The Infrastructure of Today Defines Tomorrow

STANDARDS – RAILROADS to the Space Shuttle

Was The Standard Railroad Gauge Determined by Roman Chariot Ruts?

Probably not, however, read the following.

Ever wonder where those engineering specifications come from?

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 mountains. 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!

A follow up to this story:

Above is the often cited myth authored by unknown, but it seems to be posted all over the web. Taking it a step further, one could argue that the "meta-cause" of the Shuttle Challenger disaster was the indirect result of incremental thinking in design and was set in motion over two thousand years ago by the width of a horse's behind.

The actual history of railroad gauges is more interesting and seems to parallel present day standardization issues well.

Denny S. Anspach suggest that if the Roman ruts matched the English wagon ways and early railroads, it was not that George Stephenson (builder of the first public railway) copied the Roman road ruts, people simply responded to the same natural need: the size of the most efficient and stable vehicle that could be pulled by one horse. Matt Wall also debunks this tale referring to engineering needs of the day. The standard gauge was the widest original width you could reliably make an iron axle (pre-bessemerized steel days) that would support the then-weight of locomotives.

However the standards story isn't too far off for once a critical mass is reached, any advances in technology could not change the standard. Economies of scale and standardization helped mass production, and interoperability enabled an actual network as opposed to a conglomeration of vaguely interconnected subsystems. This de-facto standardization created the lock-in.

There is more history on this urban legend in other places. But the interesting part is how it relates to competition and how critical mass is used to the incumbents' advantage.

The economics of networks also applies to standardization on the web. It would seem from the NYT's interview with economist John Steele Gordon titled "To Gauge the Internet, Listen to the Steam Engine", that he would only agree. Check How Microsoft is Building a Global Monopoly, by Nathan Newman, and Making Microsoft Safe for Capitalism by James Gleick.

More follow up to this story:

From: claude@espresso.rt.cs.boeing.com (Claude Ginsburg)
Subject: Rail Gauge (continued)
 
.....when Napoleon marched on Russia, his army made much slower time than planned once they reached eastern Europe. Because the ruts weren't to Roman gauge, keeping him from reaching Moscow before winter set in and froze his army.. Because they made slower time than planned ... they got caught in the field in the Russian winter rather than on the outskirts of Moscow. And then, of course, they lost the war.
 
 

Another footnote to the article:

When Napolean invaded Russia the difference in wagon ruts slowed him down keeping him from reaching Moscow before winter set in and froze his army. When Germany invaded during WWII the difference in railroad gauge slowed down the German logistics. They had planned on the difference in rail size and had sets of wheels for the wider Russian gauge but the fact that the Russian engines were wider meant that they carried more fuel and water. This meant that the depots were spaced far enough apart that the German engines couldn't make it from one depot to the next with a full load of cars without running out of fuel or water part way.  

Also see:

http://www.snopes.com/history/american/gauge.asp

http://www.discoverlivesteam.com/magazine/34/34.html

http://www.sisostds.org/webletter/siso/iss_39/art_163.htm

http://query.nytimes.com/gst/fullpage.html?res=9E06E2D61331F935A1575BC0A9679C8B63