Goverment Decisions, and How Specs Live Forever The US Standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That's an exceedingly odd number. Why was that gauge used? Because that's the way they built them in England, and the US railroads were built by English expatriates. Why did the English people build them like that? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that's the gauge 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 that wheel spacing. Okay! Why did the wagons use that odd wheel spacing? Well, if they tried to use any other spacing the wagons would break on some of the old, long distance roads, because that's the spacing of the old wheel ruts. So who built these old rutted roads? The first long distance roads in Europe were built by Imperial Rome for the benefit of their legions. The roads have been used ever since. And the ruts? The initial ruts, which everyone else had to match for fear of destroying their wagons, were first made by Roman war chariots. Since the chariots were made for or by Imperial Rome they were all alike in the matter of wheel spacing. Thus, we have the answer to the original questions. The United States standard railroad gauge of 4 feet, 8.5 inches is derived from the specification for an Imperial Roman war chariot. Specifications and bureaucracies live forever. The Imperial Roman war chariots were made just wide enough to accommodate the back ends of two war-horses. Now let's cut to the present... The Space Shuttle, sitting on its launch pad, has two booster rockets attached to the sides of the main fuel tank. These are solid rocket boosters, or SRBs. A company builds SRBs at its factory in Utah. The engineers who designed the SRBs wanted 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 has to run through a tunnel in the mountains. The SRBs had to fit through that tunnel, which 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 two thousand years ago by a horse's ass. Which is pretty much how most government decisions are made. The next time you are handed a specification and wonder what horse's ass came up with it, you may be exactly right.