, 64947-64950, 64952, 64954, 64958-64961, 64963, 65966, 65967, 64971, 64972, 64973, 64975, 64977-64980, 64982, 64984-64988, 64992, 64993, 64999, 65002, 65004, 65005, 65014, 65015, 65017, 65019, 65022, 65027, 65028, 65030, 65033, 65035, 65036, 65037, 65040, 65044 ,65045, 65050-65053, 65057, 65058, 65062, 65064-65068, 65071, 65072, 65074, 65075, 65077, 65078, 65083, 65085, 65080-65093, 65097, 65099, 65101, 65106, 65107, 65109, 65115, 65117, 65120-65124, 65126, 65127, 65129, 65131, 65132, 65134-65138, 65145, 65149, 65150, 65151, 65158, 65162, 65164, 65165, 65169, 65171, 65173, 65174, 65179, 65182, 65184, 65185, 65188, 65189, 65193, 65196, 65197, 65198, 65200, 65202, 65203, 65204, 65207, 65209, 65210, 65215-65218, 65222, 65223, 65225, 65230, 65232-65235, 65237, 65239-65242, 65245, 65247, 65248, 65250, 65253, 65254, 65256, 65258, 65259, 65260, 65262, 65263, 65264, 65269, 65271, 65272, 65273, 65276, 65278, 65283, 65284, 65286, 65287, 65293-65296, 65298, 65302, 65304, 65305, 65310, 65312, 65314, 65315, 65318, 65320-65323, 65325, 65326, 65328, 65329, 65330, 65332, 65334, 65341, 65347-65355, 65357, 65358, 65359, 65362, 65363, 65364, 65366-65369, 65371, 65373, 65375, 65378, 65379, 65381-65386, 65388, 65389, 65390, 65392, 65394, 65400-65405-65411, 65412, 65414, 65415, 65418, 65421, 65424. 

O = Individual cars equipped for Auto Parts XAP 105 cars(3)
(A-50-12-series) - (O1) 64565, 64567, 64568, 64570, 64572, 64573, 64582,64587, 64589, 64593,64597, 64598, 64613, 64616-64620.
(O2) 64801, 64802, 64808, 64815, 64815, 64831, 64837, 64838, 64840, 64842, 64843, 64846, 64847, 64851, 64854, 64856, 64859, 64866, 64871, 64875, 64876, 64883, 64884, 64889, 64893-64896, 64900, 64901, 64903, 64906, 64912, 64922, 64924.
(A-50-14-series) - (O3) 64931, 64937, 64942, 64943, 64951, 64953, 64956, 64962, 64965, 64974, 65976, 64981, 64989, 64991, 64994, 64997, 65008, 65102, 65104, 65108, 65112, 65114, 65119, 65125, 65130, 65133, 65139, 65143, 65147, 65152, 65154, 65160, 65177, 65181, 65183, 65187, 65194, 65201, 65211, 65212, 65213, 65221, 65224, 65229, 65231, 65236, 65252, 65255, 65257, 66261, 65266, 65267, 65270, 65274, 65275, 65277, 65281, 65340, 65343, 65344, 65345, 65361, 65380, 65380, 65387, 65399, 65407, 65409, 65410, 65413, 65416, 65419/
(A-50-12-series) - (O4) 69840, 69855, 69860, 69865, 69878, 69880, 69883, 69885, 69890, 69902, 69907, 69909, 69911, 69914, 69916, 69923, 69925, 69931, 69933, 69936, 69937, 69939, 69942, 69943, 69948, 69949, 69951, 69952, 69956, 69968, 69973, 69976, 69998, 70002, 70003, 70006, 70011.

V = XAP 10 cars 
(A-50-14-series) - (V3) 64998, 65089, 65146, 65163, 65175, 65227, 65289, 65317, 65339, 65406. 
(A-50- 40ft cars) - (V4) 66194, 66196, 66199, 66202, 66209, 66216, 66219, 66225, 66226, 66238, 66246, 66258, 66262, 66263, 66269, 66279, 66287, 66296, 66304, 66307, 66308, 66322, 66324, 66326, 66334, 66346, 66347, 66348, 66382, 66388, 66404, 66407, 66408, 66411, 66426, 66428, 66429, 66571, 66579, 66586, 66587, 66595, 66599, 66612, 66526, 66629, 66651, 66660, 6665, 66669, 66673. (A-50- 40ft cars)

Y = (10 cars) - XM - not usable for automobile service.
(Y1) 63426, 63443, 63463, (A-50-12-series) - (Y2) 69695, 69714, 69789, 69803, 69967, 70021.

