|
Credit Valley Ramblings Online
Scale versus Gauge
One of the hardest concepts for new model railroaders to understand is the difference between the terms scale and gauge. The definitions of these two terms are very simple but how they are used or misused can be very confusing.
Scale is the relationship between the model and the item it is based on. For example in HO scale, usually expressed as a ratio 1:87 or as a fraction 1/87, one centimetre of the model is equated to 87 centimetres of the real item.
Gauge is the actual distance between the inside edge of the rails. What can be confusing is that this measurement can be equated to different widths of track depending on the scale you are modelling.
Most railways as we commonly see them at railway crossings are built to "Standard Gauge". This is a distance of “four feet eight and a half inches" or 56 1/2". This unusual width was officially accepted as the standard measurement for railway track in The Railway Act of 1875 in Canada and by a similar enactment in the United States. Prior to this time railways could not interchange their cars with the next railway as it was often a different gauge of track. Military troop movements and shipping during the Us Civil War showed the need for a standardisation between railways and the creation of large railway networks.
Why 56 ˝ inches. This dates back to Roman Times when roads were built with ruts spaced at this width. That is what was required for chariot hauled by two horses. Design engineers do not like to give up on practices that work, even when they have no idea how old that practice gets.
Narrow gauge, Broad gauge, Standard gauge?
What does this mean?
Not all real railroads were built to “Standard Gauge”. In the past some railroads were built to other widths or gauges. Some early British railways were originally constructed to gauges of five foot six inch (66") or even seven foot six inch (90") While more stable they cost more to build and maintain than the smaller “Standard Gauge” railways. These became known as "Broad Gauge Railways". Some were even built in Canada and later re-gauged or narrowed to Standard Gauge.
To minimise construction cost many industrialists found that building their private railways to a smaller gauge or "Narrow Gauge" was less expensive than building a ‘standard’ railway. As these railways did not connect with other railways they did not have to interchange with major railways. Examples of this style of railroads are logging railways, carrying logs from the bush to the mill; or
mining railways carrying ore to crushing plants.
Secondary railroads into mountainous country were also built to "Narrow Gauge" because the smaller locomotives and rolling stock was lighter and could be hauled up steeper grades and around tighter curves than their larger cousins. This was an asset when building in narrow valleys between towering mountains.
How does all this relate to model railroading? In magazines and books relating to this hobby you will see references to On30, HOn3, Gn15 etc. What this means is the Scale ( G - 1:22.5, O-1:48, HO-1:87, or N -1:160) followed by the letter n to designate that it is a narrow gauge model, and followed by a number indicating the width of the gauge. ( 3 = 3 feet between the rails, 30 = 30 inches, 15 = 15 inches, etc.)
Trackage built to represent HO scale Standard Gauge can be used to represent O scale 30 inch gauge, or G scale 15 inch gauge. Similar relationships exist for N scale Standard Gauge trackage.
If you are still confused and wish to know more (not every one is interested in this knowledge) come and see us at The Credit Valley Railway Company Ltd. We have 'experts' who can help you understand, and books to help you understand.
|
