Dispelling Some Myths: Romans, Railways and NASA rockets

Yet another urban myth re-appeared on social media the other day, one which regularly does the rounds and has done so for many years since about 1937. In essence a series of connections are made to establish that the huge solid rocket boosters used by NASA had to be transported by rail whose rails were set a certain distance apart, a standard width first determined by the ancient Romans. The historical connections espoused are tenuous at best and do not really stand up to critical thinking. So, having been challenged to provide the real reason we set out to unpack the story and dispel its myths.

If you have not come across this improbable story, it reads like this:

‘The US standard railroad gauge (distance between the rails) is 4 feet, 8½ inches. That's an exceedingly odd number. Why was that gauge used? Well, because that's the way they built them in England, and English engineers designed the first US railroads. Why did the English build them like that? Because the first rail lines were built by the same people who built the wagon tramways, and that's the gauge they used. So, why did 'they' use that gauge then? Because the people who built the tramways used the same jigs and tools that they had used for building wagons, which used that same wheel spacing. Why did the wagons have that particular odd wheel spacing? Well, if they tried to use any other spacing, the wagon wheels would break more often on some of the old, long-distance roads in England. You see, 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 (including England) for their legions. Those roads have been used ever since. And what about the ruts in the roads? Roman war chariots formed the initial ruts, which everyone else had to match or run the risk of destroying their wagon wheels. Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing. Therefore, the United States standard railroad gauge of 4 feet, 8½ inches is derived from the original specifications for an Imperial Roman war chariot. Bureaucracies live forever. So the next time you are handed a specification, procedure or process and wonder 'What horse as come up with this?', you may be exactly right. Imperial Roman army chariots were made just wide enough to accommodate the rear 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 in 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, and 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.’

The sentences highlighted above in bold are specifically intended to draw attention to the somewhat flawed history that perpetuates this myth. So, with that in mind, let us start with the first premise leading to the amazing conclusion about NASA:

‘…the first rail lines were built by the same people who built the wagon tramways, and that's the gauge they used.’ 

Inconveniently, according to Bertram Baxter a standard gauge for horse railways never existed (Baxter, 1966). In the north of England, for example, none of the horse-drawn tramways had a gauge of less than 4 ft (1.219 m) but most varied in width. Baxter cites that both John Blenkinsop's Middleton Railway and the Wylam colliery's system, the latter being built before 1763, had a gauge of 5 ft (1.524 m), while the old 4 ft (1.219 m) wide plateway was re-laid to 5 ft (1.524 m) so that Blenkinsop's engine could be used (Baxter, 1966). A wagonway in Beamish had a gauge of 4 ft 4 in (1.321 m) or 4 ft 7½ in (1.410 m) while that of the Bigges Main Wagonway in Wallsend was 5 ft 7½ in (1.7145 m), the same as the nearby newly laid Kenton and Coxlodge wagonway to which it connected (Baxter, 1966; Tyne and Wear HER(1128)). So, the wagonway builders did not fix on a standard gauge. Instead, the online ‘Britannica’ entry states George Stephenson, English engineer and principal inventor of the railroad locomotive, was responsible for introducing the first standard:

 ‘About three-fifths of the rail trackage in the world is the so-called standard gauge of 4 feet 8½ inches (1.435 metres), which originated with George Stephenson’s pioneer Liverpool & Manchester line in 1829 [1]. It was exported from Britain to Europe and the United States with the export of British locomotives built to it.’

Among the notable deviations to this standard was the broad-gauge railway introduced in 1833 by Isambard Kingdom Brunel when he was appointed chief engineer to the Great Western Railway. Brunel solution was to set the rails 7 ft ¼ in (2,140 mm) apart, hence ‘broad gauge’. This innovation made higher speeds possible which in turn stimulated railway progress but also provoked the famous ‘Battle of the Gauges’. Ultimately the standard gauge won out.

