Horses Backside determines Space Shuttle Design

The US standard railway gauge – the distance between the rails – is four foot eight and a half inches.  To put it another way, 143.51 centimetres.  Either way, these are not very elegant numbers.  What could be the logical explanation?  Why is this gauge used?

Well, it’s because that’s the gauge used on British railways, and it was British expatriates who built US railways. So why did the British build them like this?  Because the first railway lines were built by the same people who constructed the pre-railway tramways, and this is the gauge they used.  So why was this gauge used for the tramways?  Because the tramway builders used the same jigs and tools that had been used for building horse-drawn wagons, which used the same wheel spacing.  Fine. So why did the wagon builders use this rather odd measurement?  Because, had they attempted any different measure, the wagon wheels would have broken on many of the old, long distanced roads in Britain.  Why?  Because that was the average spacing of the pre-established wheel ruts.  So how did those old rutted roads come into being?

Well, that’s because Imperial Rome built the first long-distance roads in Europe and Britain so their legions could keep all those uncivilised people in check.  The roads have been used ever since.  So what about the ruts in the roads?  Roman war chariots formed the original ruts.  It was decreed that all roads built in the Empire had to match these so that their wagon wheels and axles wouldn’t be destroyed.  Now, because the chariots were made either by Imperial Rome, or for Imperial Rome, and Imperial Rome’s bureaucracy set the standards, all chariots had the same wheel spacing.  The US standard railway gauge of four foot eight and half inches is derived from the original specification for an Imperial Roman war chariot.

Specification and bureaucracies tend to be self-perpetuating.

So next time you are handed a specification, or told to do a certain job in a particular way, and wonder what ass came up with it, you may be exactly right.

The Imperial Roman war chariots were constructed exactly wide enough to accommodate the rear ends of two war-horses.  But that’s not the end of it.  Have you ever taken a close look at the Space Shuttle sitting on the launch pad at Houston?  Attached to the sides of the main tank are two booster rockets.  These are known as Sold Booster Rockets, or SRBs.  Manufacturers of these SRBs have a factory based inUtah.  The engineers who designed them might well have preferred to make them a bit fatter but the SRBs had to be sent by train from Utahto the launch site in Florida.  The railway line between these two points has to run through a tunnel under the mountains, and the SRBs had to fit that tunnel.  The tunnel is slightly wider than the railway track, and the railway track is about the same width as two horses’ backsides.

So a major design feature of what is arguably the most advanced transport system in the world was determined over two thousand years ago by the width of a horse’s backside.


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