3297: OH Scale
| OH Scale |
 Title text: To access distant parts of the project, I ended up building a regular-scale passenger train inside each rail. |
Explanation[edit]
This comic references the HO (or H0) scale of 1:87, commonly used for model train sets. Due to a typo, the ratio values were switched, becoming 87:1. This means the trains, tracks and all other pieces are 87 times the size they would be in real life, resulting in 'model' that is an improbably large 7,569 (87 x 87) times the size it should have been. To reflect this, or perhaps as part of a similar error, it has been nominally called "OH Scale", inverting the letters of the standard scale name. "Oh" is also a usual spelling for a common spontaneous expression of surprise, such as might be emitted by someone seeing such a scale model for the first time.
Creating a model at 87 times the real-life dimensions means that you are dealing with tracks twice the height of a house and trains the height of skyscrapers. A 'model' train set of this size wouldn't fit in a typical yard and would need planning permission in most jurisdictions. This contrasts with the HO scale trains the protagonist intended to build, which likely would have easily fit in one of the rooms in their house.
| Object | Real world | HO scale | OH scale |
|---|---|---|---|
| Wheel diameter | 1.016 m (40 in) | 11.7 mm (0.46 in) | 88 m (290 feet) |
| Rail height (132 pound main line rail) (from trains.com) | 18.0975 cm (7.125 inch) | 2.08 mm (.083 inch) | 15.74 m (51.7 feet) |
| Rail gauge | 1.436 m (4 ft 8.5 in) | 16.5 mm (0.65 in) | 125 m (410 feet) |
| Typical locomotive (e.g. the EMD F7A) | 15.44 m long, 3.23 m wide, 4.57 m high (50 ft 8 in long, 10 ft 7 in wide, 15 ft high) |
177.5 mm long, 37.1 mm wide, 52.6 mm high (7 in long, 1½ in wide, 2 in high) |
1.343 km long, 281 m wide, 400 m high (0.83 miles long, 920 feet wide, 1300 feet high) |
HO scale is 'half of O' scale. O scale (originally 'zero' scale) tends towards a 1:48 scale, depending upon the vendor, where 1/4 inch on the model equals 1 foot in real life. HO scale models are therefore around half the size of O scale models.
The title text expands the joke further, saying that, due to the size of the model, he had to build a regular-sized train within it to get to far portions of the project.
Model rail and its size constraints have been covered previously in 878: Model Rail.
"OH Scale" could be a word play on Big O notation, which is a mathematical shorthand that describes orders of magnitude, and has been featured previously in 399: Travelling Salesman Problem and 2939: Complexity Analysis.
Transcript[edit]
- [A two-story house is sitting in a a plain surrounded by several assorted trees, the highest of which rise to double its height. To the right of the house, taking up most of the panel, is a large metal bar (a rail), resting on two giant railroad ties (seen end-on) to which it is anchored with track clips; the bar is about eight stories tall, and the clips are comparable in size to the house. A scaffolding tower leads to the top of the bar. Atop the bar is a huge, incomplete wheel, with the left half and the bottom quarter of the right completed. The wheel is approximately fourteen stories tall and has scaffolding going up both its sides (presumably to hold it in place) and up the incomplete portion.]
- [Caption below the panel]: Due to a typo in the plans, I've been building a 87:1 model train set in my yard.
