Model Railroading Gauge FAQ's

One of the most common questions asked by newcomers to model railroading is - What scale is best? Actually, they probably are asking - What size should I get? The answer, of course, depends on the individual. However, it is important to understand the sizes available in order to make that decision. Before beginning in the hobby, or for those taking the hobby to the next level, it is a good idea to familiarize yourself with the following Frequently Asked Questions. If the answer to your question is not here, then visit the Model Railroading Bulletin Board for a further search or to post the question for the experts.

What are prototype trains?
Generally, railroaders will refer to the real (full size) trains as prototypes. As the name implies, every track system is a unique, one of a kind system. Thus, prototype is a valid name for these trains. This also makes it easy for those immersed in the hobby to refer to the full size systems. Remember, the serious hobbyist’s desire is to create a "real" system of his/her own. Therefore, to refer to full size trains as the "real trains" is far too confusing.

What is the difference between toy and model trains?
While all trains may be considered toys, not all are considered models. The difference lies in the way the manufacturer has created the trains. Model trains are designed exactly as the name implies, that they are scale renditions of real (prototype) trains. Their dimensions are such that they closely replicate the originals. Toy trains are made without this same attention to replicating the details of the original, prototype train. This does not make one any better than the other. In fact, some of the most popular sizes of trains are considered toy trains (such as Lionel’s O Scale).

What is Gauge vs. Scale?
For model trains, gauge is the measurement between the two outside rails of the track. For toy trains, gauge is the measurement from the center of the two outside rails. Standard gauges have been agreed upon to identify these dimensions. Those gauges are usually referred to by a single (or in some cases two) letter(s). In general, gauge is referencing specifically to the track size used.

Scale is the fractional equivalent for the gauge. This fraction is actual inches as the numerator and original (prototype) inches as the denominator. Hence, 1/48 scale means that your scale model is 48 times smaller than the original (prototype). 1" on your layout equates to 48" on the original. Scale is also expressed as the two numbers separated by a colon. So, 1/48 scale can also be shown as 1:48. Scale is most often used to express the entire train layout, not just the size of track.

Below is a chart of the most popular gauges of hobby railroads around the world. 
However, some other sizes exist only outside of North America.

 

What is HI-Rail?
As with any hobby, some people are more purists than others. HI-Rail refers to the fact that Lionel O Gauge trains are not true to scale. Basing the O Gauge at 1/48 scale, and knowing the actual Lionel track is 1/4" high, you could discern that in full size, the Lionel track would be one foot high! Similar measurements of track width, wheel flanges, as well as the rail bed ties, would show similar disproportions. It is believed that Lionel knew full well of these irregularities when they first designed the equipment. But, for reasons of durability, ease of use, and the fact that miniaturization was not so easily manufactured back then, Lionel accepted these abnormalities. Some will refer to all toy trains as HI-Rail regardless of the track scale height.

Original Lionel trackside equipment was also made with great liberties to scale to enable it to be easily manufactured, easily handled by young hands (these are toys, after all), and ruggedly built. The HI-Rail name is often used to describe a whole layout that is not true to scale.

What is Proto-48 and how is it different from O Gauge?
Because the O Gauge was created as toy trains without specific attention to scale, a second 1:48 scale was created that is true to scale. This is called Proto-48. From the chart above, you can do the math to show that Proto-48 Gauge track will be 4 feet, 8 ½ inches wide. This is the proper width of standard gauge prototype track. (Please note that there are smaller sizes of prototype track often referred to as Narrow Gauge. We will deal with them later.) O Gauge, however, would solve to have track that is 5 feet wide. Thus, Proto-48 exists simply to make a "true" 1:48 scale available.

Is "Proto" used elsewhere?
Yes, there are other less common gauges that use the "proto" designation. Generally, it means that this track is the most true to scale for this size, i.e. Proto-24, or Proto-48,

What is Finescale?
Further, in the smaller gauges (HO and smaller), there is track available which is smaller than the standard gauges, but not quite true to (prototype) scale. These tracks are designated Fine scale, i.e. Ho Fine, S Fine, and so on.

What is Narrow Gauge?
Though seldom used on main lines, Narrow Gauge track was laid in areas where rail traffic was light, curves may have needed to be tight, and cost was a major issue. Thus, Narrow Gauge, as the name implies, track had a distance between rails of between 2 - 3 feet. Most popular in mining spurs, logging spurs, and scenic tourist rails, Narrow Gauge has a charm and characteristic very popular in Old West type layouts. There still are many prototype Narrow Gauge spurs in active use today. For modelers, the Narrow Gauge designation (a small "n" plus the prototype rail width) generally follows the Standard Gauge designation, i.e. Sn3 means S Scale - Narrow Gauge - 3’ Prototype, and HOn2.5 means HO Scale - Narrow Gauge - 2.5’ Prototype.

(Perhaps not) coincidentally, HOn30 is the same size as N gauge track. HO is the same as On30 which is O scale narrow gauge 30" between the rails. To be prototypical they should take out every other tie on the ready-made commercial HO track so it will look right in the larger scale (O compared to HO scale). Some enterprising railroaders will intermingle the track sizes on a layout. Then, they will simply replace the "trucks", or wheel assemblies, on the larger size cars to fit the smaller gauge track. Or, similarly, they will make the whole setup a Narrow Gauge system by doing the same.

Additional Information Links:

• www.nmra.org/beginner/scale.html
• www.spikesys.com/Modelrr/scales.html
• www.singlesorganizations.com/crazyabouttrains/modelrr.html

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