Here's a brief explanation of the 3RS concept.

3RS stands for "3-Rail Scale" and is primarily about the trains...the models themselves. 3RS is about building a model that is as faithful as possible to the prototype. If a 3RS model is placed beside a 2-rail model of the same locomotive, they should be virtually identical.

The 3RS forum is for discussions about scale locomotives and rolling stock. Discussing a model, and the ways the manufacturer and individual modeler can improve on it is the fun of the 3RS Forum. The 3RS concept doesn't get too involved in the layout or scenery but instead focuses on the trains.

The most basic features that differentiate a 3RS locomotive from a 3-Rail loco is the concept of fixed pilots and scale couplers. While this may not make a diesel a great 3RS model, it is the basic starting point to consider a diesel 3RS. The same holds true for a steam locomotive. Equipped with scale couplers, proper class lights etc., many 3-rail steam locomotives can be modified into a good 3RS locomotive. Equipping your rolling stock with scale couplers is a step towards 3RS.

But pilots and couplers are just the starting point. There is much, much more detail that can be added to make a 3RS locomotive, freight car or passenger car a very accurate model that is true to its prototype.

If you like this concept and this type of modeling, then the 3RS forum just may be for you! And if 3RS isn't your cup of tea, there are a lot of other forums here to catch your interest.