I received this interesting piece of trivia.  Next time you write a spec
think of the repercussions!

A useless fact (with a twist) about technology:

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?
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?
Roman war chariots first made the initial ruts, which everyone else had to
match for fear of destroying their wagon wheels and wagons. 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.

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.

And 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 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 Ass!


I bet you knew that all along.