Two good questions to ask someone who perhaps is mostly known as a non-compromising rivet counter in 0 scale. But, as have been seen before, that view is an over-simplification as my railway and model railway interests span widely.
Actually, it is rather simple. Firstly, I started in N scale when I was 13. Few years before I had tried my hand on H0 scale, inspired by my fathers model railway in that scale, but I did never bring it far. I did that with my N scale model railway, though, as it lasted for 5 years until I moved on to 0 gauge. So I knew N scale and it's weaknesses but also some of it's advantages.
The fact is that 0 scale takes up a lot of space and that I may never have the room for a decent-sized 0 gauge layout. I do like to run the models but it must be in a prototypical way, and switching (shunting) must be possible. That was a problem with my old N scale models, they didn't run too well. But there have been quite a development in that area since.
I probably will hand-build some track and most turnouts and of course a layout but locomotives and rolling stock I prefer to buy ready-to-run. I think I can manage to change couplers and wheel sets and do some weathering, but basically I don't want to build it myself. Because of this the time frame chosen must be more recent than the one I have chosen for my 0 scale models so that the look of the models do not suffer much from the necessary oversizing of certain parts which is more obvious in N than in 0.
This is actually also rather simple. For a long time I have been fascinated with american railroads. This interest started, I think, when I read old copies of "Populær Mekanik" which my father bought, and I was a frequent guest on the library which also had some German, English and American books. This was a cause for learning foreign languages, too.
When I began earning my own money, I bought copies of "Model Railroader" and soon I subscribed, in fact I was a subscriber for around 20 years. Since then I have started another subscription but the magazine has changed quite a lot since I started reading it. Or perhaps it is just I who have changed.
What characterizes railroad transport in the USA are the long distances and the long trains. The passenger traffic is small compared to the freight traffic and is concentrated in certain corridors. It was not allways like that; in 1930 the passenger train mileage on AT&SF was around 50% of the total mileage. During the following years the passenger traffic declined steadily until all passenger traffic was taken over by Amtrak in 1971.
By chosing the area and time frame for the layout I want to achieve that
I chose the Atchison, Topeka & Santa Fe Railway as my prototype. Santa Fe is probably mostly known for its through lines from Chicago westward to Los Angeles and southward to Galveston, but the company also had a large net of secondary lines and branches in Kansas that are well suited as prototypes for model railroads. I chose the single-track lines (Chanute/Cherryvale)-Moline-(Winfield) and Moline-(Emporia) (Howard branch) as a basis.
The first diesel locomotives which had important impact on railroad traffic in the USA was EMD FTs from 1939. They soon took over traffic on desert lines because of the difficulties providing water for the steam locomotives. About 1950 a sufficient number of diesel locomotives had been delivered to phase out the last of the steam locomotives and in 1953 steam was in practical terms gone.
In order to be able to run the last of the steam locomotives, I chose the 1950-55 time frame where most locomotivs were diesels like EMD FTs, F3s, F7s og GP7s.