I would introduce to you guys the video series (YouTube) of "Rails Americana" below.
https://www.youtube.com/channel/UCf16gEGdbtIUgKq_mojD6gAEnjoy and please be a follower if you like it.
It contains right now 22 full size (3 to 5 min.) movies plus some shorties, and will continue up to 50 issues. It is pictured in a large HO scale layout called Denver & Green River Northern (D&GRN) located in the basement of Mr. Kenichi Matsumoto home in Tokyo, Japan. He is a NMRA permanent member and a famous layout builder. He also was the originator of a model RR magazine in Japan and loves G&D layout by John Allen since his very younger age. In fact he recently repaired some burnt locos owned by John Allen, and one of them is displayed in the RR museum in Sacrament, CA.
The outline of D&GRN:
Layout size: 42-1/2' x 22-1/2' (12,960㎜ × 6,870㎜)
Grade: 20/1000 standard and 25/2000 at maximum
Min. radius: 914mm
Hand laid rail is applied throughout the layout.
This is still under construction since 1977.
Ryoichi