The On-Line Magazine of Rideable Model Railroading

  NUMBER 134


© June 18, 2009   

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Riding Scales & Gauges

Written by Rick Henderson

When it comes to scales and gauges, the hobby of riding scale railroading may be difficult for newer people in the hobby to comprehend and perhaps even confusing for some of the more seasoned among us. For most of us in the hobby, our exposure to riding scale trains, which is any scale model of a train that you can actually ride, is limited to our home railroad or close-by railroads that are using the same track gauge. I recently wrote an article for the G-gauge community titled Scale, Scale & Gauge as G is One Gauge, Many Scales, Much Confusion. The Much Confusion really applies in the riding scales, where there are Multiple Gauges and Multiple Scales, frequently on the same railroad.

First, you should understand the basic terms. Scale in model railroading is defined as “the ratio between the size of something and a representation of it”, ie. A prototype locomotive and a scaled down model of it. Scale may be expressed as 1:8, 1/8 or 1-1/2” scale. Individually, ‘1:8’ means one unit in scale = eight units in full size, ‘1/8’ means one-eighth of the original size whereas ‘1-1/2” scale’ means 1-1/2 [1.5] inches on the model equals 12 inches on the real thing or the prototype being modeled.

Gauge on the other hand is defined as “the distance between the rails of a railroad track”. Gauge in railroad terms is divided into three categories, broad, standard and narrow. Standard gauge was established in England in the 1800's as 4' 8-1/2" between the inside head of the two rails. Standard gauge is the gauge of over 60% of the world's railroads today. Broad gauge is any gauge wider than 4'  8-1/2", whereas narrow gauge is any gauge less than 4' 8-1/2". In 1:8 scale, prototype standard gauge track is modeled at 7-1/4” or 7-1/2” track gauge.

Why is 4’  8-1/2” standard gauge? The gauge of 56-1/2” may seem odd but it actually started as an even 60” in 1830 during the construction of the Liverpool & Manchester railroad in England. The 60” gauge was being used at local mines at the time where mule powered tramway cars were used. The widespread myth that the gauge of railroad tracks came about from the ruts caused by Roman chariots was more likely started by some bored mule driver at the mines than any facts. The gauge was first measured to the outside of the rail heads, which at the time were 2” wide, making the inside gauge 56”. During construction, it was discovered that an extra 1/2” was needed between the wheel flanges and rail heads to allow for better operation on curves so the track width was widened by 1/2”. Since the width of the rail head could vary, it was more practical to measure track width on the inside of the rail heads, which is how 56-1/2” or 4’  8-1/2” became the standard railroad track gauge.

If you have done model railroading in the table top scales of HO & O or other small scales, your exposure to the hobby was in one of those scales. “O” scale is 1:48 scale and “HO” scale is 1:87 scale. [HO stands for Half-O]. Everything is the same relative size within a scale. All O-scale trains, structures and figures are all 1/48th the size of the prototype. If you did narrow gauge modeling in O-scale, only the track gauge changed to a smaller width while the scale or size of the model stayed the same. All model train gauges, like the prototype, measure track gauge to the inside of the rail heads; with one exception from the early days. In the early days of O-gauge toy trains, when the tracks for ‘toy trains’ were round, gauge was measured to the top center of the round rail until prototypical looking rail was introduced.

If you have done G-gauge railroading to any degree, you found that G-track is 45mm and there are several different scales of trains modeled that use the same track gauge. That same principle applies to the riding scale hobby where we have multiple scales of trains at most railroad tracks running on one track gauge. Regrettably, in 1:8 scale, that track gauge varies in the U.S., while the rest of the world is fairly standardized.

Fortunately, in our riding scales hobby, railroads do not require members or guests to run only one scale of train on their track. They may require safety chains, equipment inspections, orientations and waivers, but what scale you run is up to you.

7-1/4” vs. 7-1/2” Gauge

Why there are two different track gauges for 1:8 scale railroads is a good question. The gauge of 7-1/4” was adopted in England in the early 1900’s as the standard, with the first commercially built 7-1/4” gauge trains being built in 1908 by Bassett Lowke, founder of Miniature Railways (Great Britain) Ltd. At the time, most interest was focused on modeling in 10-1/4” to 15” gauges for estates and amusement grounds. This new 7-1/4” gauge was to model standard gauge track in 1-1/2” scale. If you do some quick math, you find that 56.5” divided by 8 equals 7.06”, not 7.25”. So 7-1/16th inches should be the actual gauge for 1:8 scale. The idea of modeling to 1/16th inch precision in 1908 may have been impractical if you were going to mass-produce. If they wanted an easy to measure dimension, why 7-1/4” and not an even 7” is not clear.

