In Case You Ever Wondered.....

If you've ever seen the space shuttle on the old launch pad, maybe you've noticed that there are two big booster rockets attached to the sides of the main fuel tank.

These are solid rocket boosters (SRBs). The SRBs are made by Thiokol at their factory in Utah. The scuttlebutt around the water fountain is that 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 the tunnel. The tunnel is slightly wider than the railroad track.

Now, the U.S. standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That struck me as a really odd number. I couldn't help wondering why that particular gauge was used.

As it turns out, that's the way they build them in England and the U.S. railroads were built by English expatriates. But then, why did the English build them like that?

It's because the first rail lines were built by the same good folks who built the pre-railroad trams and that's the gauge they used. OK. Then why did the pre-railroad tram use that gauge?

It's because the people who built the tramways used the same jigs and tools that they used for building wagons, which just happened to have that particular wheel spacing.

Fair enough.

But why did the wagons have that particular wheel spacing?

Because if they tried to use any other spacing, the wagon wheels would break in the deep wheel-ruts on some of the old, long-distance roads in England.

Why in the world did the wheel-ruts have that odd spacing?

Because those first long-distance roads were built by Imperial Rome for its legions and have been used ever since. The initial ruts in the roads --which everyone else had to match for fear of destroying their wagon wheels -- were first formed by Roman war chariots. Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing.

And these Imperial Roman war chariots were made just wide enough to accommodate the back ends of a pair of fine Iberian war horses.

So the solid rocket boosters are the size they are because Roman war chariots were the size they were.

The point of this tale is simple: very often things are done the way they are done, not because it's optimal, but because of the influence of some horse's ass.

sj