The US standard railroad gauge (distance between the rails) is 4 feet,
8.5 inches, an exceedingly odd number?
Why was that gauge used? Because that's the way they built them in
England, and the English built the first US railroads.
Why did the English build them like that?
Because the first rail lines were built by the people who built the
pre-railroad tramways, and that is the gauge they used.
Why did they use that particular 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.
Okay! 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 the old, long distance roads in England, because that's the
spacing of the wheel ruts in the granite sets.
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 the ruts in
the roads? 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 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.