DD = Equipped for movable parts and suitable for handling auto parts, XML
(A-50-12-series) - 64525-64548, 64550-64564, 64625-64647, 64649-64713 (62 cars), 64715-64793, 63 cars in series 64927-65422.

JJ = XAP equipped for auto-parts loading (A-50-12) 64566-64924 series, 64800-64923 series
(A-50-12) - (JJ1) 64566, 64569, 64571, 54581, 64583, 64584, 64599, 64601, 64615, 64624.
(A-50-12) - (JJ2) 64800, 64809, 64827, 64830, 64832, 64833, 64835, 64853, 64855, 64861, 64864, 64867, 64869, 64881, 64888, 64891, 64896, 64907, 64910, 64923.

HH = Automobile Loading Devices, in Auto rack configuration 10'6".  When racks stored along roofs, lowered internal height to 9'8" 
* New cars being delivered. A-50-17 SP 190000-190499.
So this note applies to the whole class of A-50-17 as they were delivered.

DDD (A-50-12) - XMR except cars in series 69555-70029 and listed in Notes O, Y, FFF, & ZZZ.  Equipped with Auto Loading Devices. Automobile position Interior Height 10'4" Loading Racks stored against roof Interior Height 9'6" (These cars were convertible from Automobile Loading Racks to plain XM-general service boxcar.)

FFF = XAP Equipped for Auto-parts loading:
(A-50-12-series) - 64614, 64621, 64814-64911 (7), 69779-69997 (5), (B-50-22, 50ft SD boxes) 81529-81892 (10), (B-50-23, 40ft boxcars) 82323-82426 (3)

RRR = XMP equipped for truck loading devices
(A-50-12-series) - 64100-64524, (except 64329) and (A-50-12-series) - 69530-69554 for Truck Loading Devices, lowered IH 10'4", rasied collapsed against roof IH 9'6".

YYY = 750 cars XMR 65425-66174 (A-50-15) Equipped with Auto Loading Devices. Automobile position Interior Height 10'6" Loading Racks stored against roof Interior Height 9'8" (These cars were convertible from Automobile Loading Racks to plain XM-general service boxcar.)

ZZZ = Individual cars XM class in (A-50-12-series) - 69855-70025 series NOT equipped with Auto Loading Devices.
69855, 69856, 69857, 69858, 69860, 69861, 69862, 69863, 69865, 69867, 69868, 69872, 69873, 69875, 69877, 69878, 69896-69899, 69901-69904, 69907, 69909, 69911, 69912, 69914, 69916, 69917, 69923, 69925, 69930, 69931, 69933, 69934, 69936-69939, 69942, 69943, 69948, 69949, 69951-69953, 69976, 69977, 69983, 69984, 69987, 69988, 69990, 69993, 69996, 69998, 69999, 70002, 70006, 70007, 70011, 70014, 70018, 70022, 70023, 70025.

Special Service by Customer/Service

SP 3696 leads AW-7 with auto-parts block departing Bakersfield on January 7, 1953. - Note the Automobile cars unloading on the ramp in the right side of the picture too.

By April 30, 1956, the A-50-15/17s were assigned to Auto-Parts loading as follows (see Tony Thompson's SP Freight Cars Vol3 Table 7-3 on page 140 for individual car numbers).  I'm not going supply the number of cars assigned to each service.  Some cars were already renumbered to special assignment series.  Notice that the newest cars were assigned to the premier parts traffic and completed automobile shipments.

XAP -Body Decks-
Ford - Buffalo to Milpitas, Califorina - 60 cars assigned to Wabash (All A-50-17)
Cleveland - 118 cars (All A-50-17)
Lansing - 114 cars (All A-50-17)
St. Louis -39 cars (All A-50-17)
Ionia - 32 cars (All A-50-17)
Plymouth - 30 cars (All A-50-15)
Flint -27 cars (All A-50-15)

Note: Some cars were fitted with raised roofs and noted by car number in the 7-3 Table by 1956.

