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Posted by Peter Falkenberg Brown
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This was emailed to us .... forwarded via the "engineer circuit"...
We're not sure who the original author is ...
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 which horse's rear 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.
So, the major design
feature of what is arguably the world's most advanced
transportation system was determined by the width of a Horse's Rump!