The 1/4” Demarcation Line In the U.S. and Canada, you will find both 7-1/4” gauge railroads and 7-1/2” gauge railroads. The overlapping division line between the two gauges is in Ontario and Quebec Canada and the northeast U.S. starting in New Jersey and parts of Pennsylvania and all areas to the northeast, with these areas primarily using 7-1/4” gauge for 1:8 scale. Most 1:8 scale railroads west and south of Pennsylvania use 7-1/2” gauge for 1:8 scale.

So, if 7-1/4” is the common gauge in all other countries, why is 7-1/2” used in most of the U.S. and western Canada? It may have been a simple lack of communications in an emerging post –war hobby. Riding scale railroading was well established in England by the early to mid 1900’s, when the hobby started up in the northeast United Stated and eastern Canada. The only widely available reference material was Model Engineering magazine, which was published in England and referenced 7-1/4” gauge as the proper gauge. Such a publication in the 1930’s, which was also during the U.S. Great Depression, likely, saw little circulation outside of New England. By the 1940’s the war was upon us and hobby railroads went to the back burner.

In the 1940’s, after the war, a company called Little Engines in southern California was the only company widely producing a catalog of their riding scale model trains and they included the standards they were building to; those being 7-1/2” gauge as the standard for 1:8 scale, despite knowing that 7-1/4” was used elsewhere and even mentioning that gauges could be set to 7-1/4” on their trains. Their choice of 7-1/2” gauge has been cited as coming from a group or railroaders in the Chicago and Michigan area that had established standards on an existing railroad. Since Little Engines built in 7-1/2” gauge, that is what modelers accepted as the correct standard and built their railroads accordingly. The hobby grew well in California and then across the U.S. with Little Engines being the leading manufacturer of locomotives and parts. They communicated through their catalog and people took that as the source of information, simply because there was no other well known source for standards in the U.S.

In the riding scale hobby, the best idea is for a new modeler is to first check what gauge of track is locally available to run on and they usually obtain equipment they may easily run there; their other option being to build their own track at home. While the two most popular gauges in the U.S. are 7-1/4” and 7-1/2” gauge, there are less common smaller and wider gauges around to also consider.

1.5 & 1.6

To overcome the shortcoming of the minor scale discrepancy created by building 1-1/2” or 1.5 scale trains to run on 7-1/2” gauge track, some more scale conscious have switched to building in 1.6 scale for 7-1/2” gauge track rather than the traditional 1.5. This is actually the easier way to make the trains correct for 7-1/2” track. However, for most modelers the difference between 1.6 & 1.5 will not be noticeable and both will work well for them. Even train items built in these different scales will work well with each other coupled together in the same train.

What about I.B.L.S.? As worldwide communications improved and it became evident that having two standards for 1:8 scale modeling in the U.S. was counterproductive, an attempt was put forth to adopt a true standard for track gauge, wheel profiles and couplers. The organization known as the International Brotherhood of Live Steamers was formed, with representatives from areas around the world working with riding scale railroads. Via mailings, all known private and club railroads were contacted and asking for input on what the standards should be so a single set could be established. From the replies, it became abundantly apparent there was no easy solution within the U.S. and the I.B.L.S. settled on adopting and recommending standards following those being used in California and sent these out as “proposed standards” to everyone. Since these first included 7-1/2” as the correct gauge for 1:8 scale, they were never officially adopted by everyone and have remained as proposed ever since. However, in the U.S., these proposed standards have been used by most everyone for wheels and couplers and each area has used their local gauge standard. This has allowed for the trains to easily travel to other railroads and interchange equipment fairly easy, except for crossing The 1/4” Demarcation Line in the northeast. Today if you look at most IBLS wheel and coupler charts, you will find gauging standards for both 7-1/4” and 7-1/2” that have become the accepted standards by most.   

most popular gauges

Will we ever have one gauge in the U.S.? That is very doubtful because there is simply too much invested by too many people worldwide. If there were ever to be a change, it would likely need to be to standardize on 7-1/4” and since most of the U.S. is already 7-1/2”, it simply will not happen. Rudyard Kipling best expressed it as "Oh, East is East, and West is West, and never the twain shall meet."

In the end, the hobby is more about enjoying the ability to ride a train than the -1/4” that defines where that train may run. We have come to accept that both gauges are close enough to scale for all to enjoy the ride. For now, when you are looking to purchase, confirm the equipment wheel gauge first and then just enjoy the hobby with the rest of us.

Written by Rick Henderson


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