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Where Did Our Modern Measurements Come From?

Some fun history!  A lot of my personal projects include railway EPC projects and I remember early on in my career wondering how people originally came up with the measurements on a railroad gauge.  It seemed kind of odd to be being that the distance between the rails is usually 4 feet 8.5 inches.  Who on Earth came up with this number and why is it so specific?

Many of today’s projects are based on this gauge and measurement. Where did we get this number?  Who created it?  And why was that gauge used?

For one, this is the way they were built in England, and English expatriates designed the U.S. railroads.

Why did the English build use these measurements? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that was the gauge measurement they used.

Why did ‘they’ use that gauge? Because the people who built the tramways used the same tools that they had used for building wagons.  And surprisingly, wagons used that wheel spacing measurement.

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 this was the spacing of the wheel ruts in the roads.

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

History reveals that the ruts in the roads were created by Roman war chariots.  Everyone else decided to match these ruts out of fear of destroying their wagon wheels!

Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing. Therefore the United States standard railroad gauge of 4 feet, 8.5 inches is derived from the original specifications for an Imperial Roman war chariot.

If you think about it, it is kind of like that old tale of a woman at Thanksgiving dinner cutting the sides off the holiday meat.  One day her husband finally asked her, “Why do you cut the ends off the meat?”  To which his wife replied, “I don’t know, my mother always did it.”

So he found his mother-in-law and asked her why she cut the ends off of the holiday meat, to which she replied, “I don’t know, my mother always did it.”  He finally found his wife’s grandmother and asked her why she cut the sides off of the holiday meat, to which she replied, “Oh I always did that because my oven wasn’t big enough to cook the whole ham!”

While this is a funny story (that I am sure many of us can relate to), this is what has happened with the modern measurements many of us use in EPC works today!

So the next time you are handed a specification or procedure and wonder, “Who came up with these measurements?” you may be shocked with the answer. Imperial Roman army chariots were made just wide enough to accommodate the rear ends of two war horses. That’s right… our today’s modern measurements were based on the average width of two horses asses!


And if that isn’t enough, now here’s a twist to the story:

When you see a Space Shuttle sitting on its launch pad, there are two big booster rockets attached to the sides of the main fuel tank. These are solid rocket boosters, or SRBs. The SRBs are made by Thiokol at their factory in Utah. The Engineers who designed the SRBs would 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, and the SRBs had to fit through that tunnel. The tunnel is slightly wider than the railroad track, and the railroad track, as you now know, is about as wide as Imperial Roman army chariots.

So, a major Space Shuttle design feature of what is arguably the world’s most advanced transportation system was determined over two thousand years ago by the width of Imperial Roman army chariots, which were based on the size of two horses standing next to each other. What else in today’s modern world is controlled by Imperial Roman army chariots?



Peter Wyss