A somewhat famous "in-yard" reverse loop is on the west end of the now BNSF Barstow Yard. Right out there in the open. They don't even TRY to to hide it. Sure, they connected a few tracks here and there, but they're not fooling anybody - we know it's there. It just ain't prototypical. They don't be no purists, that's for sure.
A great, almost model size reverse loop is located at the intersection of 135th and Mozart streets in Chicago. While not in a yard, this loop encircles an industry - a good way to hide part of it. There is even a small stub-end sorting yard inside the loop. And it is nearby Blue Island Railroad Crossing, a very cool place. Slow trains & and some not so slow. Foggy, rainy, snowy, sunny, nighty. Ninety trains a day with engines wearing coats of many colors. Seven large bridges, one disused, crossing the Little Calumet River. Tracks coming from everywhere along with Broadway Street crossing at grade eight tracks AND tracks on an overpass - a real spaghetti bowl feel.
Check out this NMRA Layout Design 'Special Interest Group.
NOTE: This is not a hot link. Copy-n-Paste in the Google to get there!
https://ldsig.net/o/ldsig/wiki/index_title_Spaghetti_Bowl_Layouts.html
While I'm not a space cadet, the Jupiter Symphonyis jazz to me ears.
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The North Vernon Cutoff Loop is hanging off the edge. Having the open reverse loop high in the mountains allows for excellent views of trains, just as any great train watching spot should. This loop is 32, 55-foot cars in length. Longer trains must do some interesting switching in nearby Social Circle's tiny yard before clearing the loop. The train is just entering West Social Circle, where the main line passes within 15 feet of the backs of buildings of an artist conclave area including art shops, non GMO/gluten free eateries, galleries, and studios. Add in lots of pedestrian traffic that can be on or near the tracks. Slow speeds, lots of bell ringing and horn blowing helps the trains become noticed. Urban legend has it that paintings have actually fallen from gallery walls when "those darn noisy" trains pass by.
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On the trip down the mountains, trains often work in South Monroe. Here the train has left a cut on the main. The train has slacked off and started easing slowly through downtown Monroe proper. Waiting on the yard lead is a local crew ready to enter the main and couple up once the train clears the area. What is a boxcar doing in a hopper train? It is a block car. Instead of standing trackside looking for, and possibly missing, a particular car number as the train rolls by, the trainman just looks for the odd car and that is his cut. This is a trimming move required for the train to turn itself in Blueberry Yard.
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Blueberry Yard contains a cut-off track that was originally used to turn inbound steam locomotives arriving on passenger trains. The track was connected to an existing yard thoroughfare. Known as the 'slide,' this short steep (5% grade) track now allows inbound trains to change directions within yard limits. Then the trains can drill the old passenger thermal trackage, turned stub ended freight yard, seen in the distance. This loop is 22 cars long and the shorter length is why the trim move was made in South Monroe. If the trim is required to be delivered to Blueberry, the trim cut will be made there and worked by a yard job.
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And the final pleasantness of the "slide" is this train set under-n-over. It is important to include stories when designing. Folksy tails like in Photo 1, operating narratives as in Photo 2, sensible contrivances per Photo 3 and personal preferences no matter the oddity as in this photo. In old school reasoning, the development of story lines is most important - think avatars and RPGs.
I don't think a reverse loop within a single scene (your examples of Barstow, Chicago, or really any bulk product industry that accepts unit trains) is the same as a "spaghetti bowl" layout.
Looking at Barstow yard or an industry with a loop track, the majority of the track is linear.
It's really a simple concept - does the layout track plan have a bunch of seemingly endless overlapping loops? In other words, does it look like a bowl of spaghetti?