XAP -Engine Racks-
Chevrolet - 94 cars (most A-50-15)
GMC - 2 cars (both A-50-17)
GMC/Ford Machinery - 3 cars (most A-50-17)
Buick - 48 cars (most A-50-17)
GM - 4 cars (All A-50-15)
Pontiac - 44 cars (All A-50-17)

XAP -Other-
Top Container, Fisher - 34 cars (A-50-17, plus 9 B-50-36)
Steering Gear, Saginaw - 8 cars (A-50-15)

Transmission - 51 cars, as follows
Buick - 16 cars (mix of A-50-15/17s)
Chevrolet - 9 cars (A-50-15, plus renumbers?)
Detroit - 26 cars (all renumbered series)

To Stripe or Not To Stripe?

Technically the SP 64931 is an XAP car, and should be used for the specialized autoparts loading.  Most of the Proto2000 chosen car numbers for these cars appear to be XM (general service boxcar) assigned in 1950.

I may do some minor changes of this car number to make this car more correct to line up with the 1950 AAR car classification, to use this car as a convertible Automobile car with collapsible automobile loading racks as an XMR type car, and not make it an autoparts car.  The XMR would be more useful for the Jawbone Branch, both 64930 and 64932 were XMRs in 1950. 

X31F, PRR 81348, with door stripe for "AUTO RACKS" & assigned service stencil between reporting marks and AUTOMOBILES stencil.

The XMR cars, like PRR 81348 have the door stripe with tab and the stenciling for the Auto Racks, which my SP A-50-14 should have when I change number.  The stock P2K car is correct as an XAP class car, that would be for autoparts (body panels, etc), without a door stripe.

In Closing

I'm not planning to model any of the post-war SP Automobile cars any time soon, as I'm not modeling any section of the auto-parts/automobile pool routes between manufacturing centers and the assembly plants on the west coast.  I'll probably finish the cars that will be used in general service and lumber service, which would mostly be the general service A-50-12 and earlier class composite cars and the A-50-14s that were not in auto-service, or that were XMR equipped for dual service. - These cars were made available if extra automobile rack cars were needed, but otherwise would fill in SP's general freight needs, especially in the seasonal lumber trade, often moving finished lumber.

SP 64931, A-50-14 P2K model, note the chalk marks for SP AE-ATSF APE/ATSF 59-SP AW loading cycle for autoparts.

The Jawbone Branch really will only use the odd 50 foot double door car in XM service, aka, general service or lumber service, although the only cars seen at Owenyo when lumber was on the transfer decks were B-50-series single door 40ft cars.  So I'll probably only have one or two 50ft DD cars in the staging yard when the Jawbone Branch gets into service.

Jason Hill

Related Articles:

"Modeling pre-war SP 50-foot automobile cars" - Anthony Thompson's blog post on SP A-50-12.

Freight Car Overview Index - One page with links to all my modeling blogs on freight cars.

PRR Automobile & Parts Boxcars

Wednesday, March 20, 2024

Consist Photo Analysis (Part 6) - SP 4203 XMUG Mty Lumber Train - June 1950

Last time we looked at the SP's loaded lumber symbols (OCM & PSS) in "Consist Photo Analysis (Part 5) - PSS Lumber Symbol as Fourth-806 - June 1950", this time I want to look at the trains which returned those empty lumber cars back to northern California and Oregon, the XMUG.  Basically, the XMUGs were built at Los Angeles Yard (Taylor) with empty cars meant for north of Roseville, and could expect not to be switched out until Eugene.  This photo by William J Pontin shows there's a couple of weird cars in the train, but generally I believe this is an XMUG going to at least Roseville, if not beyond.

SP 4203 leads a long string of empty lumber cars down the north slope of Tehachapi into Caliente. - William J Pontin photo, Jason Hill collection

The XMUG symbol freights could easily exceed 100 empty cars, often running 120+ cars.  Minimal help would be needed for these trains westward to Bakersfield, outside one helper engine to Vincent Summit and one engine from Mojave/Rosmond to Tehachapi Summit.  I doubt there's any helper in the back of the train in the above photo at Caliente, which is almost to the bottom of the north-slope grade.

