or How MilSpecs Live Forever
The US standard
railroad gauge (distance between the rails) is 4 ft 8 1/2 in
(1.44 m). That's an exceedingly odd number. Why is that gauge
used? Because that's the way they built them in England, and
the US railroads were built by English ex-patriots.
Why did the English build 'em 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 as they used for building wagons, which used
that wheel spacing.
OK! Why
did the wagons use that 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 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
breaking their wagons, were first made by Roman war chariots.
Since the chariots were made by or for Imperial Rome they were
all alike in the matter of wheel spacing (ruts again).
Thus
we have the answer to the original question. The United States
standard railroad gauge of 4 ft 8 1/2 in derives from the original
military specification (MilSpec) for an Imperial Roman army war
chariot. MisSpecs (and bureaucracies) live forever!
So, the next time you are handed a specification and wonder
what horse's ass came up with it, you may be exactly right. Because
the Imperial Roman chariots were made to be just wide enough
to accommodate the back-ends of two war horses.
A follow-up to this story: When Napoleon marched on Russia,
his army made much slower time than planned once they reached
eastern Europe because the ruts weren't to Roman gauge. Because
they made slower time than planned they got caught in the field
in the Russian winter rather than on the outskirts of Moscow.
And then, of course, they lost the war.
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 Thiokol at their factory at
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. 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' behinds.
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 ass.