Many of the layout design conventions we take for granted were developed in HO scale. As the most popular modeling scale, HO receives the bulk of press coverage and therefore, these design conventions are well entrenched in our thinking.

For HO and N scales, the conventions serve well for the typical spaces modelers have available. However, the design train comes off the rails when the modeling scale increases to 1:48 or even 1:64. An HO modeler moving into these scales is in for culture shock on many levels and since I’m most familiar with quarter-inch, let’s look at what happens.

The first rude awakening is encountered when one reaches a room corner. In HO, a 36-inch curve is nice while a 48-inch radius is quite generous; long equipment like Hy-Cubes, eighty-foot passenger cars and such look pretty good on such curves. However, 48-inches is a train set radius in quarter-inch scale, being the rough equivalent to 26-27-inch curves in HO, and we all know how grotesque the visual compromise is on curves that tight.

For the standard gauge mainline equipment most modelers typically want to run, your need a 60-inch or greater radius in this scale. Things start to look nice on 72-inch curves and look even better in the 80-90-inch plus range. This applies to both turning the room corners and any peninsula turn back loops. Let’s add some more blooms to this rosy picture and discuss turnouts.

Observation and experience has taught me that a No.10 frog is the minimum size for a mainline turnout and a No. 12 will be even better. A No. 10 crossover will stretch out around four-feet from switchpoint to switchpoint and the same distance is required to reach the clearance point for an adjacent track with a single turnout. I know, you’re screaming who has space for turnouts that long? Believe me, you can find the space if you really want to.

What’s wrong with a No. 8 or the HO default standard No. 6? Even though the actual lead is proportional in quarter-inch scale, the diverging route has to travel farther because of the wider track gauge, making them look too sharp, at least to my eyes.

These are just two of the factors that explain why most O scale layouts default to a roundy-round loop of the room that resembles the Indianapolis Motor Speedway and I think you begin to see the problems you’ll encounter with conventional linear layout design practices. The amount of space required to turn room corners and make a 180-degree loop at the end of any peninsula justifies the you-need-an-aircraft hanger stereotype that quarter-inch scale has among the uninitiated. We haven’t even discussed how long a 20-30-car train will be or the amount of run needed to get one track over another one. Thoroughly conditioned by the HO mind set and expectations of how much layout one supposedly must have in a given space, people always want to blame the scale for being too big rather than look at how unrealistic their own expectations are.

Each modeling scale has its own strengths and weaknesses. The strength of N scale is in portraying a panoramic scene. Its weakness is that individual details are all but irrelevant. For quarter-inch scale it’s the polar opposite, because the viewpoint is more close-up and intimate and individual details play a more important role.

I’ve worked in quarter-inch scale for ten years now and it took me three, if not five of those years, to rid myself of the HO scale mentality I brought with me. The initial design of the I&W reflected that mentality with its track dense nature that left little if any room for scenery. I finally understood that the problem wasn’t the larger scale or the perceived lack of space. It was the feeling of being deprived that was generated by constantly comparing the new scale to what I was accustomed to with the old one.


Gee, I can’t fit as much track in here now.
Wow, that runaround looks awfully short.
Boy those turnouts eat up a lot of room.
Did I measure that curve radius correctly?
Why does everything look so overcrowded?


This constant comparison between what I had and what I used to have was deadly to my satisfaction, until I understood what the real problem was. The same problem that plagues modelers regardless of the scale, theme, era or whatever: we all try to stuff too much into the space we have because we’re afraid of feeling deprived. So we cram in feature upon feature and then wonder why it looks like crap and we’re not happy campers anymore.

The key to working with quarter-inch scale is to understand what truly matters to you. If you want long trains and open running be prepared to pay for space, lots and lots of space. Be prepared to swallow a compromised track gauge and many more compromises because that’s what it takes in this scale if you just want to open boxes, put stuff on the track, then set it and forget it.

Of course, the other option is to learn how to focus on what’s actually important to you because by virtue of its size, quarter-inch scale excels at teaching you how to focus and set realistic expectations.

Can you have a satisfying quarter-inch scale layout in a limited space? Yes, you absolutely can, if you learn, understand and respect the scale for what it offers and don’t expect it to be HO on steroids. If you can make that mental shift, you’ll find working in this scale a real blast.



  1. Ctown

    As always interesting commentary on various aspects of modeling. I too have struggled with a similar issue, but in a much larger scale (1/29). At three times the size of HO, a single 40′ boxcar is a little under 2′. A 90′ flat would be over 3′! One would initially think that a ‘outdoor railroad’ wouldn’t have the same size constraints as an indoor railroad, but it does. You’re available modeling space is only so big. What a 18″ curve in HO looks and feels like is a 4′ diameter curve in large scale. Even a 12-20′ curve still looks sharp to my eyes (I have a buddy in AZ that is building 100′ radius curves that actually look right!). What I have discovered and learned is that it’s “okay” to break the mold.

    I wanted a #9 turnout for my layout instead of #4’s and #6’s so I went ahead and built one. Now when I put a GP9 on the turnout it looks right to my eye. Nothing is compromised in terms of tightening up or downsizing for the sake of jamming more layout into less space. The compromise that I’ve come up with is that if I want to correctly model this one scene, I have to reserve a space of 7-10′ by 50-60′ dedicated for that one scene. That includes building a feed mil that stands 4′ tall, and 7′ wide. Anything less and it looks toylike. Selective compression doesn’t work when everything is so compressed to a point of meaningless.

    Does that mean I can’t jam a 4′ diameter loop on each end? Sure, I could if I wanted too, but I don’t! Instead the scene will consist of 3 #9 turnouts, a main, siding, and spur. At this point the planed structures are two; a feed mill (a scale 160’x 150′) and a depot (70’x30′). That’s it. Nothing more nothing less.


  2. mike

    Craig I can only imagine what you have to deal with in a scale that big. I suspect it makes any indoor modeling scale look tiny. It sounds really neat.