Of the 22 cars visible in the photo, there could easily be another 100 cars behind it, so we're probably only getting a sample size of 1/6th of the train here.  Even given the small sample size, there are some interesting cars to notice here, which raise a few eyebrows.

SP 4203 crosses Caliente Creek. (All cropped photos of main photo, same credit)

Car 1 - CNW steel 40ft boxcar.
Car 2 - Foreign 60ft flatcar, but not SP F-70-3 - as it doesn't have standard SP odd-spaced stake pockets.  Possibly a pre-GSC standard design, but those I don't think GSC-standard cars were built until 1953-54+.

Car 3 - SP F-50-16 with odd-spacing of the stake pockets between the trucks and endsills.  Interesting to see that this car is already heavily weathered in only one year! - SP 140234 is my model kitbashed from Red Caboose/Espee F-70-6/7 kit.

2nd cut of cars.

Car 4 - GN 40ft boxcar with Superior doors
Car 5 - SP 40ft Double 8ft Door Automobile Boxcar - without door stripe, so this is an XM boxcar, typical of lumber loading on the SP. - These are available in resin, but no plastic is really suitable to kitbash one from.
Car 6 - WP? 40ft boxcar maybe... This car's pushing towards too dirty to really see who owns it.

Car 7 - SP A-50-5/6 without end door.  Fairly freshly repainted and clean.  These cars were commonly used in lumber loading once superseded in automobile loading.  T&NO 58448, A-50-6 - Paul Doggett model & photo.  I have examples of these cars to build from the resin kits, when I build them, I'll make some blog posts.

Car 8 - SP F-50-5/8/9/10/12, 40ft Flatcar with sub-deck blocks are visible when zoomed in on. - OwlMtModels #2002 kit of F-50-5/8/9/10/12 class car.

3rd cut of cars.

Car 9 - Seaboard 40ft Double door boxcar. - It is interesting that this car is heading west towards Oregon with the rest of this empty lumber train.  In the small lettering over the herald these cars were stenciled "Furniture Automobile".  Was this car authorized for reloading on the west-coast by the SP and planned to be a long-range "roller" back towards home-rails?  Maybe in East-West Lumber/Furniture trade or sudo-pool arrangement between Seaboard, T&NO, and SP?  Accurail 40ft DD model, stock roster photo circa 2011.
Car 10 - Unknown 40ft boxcar with heavy weathering.
Car 11 - Either GN or maybe CNJ Single-sheath 40ft boxcar.  I think that's a goat herald, so probably GN car.
Car 12 - CB&Q - Looks like a WWII Emergency Boxcar or some 1920s USRA/clone style car, I'm not sure what reporting marks, although the plaque on the door below the tack board suggests possibly this is a Q-car "Burlington Route".

4th cut of cars, note the mostly cleaned decks of debris.

Car 13 - SP F-70-3 60ft flatcar. - I believe this car's longer than 53'6", and has the SP-style stake pockets.
Car 14 - Foreign flatcar - unsure, but probably 53'6" flatcar with very steep fishbelly slopes.  Maybe GN?  Possibly AAR, but weird angle to tell.

Car 15 & 16 - Probably SP F-50-11/13/14 class 50/52ft flarcars or maybe CB&Q or NP.  Several Pacific Northwest railroads owned ~50ft 50-ton flatcars, of similar late 1920s design, so I'm not going to try to nail down which exact cars these are. - Model is kitbashed Tichy USRA 40ft flat into 50ft flat, stand-in for SP F-50-11.
Car 17, 18, 19 - No way we can see what these are, but I think they're 53'6" overhanging deck flatcars.  So could be SP F-70-2/5/6/7 class, or 50-ton 53'6" AAR flatcars.

5th cut of cars.

Car 20 - NYC double-door auto-boxcar.  Like Car 9, this is a weird place and direction for an NYC car to be running empty.  Again, the XMUG routing would put this car north of Roseville and into Eugene yard before it would be switched out, so this can't really being a empty car going back to the Bay Area auto loading.
Car 21 - Obviously a 40ft boxcar wood running board puts this before circa 1940 built.  I can't quite make out the reporting marks on this car.  It's obviously a tall car, so pushing 10'6" or 11'+ car.
Car 22 - GN 40ft single door boxcar with square-panel roof.

