Dr. A. Trevor Hodge  -  "Roman gauge"


8 June 2001


Daniel Bowen, from Melbourne, Australia, wrote:


"A debunking of this happened to come my way yesterday:

"Every year or two someone puts forward the proposition that "standard gauge" is actually based on a Roman military standard.

The thesis goes like this:

The standard gauge of North American railways is based on that of early British railways. That standard gauge was set by George Stephenson in the 19th century: he built the Stockton & Darlington line and urged that other lines be built to the same gauge. He set his rails based on the distance between the wheels of the mine wagons that were in use on plate-ways in and around the coal-mines in that area. Those wagons were based on the local agricultural wagons. They in turn (so goes the thesis) were equipped with wheels-sets that would run in the grooves in the Roman roads that still existed (well, the rights-of-way still existed) leading to Hadrian's Wall. The grooves had been worn by Roman chariot traffic. And so, the gauge of our trains was actually set by a Roman military specification.

Two years ago I visited Coninbraga, an excavated Roman town in Portugal. Going through the arched gateway into this fortified town, there were indeed grooves in the paving stones, so I attempted to measure the "gauge": would it be close to standard gauge, or to the Portuguese/Spanish gauge?

What I found was that there were so many grooves, that by choosing an appropriate pair, one could find any gauge from about one metre to about two metres!

Wondering about this, I recently I wrote to Dr. A. Trevor Hodge, Professor Emeritus in the Classics department at Carleton University, Ottawa, Canada. He has written extensively about technology in classical times (e.g. in Scientific American) and has published articles on railway topics. His reply is copied below, and he gave permission for it to be posted here:


"The story that you retail to me about the standard British rail gauge of 4' 8.5" being based on grooves worn, or cut, in the paving of Roman roads is indeed a hoary old chestnut, familiar to all railway historians. Let us get rid of the easy bit first.

There is no question of the gauge being based on the grooves worn by Roman chariots, because the Roman army did not have chariots.

Other countries did, but in the Roman Empire the only time you ever saw a chariot was as a ceremonial conveyance in a triumphal procession in Rome. The army didn't use them. And even non-Roman chariots were not likely to wear ruts in stone, for, in the interests of speed and manoeuverability, you made them as light as possible, so that they rather resembled the sulky used in modern harness racing. Not much chance there of wearing grooves! In fact, so fragile were they that with Greek chariots the first thing you did when you got home was to remove the chariot's wheels, like the wheels of a modern racing bicycle, to take the strain off them.

Now, for the origins of the gauge. That was certainly based on the width of existing tram-roads and plateways in the mines of the North of England, and there seems no doubt that that reflected the standard size of ordinary carts. Carts usually did come with their wheels about five feet apart, not because of anything in the roadway, but because that suits the size and proportions of the horse. So the "Oxford Companion to British Railway History" (Oxford, 1997), page 523.

As for grooves in Roman roads, there are hardly any. I would dearly like to see some of these enthusiasts from Northumbria or Durham actually go out and look at some of the Roman roads in the area of the early railways, for it doesn't sound as if they have ever done it. In fact, grooves (usually cut, not worn) are found commonly in only two places. One is the road from a quarry, where the heavily laden carts may have to cross a stretch of bare rock, and there are grooves to keep them steady. The other is Pompeii, where the roadway was often crossed by rows of stepping stones for pedestrians, with grooves between them for wheeled traffic. I do not know of anyone who has made an actual detailed study of their gauge, and the publications are unreliable, for you often don't know whether they are measuring from the inner edges of the grooves or the middle. And in any case, as you found, there is very great variation in the gauge of the grooves.

In short, the whole story of the Roman origin of the rail gauge is a nice story, and repeated ad infinitum just because of that, but a nice story is all it is. There is no demonstrable truth to it at all!"


So there you are - another good myth laid to rest.

Dewi Williams
Kanata, Ontario, Canada"


Daniel Bowen,
Melbourne public transport FAQ   -  http://www.custard.net.au/melbtrans/


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