Excerpt from unknown newspaper.
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 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?
The first long distance roads in Europe (and
England) were built by Imperial Rome for
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 wagon
wheels and 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 question.
The United States standard railroad gauge
of 4 feet, 8.5 inches derives from the original
specification for an Imperial Roman war chariot.
Specifications and bureaucracies live forever.
So the next time you are handed a specification
and wonder what horses ass 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...
There's an interesting extension to the story
about railroad gauges and horses' behinds.
When we 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
might 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 had 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 is about as wide as two horses' behinds.