Apologies that I'm not fully versed in the nuisances of all the possible foreign cars in the photos.  If anyone reading this recognizes specific cars feel free to comment below what they are.  Please include what car number in the train is the one that you're providing information about, and I'll be happy to edit the post to reflect the provided information.

In Closing

Once the XMUG reaches Bakersfield, the big AC 4203 will cut the crossing, and then be cut off and serviced at the roundhouse.  A freshly serviced 'Deck' 3600-class 2-10-2 backs down to the first section of the train and will take over for the run to Fresno and Roseville.

Bakersfield Yard with No.785 on Track 2.  Cutting the crossing at Haley St. this XMUG is getting ready to leave, circa 1951/52 - (Cropped) - Jason Hill collection

The typical photo showing the mix of empty flatcars and boxcars, which is the main signature for the XMUG for over 30 years.  In later years, the XMUGs often were mostly just flatcars or bulkhead flats... but in the post-war years and into the 1950s, these trains ran with a mix of car types.

Check out the previous post Consist Photo Analysis (Part 5), where I have more information on some of the options for HO models of the cars seen in that consist, which also appear in this photo too.

Jason Hill

Related Articles:

Monday, March 18, 2024

Consist Photo Analysis (Part 5) - PSS Lumber Symbol as Fourth-806 - June 1950

It's mid-June 1950, summer's come to the Tehachapi mountains.  This day it would appear that Fourth 806 is a PSS or OCM (use this link to see Eastward Through Freight Symbol List blog post) symbol freight charges the north-slope of Tehachapi Pass out of Caliente.  These two photos by William J Pontin provide a great view for us to analyze what cars typically were run in this symbol. 

SP 4274 leads a PSS-symbol freight around the Caliente Horseshoe, June 1950. - William J Pontin photo, Jason Hill collection

The signature cars of the PSS/OCM symbol trains is the large portion of the train moving lumber and forestry products from the Oregon Division (Eugene Yard) to either Los Angeles (OCM) or to points east of El Paso (PSS).

Rear two AC-class engines shoving hard on the rear of the same train, June 1950. - William J Pontin photo, Jason Hill collection

Looking at the second photo, this train certainly qualifies as either PSS or OCM with the large number of SP flatcars of lumber, GN, UP, and NP boxcars.  The GS gon with the scrap and a couple auto-boxcars it's possible this is OCM, but 75 years later, there's no way to really be able to tell for sure.  Obviously the exact consist would change day to day, but looking at multiple photos of similar consists for the trains and knowing what each symbol freight should be carrying from the SP's System Freight Schedule, we can make good educated guesses as to what we're seeing in a given photo.

I've covered an similar SP lumber train consist from 1947 near Oakridge in my blog post: Open Loads (Part 5) - Lumber Loads on Flats & Gondolas.

Details of the Forth-806 Consist

Let's look closer at the consist by cropping and zooming in on the photos.

SP 4274 in charge of Fourth 806 - note the small tab of the "4" in the indicators.

The SP 4274 certainly doesn't know that in a short seven years she'll be in the lime light pulling the last passenger excursion on Donner Pass.  Today, however, she's just another of the 195 modern AC's pulling a third class train in the SP's vast network of freight symbols.

The first group of cars in the train.

Cars 1 & 2 - This first group of cars look like a two single-sheath boxcars (maybe SP B-50-8/10/11/13/14s)
Car 3 - Looks to be a single-sheathed 50ft double-door or door-and-half car, possibly SP, GN, NP, etc.
Car 4 & 5 - A couple of 53'6" flatcars with lumber, probably SP 70-ton F-70-series. Car 4 might be a NP AAR 53'6" 50-ton car.
Car 6 - Seemingly empty SP G-50-13/14 gondola. - I'm not sure why this empty is being moved in this train.  It could be a car that was needed down in Los Angeles, note that this would be a vote that this consist is the OCM, not PSS.  I suppose it could be moving some sort of dense load, maybe steel, which would still be a little weird coming out of the Pacific North West... Maybe aluminium structural shapes?  Normally, the PSS-symbol wasn't switched out at Roseville, but I suppose this could be a Northern California fill to the train on the head-end.  If this was part of a Roseville fill, then it could be steel out of Pittsburg, CA steel plant.
Car 7 - A steel boxcar with Superior doors...

