A Dangerous Phrase — Sometimes

Today’s topic is something I have researched for several years (actually, I started yesterday, but, I plan to continue my research for many years — several years). There is an interesting theory about the wheel spacing of a Roman chariot and its impact on today’s railroad rail spacing (TRRRS).

The spacing of today’s railroad rails is 4 feet, 8.5 inches. This seems like a random dimension, right? But think about it, what else pops in your head when you hear 4 feet, 8.5 inches? Write the (obvious) answer here: ___________________.

The story goes something like this: That particular spacing was adopted because that’s what was used in England. But why did the English use that spacing? Well, because the people who built the English railroads used the same spacing as the people who built the English tramways who in turn, reused the tools and jigs from building horse-drawn wagons.

But why did wagons have that particular wheel spacing? Because that was the spacing of the wheel ruts. And these wheel ruts were the result of Roman chariots. And if you were a smart waggoneer, you would construct your wheel spacing to match these existing ruts and avoid risk of wheel damage.

And finally, what was the reason for that particular wheel spacing on chariots? What did you write down in the blank line above? Yep, 4 feet, 8.5 inches is the exact width necessary to accommodate the back end of two horses.

And that’s not all, an interesting reverse-extension of this story is that because this dimension impacts cargo width of all things transported by rail, the design of the space shuttle’s booster rockets was therefore affected. The boosters, built in Utah, were transported (by rail) to the launch site. Think about it — the design of the space shuttle’s booster rockets was perhaps impacted by the width of the back end of two horses.

So, is this true or coincidental? I tried to obtain confirmation by contacting the National Historical Society and asked to speak to Diomedes (one of the few chariot driver names I could recall from the stories my uncle would tell me). The curator claimed Diomedes was “unavailable” and even went so far as to say he was likely “no longer with us.” I received the same answer when I asked for Antilochus. I chuckled to myself, having used the same excuse when receiving calls from people I borrow money from. In any case, let’s agree there is some truth here (like the part about average horse width — measuring horses was, in fact, my Uncle’s occupation — another good reason to stay in school).


Chet Skwarcan (traffic engineer, author, unique insights) with over 25 years of traffic engineering experience — online help available at TrafficEngineering.com/Services