Size does matter - selecting a modeling scale

You've decided what you want to model and you know the size of the layout location. There's one more decision yet to make, and it's one that will affect your model building purchases for quite some time. You need to decide on what scale to use in your model building.

Scale vs. Gauge

First of all, there is one important distinction to learn, and that's the difference between scale and gauge. In short, these two terms can be defined as follows:

Scale

The ratio of miniaturization of an object.

Gauge

The distance between the rails on a section of track.

It may be easier to think about the difference between these two terms by thinking about their effect on a model person populating your model railroad. The scale of the model railroad will affect how tall a person stands, while the gauge will have no effect on how tall a model person stands. Most railroads operating today use standard gauge as the spacing between the rails on their tracks. Generally, this works out to a rail spacing of 4 ft, 8½ in (1435 mm). But, prototype railroads throughout history have used different gauges, especially in the early 19th century before standard gauge was widely adopted. No matter the gauge a railroad used, be it 2 ft, 3 ft, or even 6 ft (as was seen on some early Russian railroads), a 6 ft tall person will still stand 6 ft tall in your selected modeling scale.

Popular model scales

The NMRA specification for standard model scales is documented in S-1.2: General standard scales. While there are other scales that are used for modeling (such as G, 1:24, and 1:200), this document contains the most common scales that you are likely to find at your local hobby shop. The most popular model railroad scale right now is HO scale; this generally works out to a 1:87.1 ratio of model to prototype sizes. A 6 ft tall person in HO scale would stand at 0.83 inches tall. N scale is currently the second most popular model scale, which is measured as a 1:160 ratio. The same 6 ft tall person stands 0.45 inches tall in N scale. Along with the size of a person and potential modeler eyesight issues, another major determining factor in selecting a scale will be the minimum radius of a circle of track in each scale. In HO scale, 18 inches is used as a normal minimum radius, while in N scale, 9¾ inches is often used as a minimum radius. Larger scales, naturally, have a larger minimum radius (24 inches is common in O scale, for example). Trains will simply not operate well on radii tighter than the minimum radius in each scale, but wider radii will not only allow you to operate larger equipment on the same track, the equipment will also look quite a bit more realistic on broader curves.

Which scale for you?

There is no "best" answer in all cases. The most common answer is HO scale due to its popularity, but you are by no means restricted to this scale alone. To make the selection, you have to take into account several factors including:

• the size of the layout space available
• the amount of equipment available for your chosen prototype and era
• the amount of fine detail that you want to be able to see on your layout (do you want to see each individual rivet?)
• your desired scenery-to-track ratio
• layout portability
• your own physical accessibility

It's important to note here what is not included in these criteria. For one thing, I did not include layout operations in the equation. No matter what scale or gauge you choose, you can operate your layout with the vast majority of operating schemes that are common today; the model's size does not generally make a significant impact on its operating qualities or its appropriateness for use in operating sessions. What does matter is your own physical accessibility. If your eyesight does not allow you to read the reporting marks on smaller scale equipment, for example, then you may want to choose a larger scale. Other physical limitations such as height and mobility should be taken into account, but they are generally not significant factors in selecting a modeling scale. After factoring in all of the selection criteria, this is ultimately a personal decision. Some modelers choose a scale that lets them purchase equipment and run it out of the box with little or no modification; others may purposely choose an obscure scale or one that does not have a wide variety of commercially available equipment as a challenge to themselves. Whatever scale you choose, just remember that changing scales is not entirely unheard of. Many modelers start modeling with smaller scales and increase their scale size as they age for various reasons, and there are others that decrease their scale sizes as they age too (I used to know one modeler who switched from HO to N scale after he got into his 80s). If you're having a hard time deciding, purchase a couple kits and some equipment in the scales that you're considering and try them out. You'll find that as you work with the models, you'll naturally gravitate toward your own scale and gauge preference.