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Discussion[edit]
Title should be "Oh MY" Scale! BorQhue del Sol (talk) 16:45, 11 September 2026 (UTC)
Now I know what happened in Saudi Arabia when they planned The Line 195.49.224.20 16:59, 11 September 2026 (UTC)
[looks up] [looks higher] [looks even higher] You can't park there, mate. 2A01:CB08:82C3:1A00:1539:E329:830E:D7E8 20:51, 11 September 2026 (UTC)
What is the actual object being built here? Some circle on top of a rectangle…? Fabian42 (talk) 21:40, 11 September 2026 (UTC)
- Looks to me like a 'model' railway wheel (construction hasn't yet reached the rest of the train, yet!) atop a 'model' rail seen from the side, in turn supported by sleepers(/ties) at the ground level. But you could perhaps measure the depicted heights, 78 times real life and 6084 times model-sized, and try comparing the adjusted pixels against the buildings. I reckon Randall's probably done a decent job of being accurate, in that regard, against the house features (say its under-stoop 'foundations'), which might be roughly locomotive wheel in size, depending upon the type of engine being modeled. 78.151.45.228 22:31, 11 September 2026 (UTC)
If Cueball is building a scale model of Randall's hometown then the area he would need would be 48441.6 square miles meaning that in order to build it Cueball would have to steal the state of Mississippi--THOASTER (talk) 02:17, 12 September 2026 (UTC)
'O' scale, in the UK is to 1/43.5, which you will note is twice H0. Europe often uses 1/45, just to be more metric. 2A00:23C8:2547:A201:5D14:2732:36E7:BC19
- When making my own edits, I retained the 1:48 someone else mentioned and went for saying that was roughly half of 0-scale, knowing that it practically varies according to the particular manufacturer that initially adopted "half"-scale in any given market doing it slightly differently (to suit their particular practicalities, like adopting a given narrow-gauge track from one scale as a given full-gauge track at another, etc). Exact details for each H0-implementation is documented better in the obvious place, I didn't want to try and go into that in the Explanation, but it is of course an interesting note that 1:78's 'non-half' counterpart jumps around in the vicinity of being 2:87 or 1:87/2. 78.151.45.228 19:00, 12 September 2026 (UTC)
I measure the two story house as 18 pixels. I measure the rail as 113 pixels. If we assume the house is 8 feet per story, this places the rail as about 100 feet tall. This would in turn make the scale more like 170:1. --Divad27182 (talk) 15:03, 12 September 2026 (UTC)
- But did you allow for perspective and foreshortening?96.61.125.76 16:38, 14 September 2026 (UTC)
Rail height HO scale should be 0.208 cm (or 2.08 mm) 82.116.241.74 16:23, 12 September 2026 (UTC)
Building a "regular-scale passenger train inside each rail" as described by the title text is not possible. While the height of the rail would be more than sufficient to do this, the width of rail definitely is not enough. When you see the cross section of a regular rail like in Wikipedia article Rail profile and of a model of an HO-scale train next to each other, you can easily see this. The rail head makes the rail look thick an massive, but it has not enough height to enclose an H0-train. The rail web below it is actually far too thin to enclose the width of an H0-scale train. And the rail foot has not enough height to enclose an H0-scale train. A smaller narrow-gauge train with a very low height might fit into the rail, but not a typical passenger train. Or you would need to use some quite extraordinary rail profiles. Enclosing the regular train with the 78:1 scale rail won't be possible, for the same reason. The ratio between a regular rail and the 78:1 scale rail is the same as the ratio between a H0-scale train and and a regular train. Therefore, it has the same problem. Adding an illustration with a cross section of a real rail and a cross section of an H0-train with the same scaling could be helpful. --2A02:8070:2481:E440:F8D1:1065:E5B7:73C5 16:27, 13 September 2026 (UTC)
- Adding the width and height of the rail head, the width and height of the rail web, and the width and height of the rail foot of a typical modern rail to the table would also help to explain, that the train would not fit inside the rail. --2A02:8070:2481:E440:F8D1:1065:E5B7:73C5 16:32, 13 September 2026 (UTC)
- You'd find Loading gauge#Standard loading gauges for standard track gauge lines and Structure gauge as further useful resources, if trying to superimpose a 78x difference of rail profile against what might (or might not) fit inside it. 78.151.45.228 17:47, 13 September 2026 (UTC)
All the naysayers above...I believe Randall 2001:1C00:1816:9800:0:0:0:1002 21:26, 13 September 2026 (UTC)
What material and construction method could Randall possibly be using to end up with such a jagged edge on the wheel construction? It doesn't seem to match poles, beams, bars, or panels. These Are Not The Comments You Are Looking For (talk) 06:09, 14 September 2026 (UTC)
- LEGO blocks, perhaps? RAGBRAIvet (talk) 16:43, 14 September 2026 (UTC)
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