The most important goal of my model railroad design service is getting into my customer's head, finding out what their true interests really area, and then converting that to a track plan.
A very common example is somebody whose passion is freight cars...modern ones....long ones...and lot's of variety. Their space is on the the small to average side. They want something plausible.
Generally the first place they go is some form of continuous run format....which means curves. Small space, long cars, plausible....that combination won't fly. It ends up being the classic case of overreaching (part of every modeler's DNA), a case of trying to put 20 pounds of nails in a coffee can.
This is where the definition of a "good" design comes in. Remember at the beginning the person emphasized over and over their interest in freight cars. A little more questioning reveals that the continuous run aspect was more of an afterthought, nice to have but not crucial. With the shackles of continuous run removed, and along with that the need for curves, a world of possibilities opens up.
The prototype has designed just the thing for this person, the "Team Track Yard". This isn't a single track but an actual yard. (picking nits I'm going to make the distinction between team track yard and transload facility). Many customer's need rail service but don't have a siding. The solution, which railroads came up with a century ago (and still exists), is to bring the car to the team yard and then the customer can come pick it up. It's sort of like ordering a drill online from The Home Depot, getting an email from them when it comes in, and then going to the store to pick it up. Same concept.
Let's say their is a major bridge project in LA, something that requires massive steel beams, which are made in Chicago or Pennsylvania. It's not practical to truck those across the country. The steel fabricator, which has rail service, loads them on a flat, and then ships them to the team track yard in LA for the bridge contractor to come pick up. From that point it's a much easier job getting the beam across town to the jobsite.
The beauty of team tracks is that, even today, they take EVERY CONCEIVABLE car type. You name it: centerbeam flats, bulkhead flats, regular flats, plastic pellet hoppers, gondolas, coil cars, tank cars, boxcars, the list goes on.
Let's convert this to an actual design. You want plausible? How's this. I grabbed an aerial photo of BNSF's team track facility in Vernon (Los Angeles), and overlaid the track plan you see above. That's right, the plan above is an EXACTLY TO SCALE copy of the actual yard. The footprint is only 3ft. by 11ft (plus the need for staging or a switch lead). Turnouts are number 6's. The variety of cars going into this facility is staggering. From what I can tell it's generally switched by a tandem of GP-50's out of Malabar Yard.
Here's a map to show how everything fits together in context. Malabar is about two blocks to the west. LAJ's A Yard is to the east on the banks of the LA River.
This is a Bing Maps Birdseye view. The LAJ yard is just a few feet away but the two are not connected and are served from separate yards. If you want to find it on your own (online or in person) it's roughly at the intersection of Fruitland Ave. and Seville Ave. I've been there several times. It's a clean and safe neighborhood and not that far from LAX.
Looking through the gate from Fruitland Avenue. 2012. Check out the coil car!
Another view from Fruitland Avenue, this time in 2015.
A few twists on the plan...this facility has been around for ages. You could do a backdated version in a Santa Fe theme. If you had more space, you could link it to the Malabar Yard design I did awhile back and run transfers between the two. Although not specifically filmed at the team track yard (which isn't that visible from the street), there have been a number of great railfan YouTube videos of the general area.
The key to a successful model railroad design is getting in touch with your true interests (which is harder than you would think), and then being realistic about your real world resources of space, family political boundaries, time, and energy.