The second group of cars in the consist.

Car 7 Continued - The I'm not that familiar with the herald of this car, maybe Monon? -Leave comment below if you know what this car is and I'll edit the post:
"Car 7 is a puzzler... it looks like part has been cleaned or repainted and the angle of the light accentuates/obscures the paint and stenciling. I'm gonna noodle on that one for awhile." - Ted Culotta comment.
I'm thinking this could be an earlier Monon car.  The model photo I'm using here is a roster shot of a Kadee PS-1, NEW 1952, so obviously too new for the 1950 photo, but I'm guessing another of the Monon's cars from an earlier date.
Car 8 - Simple sheath boxcar looks like it might be a CNW car with a "Route of the 400" slogan, possibly a War Emergency car. - Model photo from IMRC website - fair use.
Car 9 - This boxcar is obviously an NP steel boxcar, with a Superior Door. 
Car 10 - Probably an SP G-50-18/22 class GS gondola with some low load inside, maybe bridge beams or other partial load that stays below the five foot high sides of the gondola.

The third group of cars in the consist.

Car 11 - "EJ&E (rebuilt 40-ton USRA double sheathed" - From Ted Culotta comment.
Car 12 - Then the double door car is a CB&Q automobile car with full size double-8ft doors. 
Car 13 - Another 53'6" lumber flatcar with SP-style stake pockets, which makes this SP F-70-2/5 class probably with SP initials, not the spelled out lettering of the -6/7 classes.
Car 14 - Looks like a classic UP B-50-series single door all-steel car.
Car 15 - "L&N (rebuilt ARA design single sheathed car)" - from Ted Culotta comment - Neat to see "random" east coast foreign cars showing up in this train symbol.

The fourth group of cars in the consist.

Car 16 - Another SP GS Gondola, G-50-18/22 class.
Car 17 - Looks like a steel-resheathed SP B-50-15/16 class car.
Car 18 - SP G-50-9/10/11/12-class GS Gondola with steel pipe load.
Car 19 - SP G-50-9/10/11/12-class GS Gondola with what appears to be a scrap metal load.
Car 20 - USRA 40ft single-sheath boxcar.  I'm not sure, the car has a painted door, but this paint scheme might be one of the CoG boxcars with painted door - but inversed contrast?  Oddly, I can't really see anything around where the reporting marks should be.

The fifth and last group from the head-end photo.

Car 21 - SLSF 147000-149499-series with wood door and Murphy ends, based on the data from my 161500-series car kit from Sunshine & comment "Frisco 'Howe truss' single sheathed car" - from Ted Culotta.
Car 22 -  IC double-door boxcar.
Car 23 - Another UP single-door 40ft all-steel boxcar.

This wraps up the first part of the consist from the head-end photo.
While I can't tell which engine this is helping, it certainly is opening up the throttle to climb the grade, as the exhaust bellows out.  Because I can't tell how many cars are in the consist between the head-end and the second photo, I'll assume that the second photo starts about where the 1st helper would need to be in the train.
First group of the rear helper photo.

I'll say that the car ahead of the 1st helper is the 27th car, but this is completely an informed guess based on tonnage of engines in the train, etc.
Car 27 - Probably SP B-50-8/10/11/13 class single-sheath boxcar with wood ends. - I'll have to refresh myself on which way the end-braces went on these cars to be more precise.
1st Helper - AC-10/11/12 class.
Car 28-30 - Unable to tell, but has Murphy ends, so could be USRA or all-steel rebuild of USRA car.
Car 31 - Looks like a steel 40ft car, but shorter than Car 30, so I'm guessing PRR X29 or maybe ARA '32, NYC boxcar, etc.
Car 32 - SP A-50-14/15-series double-door all-steel boxcar.

Second group of cars behind first helper.

