Agree most yards collect empties for repair and assignment, but then they are usually not located in what appear, in the photo, to be either arrival or departure tracks. For the Major roads, most WWII era yard photos I have seen set the repairs apart from the rest of the yard.
I'll wait for an ATSF expert to weigh in, but using Google Earth and a 1952 historic aerial, Barstow yard was much smaller than it is today (less than 1/3rd the size) and does not look like a classification yard. Not big enough. The aerials make the case that Delano was standing on the southern span of the road bridge spanning the west end of the yard and photographing to the east. The passenger train area was further to the left (beyond the trees) - was there a major Harvey house in Barstow? The 1952 aerial shows what may be eight passenger tracks with platforms, and a significant building just north of those tracks - about as far away from the engine facilities and shops on the south side of the yard as they could get.
The aerial suggest Barstow was too small for any significant classification during WWII - it looks more like a division yard with relay tracks for through freights. 16 tracks at most for freight, and no evidence of any significant yard leads or drill tracks. Just looks like a division point where locomotives and cabooses could be changed out and brakes tested. Assuming ATSF was right hand running at Barstow, the trains in the right foreground are EB, and with the significant traffic (load vs MT) imbalance that happened on both coasts during WWII, a string of ATSF MT's heading east makes a lot of sense.
But full disclosure - in defense of your view that these home road cars have been set out for loads, is that Yermo was one of three major war department staging areas for west coast shipments of material into the Pacific theater during WWII (the depot remains today). Yermo consisted of two depots, one about 5 miles RR east of Barstow, and another 8 miles RR wast of Barstow.
So all of those ATSF box cars would be empties waiting to pick up a load for the ports into LA, or, they could be loads coming out of the depot about to head for the ports. Either way, they would represent a train movement with box car consist significantly diverging from the N-G theory, if you are inclined to apply the theory to each train (as opposed to characterizing the average for a major route over a period of time - which is how I intend to apply it.)
This does remind me of the Delano photo of one of the Chicago yards with a long string of at least eight wooden box cars with big white X's painted on the doors - which indicated ammo (making it clear not to hump, and to park them away from people and critical facilities) - that string was 100% CNW.
---In STMFC@..., <timboconnor@...> wrote :
Almost any large rail yard will have strings of home road cars. They
could be (1) awaiting repairs or (2) awaiting assignment. They park them
together to keep them away from cars in transit. They are NOT a consist.