The US standard railroad gauge?

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E. McKeesport & Allegheny

Michael "Mikey" Moore
The US standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That is an exceedingly odd number.

Why was that gauge used?
Because that is the way they built them in England, and English expatriates built the US railroads. !

Why did the English build them like that? !
Because the same people who built the pre-railroad tramways, and that is the gauge built the first rail lines they used.

Why did they use that gauge then?
Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used the same wheel spacing.

Why did the wagons have that particular odd wheel spacing?
Well, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance roads in England, because that's the spacing of the wheel ruts.

So who built those old rutted roads?
Imperial Rome built the first long distance roads in Europe (and England) for their legions. The roads have been used ever since.

And what determined how wide apart the ruts in the roads would be?
Roman War chariots formed the initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for (or by) Imperial Rome, they all had the same wheel spacing. The United States standard railroad gauge of 4 feet, 8.5 inches is derived from the original specification for an Imperial Roman war chariot. This is because the Imperial Roman war chariots were made just wide enough to accommodate the back ends of two war-horses.

Here is an interesting twist to the story about railroad gauges and horses behinds!
When we see a Space Shuttle sitting on its launch pad, there are two big booster rockets attached to the sides of the main tank. These are solid rocket boosters, or SRBs. Thiokol makes the SRBs at their factory at Utah. The engineers who designed the SRBs might have preferred to make them a bit fatter, but the SRBs had to be shipped by train from the factory to the launch site. The railroad line from the factory happens to run through a tunnel in the mountains. The SRBs had to fit through that tunnel. The tunnel is slightly wider than the railroad track, and the railroad track is about as wide as two horses' behinds. So, a major design feature of what is arguably the world's most advanced transportation system was determined over two thousand years ago by the width of two horse's rear ends.
 
Mikey, this story has a lot of intuitive "Makes sense!" about it. In this case, though, it is largely bogus...or the general conclusion doesn't necessarily follow. Still, it was the idea that counts for me, and I thank you for wanting to share it with us. :) It is really what this forum is all about.

-Crandell
 




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