Car 33 - SP F-50-11/13/14 50-ton or foreign 50ft straight-sidesill flatcar.
Car 34 - SP F-70-6/7 class 53'6" flatcar, as it does have proper stake spacing, nice lumber load!
Car 35 - SP B-50-13/14 with steel ends, without A-end lumber door.
Car 36 - SP G-50-13/14 50ft gondola with lumber load. - Same as Car 6.
Car 37 - foreign 40ft fish-belly side-sill flatcar with lumber load.
Car 38 - SP F-50-4/5/8/9/10/12 40ft flatcar with lumber load.

Third group of cars behind first helper and second helper.

Car 39 - MILW 40ft single-sheath automobile boxcar - with automobile loading rack door stripe.
Car 40 - UP 40ft double-door all-steel automobile boxcar, with door stripe indicating that the car has Evans auto-racks inside.  Notice that this car has double 6ft doors, not larger like SP preferred.
Car 41 - Heavily weathered Steel 40ft boxcar, possibly CP mini-box as the door looks possibly narrower (5ft), lots of chalk marks or fresh re-weigh stencils along the frame.
Car 42 - SP B-50-15/16 class boxcar, probably re-sheathed as all-steel.  This car is pretty weathered, as the herald is heavily obscured, but the reporting marks have been freshly restencilled or wiped off. - same as Car 17.
2nd Helper - AC-10/11/12 class.

Fourth group of cars, and last group behind second helper.

Car 43 - GN Plywood boxcar with ply-metal/Youngstown lower panel combo-door. - Not sure of details
Car 44 - GN plywood boxcar with Superior door. - Not sure of details
Car 45 - NP 40ft steel boxcar.
Car 46 - GN 40ft steel boxcar with Superior door. - Not sure of details
Car 47 - SP B-50-8/10/11/13/14 single-sheath 40ft boxcar.
Car 48 - SP standard cupola caboose. - Not sure if C-30-series or C-40-1/2/3.

Examples of Models

A few modeling examples in HO for typical cars of this consist, while this isn't an exhaustive list, I wanted to hit some of the highlights. - I may edit this when I take a few more photos of cars I have that would work in this symbol train.

NP Double Sheath Boxcar
While not specifically found in this consist, these cars were typical on the NP and could easily show up.

Weathering NP 11661 - A Rapido Double-sheath Boxcar - Basic weathering and finishing for service.

I also have an NP War Emergency 40ft Boxcar from Sunshine Models resin kit to build at some point, it would obviously be assigned to this type of service.

NP AAR'37 Steel Boxcar
NP 17182 - AAR'37 Branchline Yardmaster kit

Two of this car type are visible in the consist.  IMRC has also made models suitable for this prototype, so these cars are pretty common by 1950.

GN AAR'37 Steel Boxcar
GN 11869 - IMRC AAR'37 boxcar kit

Several of these steel boxcars are shown in the consist.  It's very nice to see multiple of the GN plywood boxcars in this one consist.  It shows there was substantial interchange between the SP and GN for the lumber traffic, not just the "friendly" interchange with the NP.  In this consist, it seems that the numbers of UP, GN, and NP cars were about even.

GN Plywood-Side Boxcar
Plywood GN 10784 from IMRC with Youngstown Doors.

These GN plywood-sided boxcars seem to show up regularly now that I'm looking for them.  This consist shows one of each of the other door versions (Superior & Youngstown/ply-metal), but not this exact one with the full Youngstown style door.  Sunshine has produced the other versions of this car with the other doors, and IMRC's more recent releases have the other doors as well, my car just happens to be an old run model.

SP F-50-5/8/9-Series 50-Ton Flatcar
SP 38892, an OwlMtModels #2002 kit SP F-50-5/8/9 class flat car with OMM #3004 Lumber Load kit

In 1950, the SP also had declining ranks of the class 1910s and 1920s built 40ft flatcars (Car 38 in this train) which numbered 2650 cars when new, and lasted well into the mid-1950s before fully replaced by the new 70-ton flatcars on the SP.

SP F-70-2/5/6/7/10-series 70-Ton Flatcar
EspeeModels/RedCaboose SP F-70-10 (-6/7 similar but riveted), with OwlMtModels 3003 Lumber Load kit.

