An amusing story I came across
We've Always Done It That Way!
Does the statement, "We've always done it that way" ring any bells? The
US standard railroad gauge (distance between the rails) is 4 feet, 8.5
That is an exceedingly odd number. Why was that gauge used? Because
that's the way they built them in England, and English expatriates built
the US Railroads.
Why did the English 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 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 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 imperial
Rome, they were all alike in the matter of wheel spacing.
The United States standard railroad gauge of 4'-8.5" is derived from the
original specifications for an Imperial Rome war chariot. And
Bureaucracies live forever.
So the next time you are handed a specification and wonder what horse's
arse came up with it, you may be exactly right, because the Imperial
Roman war chariots were made just wide enough to accommodate the back
ends of two war horses.
Now the 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 Thikol at their factory in Utah. The engineers who
designed SRBs would have preferred to make them a bit fatter to carry a
bigger fuel payload, 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, as you now know, is about as wide as two horses's
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 a horse's arse.
And you thought being a horse's arse wasn't important!