What is 3-Rail Scale?
3-Rail Scale is an approach to model railroading that strives to achieve the most true-to-prototype realism possible with locomotives, rolling stock, paint schemes, scenery, operation, and other aspects of the hobby within the context of using 3-rail O gauge track.
Regardless of the scale you choose, be it 1:48 on the North American continent, 1:43.5 for France and the UK, and 1:45 for Germany and Switzerland, the overall idea is to get as close to the prototype as you can in your pursuit of the hobby with the talents you possess. This would include but not limited to the use of scale couplers, and other conversions that make the model as close to prototypical as possible.
3-Rail Scale is an attitude toward the O gauge hobby that derives satisfaction and fun from using the prototype as its guide. The intent in 3-Rail Scale is to continually strive for as much prototype realism as possible within the limitations of time, talent, and available space.
More than any other single thing, the desire for realism in miniature distinguishes 3-Rail Scale from other segments of the 3-rail hobby.