The SP rostered over 2000 of these 70-ton flatcars by 1950, with another 1000 -10 welded cars coming in late 1953-54.  These and preceding classes of SP flatcar were staples of post-war building boom in California.  I've already posted an Index of SP Flatcar Classes, which covers this topic in more detail.

SP GS Gondola - Postwar G-50-18/22
SP G-50-18/22 class steel GS gondolas by Red Caboose, with scratch-built bridge beam load.

The SP in 1948 and 1949 took delivery of 2500 new steel General Service Gondolas, adding to their vast collection of earlier GS gondolas dating back from the 1920s.  Many of these steel gondolas were used in lumber loading, but also with other open loads such as scrap and new steel pipes, (as shown above Cars 10,16, 18, 19) in both the 1920s and 1948/49 groups.

SP G-50-13/14
Speedwitch G-50-13

The SP's small fleet of 50-ton 50ft gondolas are represented twice in this consist, which shows that they certainly were used in lumber service, as well as by the steel industry in the Bay Area.  Thankfully these cars can be modeled, either in resin or by kitbashing P2K/Walthers 52'6" Greenville cars by cutting them down to length from the center and also removing the fish-belly sidesills, and adding fishbelly centersills and Dalman Two-Level trucks.

SP B-50-15/16 Late-1920s Single-Sheath Boxcar
Rapido SP B-50-15/16 with steel sheathing, two in this consist at least.

While I'm not going to discuss all of the SP boxcar types here in this quick snap-shot, I have multiple posts about the topic, SP single-sheath and replacement steel-sheathed cars make up most of the SP boxcars in this sample train from 1950.  Showing that the newer B-50-25+ postwar, and even the B-50-18-23 class pre-war cars were not pushed down to moving lumber or forestry products yet.  Although, I would think that the newer classes of cars would be used for paper and news-print loads, but we happened not to see any of those in SP cars in these two photos.

SLSF 147000 & 161500-series "Howe-Truss" Single Sheath Boxcar
SLSF 147000-149499-series (wood doors, Murphy ends) from Sunshine Instruction Sheet - Fair Use.

The SLSF 147000-149499-series car is an interesting one to model.  The choices are somewhat limited. - Sunshine Models Resin or Accurail 6-panel boxcar would work well for modeling this car.

SLSF 161500 Sunshine carside & Dreadnought end castings from #39.4 kit.

Thankfully I have a Sunshine #39.4 kit which is one of these cars, but the details aren't exactly right for the car in this set of photos.  The kit I have is for the later series with Dreadnought ends and Youngstown doors, with steel sheathing replacing the wood sides.  While the earlier 147000-series, I believe, is the one in the photo which had the Murphy steel ends and wooden doors.  Because Sunshine is out-of-business/production, I'd have to start hunting for the 147000-series car kit if I wanted to model the exact car.

The other option is to start with an Accurail car.  Getting the wood-door version from their 7000 or 7200-series 6-panel boxcar kit and decalling it.  Sadly, the Accurail cars have full Dreadnought ends, not the earlier Murphy ends.  Tichy makes the Murphy ends as spare parts for their USRA boxcar kits, or I could reuse the ends from the earlier 4100-series Accurail kits which have them.  I'm already planning to replace the 4100-kit ends with custom ends for my SP B-50-13/14 series cars.  So I'll probably have some second hand Murphy ends to kitbash the Accurail 7000/7200 kit with to make the SLSF 147000-series car.  If I were going to do the Accurail 7000/7200 kitbash from scratch without a parts stash, the Tichy ends would be the way to go, I think.

Whenever I get around to doing either version, I'll do a blog article on it here.

In Closing

Next time we'll be looking at the XMUG, which is the flip-side of the PSS/OCM car movement flow.

XMUG-7 rolls through Tehachapi in 2018. - Jason Hill photo

I always enjoy looking at SP lumber train photos, because the individual cars in the trains builds an understanding of what cars would make up the majority of such train consists.  In HO scale, I don't believe that most modelers will be able to model an exact 50-70 car freight trains, but if we know what types of cars should be in the train, we can stage and route the layout traffic to form these types of consist.

Jason Hill

Related Articles:

Open Loads (Part 5) - Lumber Loads on Flats & Gondolas - SP Lumber Train 1-671 near Oakridge in 1947.  I also cover the consist in this photo in the linked article.