The rear end of a horse, Solid rocket boosters and trains

[Knothead]

Does the statement, "We've always done it like that" ring any bells?  .
.
. .   Interesting!

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 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 feet, 8.5 inches is
derived from the original specifications for an Imperial Roman war chariot. 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 army
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 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 mountns . .
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.

- And - You thought being a HORSE'S ASS wasn't important!

[nscnotp1]