Other notable deviations are Russia’s 5 ft (1.5 m) gauge, Spain’s 5 ft 6 in (1.7 m) gauge, and Japan’s 3 ft 6 in (1.1 m) gauge. Several countries operate railroads on two different gauges; Pakistan operates on three while Australia and India use four.

It is worth noting that if the standard gauge ‘originated with George Stephenson’, then this seemingly negates any ancient Roman involvement. Moreover, note that when Spain built their first railways, they adopted a gauge nearly one foot wider than the supposed Roman ‘standard’ wheel gauge. Given that Spain had a much longer history as part of the Roman Empire than Britain, why would the Spanish have deviated from the much-vaunted standard?

Returning to the story, the next argument is that cartwrights building the wagons had to use a gauge of 4 ft 8½ in (1.435 m) because:

‘…if they tried to use any other spacing, the wagon wheels would break more often on some of the old, long-distance roads in England.’

Why would the ‘wagon wheels break more often’? Presumably cartwrights and wheelwrights were skilled professionals. It seems highly unlikely that they could not build robust wagons with strong wheels that could cope with different spacing. Moreover, the argument does not allow for an ancient army’s chariots or carts moving cross-country over rough terrain where no road or track existed. But let us consider the rutted roads for a moment. The story assumes that the Roman’s standard gauge, which we have seen is a fallacy, led to roads with wheel ruts set a specific distance apart [2]. On the face of it this is indeed plausible, but surely the degree to which a road becomes rutted is linked to the volume of traffic using it. Even as late as the first quarter of the 20th century, roads were not subject to the amount of traffic witnessed today. Thus, wear and tear on the metalled surface was probably less pronounced than one might expect. Were wheel-ruts in 18th century British roads therefore such a problem? Moreover, it seems odd to assume that roads were not repaired, even resurfaced. If roads were allowed to become ever more deeply rutted, one can envision the absurd consequence that eventually wagon axles would foul on the raised centre section between the ruts. This would hardly be conducive to travel, and road users would probably demand improvements - who would pay for them is another matter.

Interestingly, in many period dramas the example image shown right is intended to portray an ancient trackway or an old road. Inconveniently, however, the visible wheel ruts and, most significantly, the central grassy ridge result from the track’s use by modern wheeled vehicles. The bare earth is not the problem since this is what one might expect were the track to be repetitively used by, for example, pedestrians or animals - the surface would be worn away somewhat uniformly. The problem is the grassy ridge. This can only be formed by something with a wheelbase that wears away the surface either side but leaves the centre line untouched. Were a wagon drawn by a single horse, or a pair of horses as stated in the story, to regularly use this track, then even the grassy area would be worn away by the action of the horse’s hooves. So, while these country trails look old, they are in fact a product of modern vehicles.

To rebuke the next fallacy we can combine the following three highlighted sentences and deal with them collectively:

‘Roman war chariots formed the initial ruts…Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing….derived from the original specifications for an Imperial Roman war chariot.’

The nonsense states that the Romans had ‘war chariots’ and it was the wheel gauge of these that set the standard across the Empire. Unfortunately for this deceptive tale, by the time the Romans had expanded their Empire across much of Europe, the near East and North Africa, chariot warfare was very much a thing of the past. It is true that chariots were initially used in ancient warfare during the Bronze and Iron Ages, but after its military capabilities had been superseded by light and heavy cavalry, chariots were relegated to being a mode of transport or used in triumphal processions, and for racing. That said, Britain may have been an exception providing Caesar’s Commentaries are an accurate reflection of what he observed during his first foray across the Channel in 55 BC. If we take Caesar at face value, then the Britons may well have kept using chariots long after most other armies had dispensed with them in favour of cavalry horses. But equally, Caesar’s writing is highly political and intended for a home audience and, like many other Roman authors, Caesar may well have drawn attention to the Britons’ chariot use to highlight their barbarity and backwardness to his readers.

The subsequent two sentences imply that the Roman army had, firstly, conceived a design ‘specification’ for a weapon they did not use and that, secondly, had they built war chariots then they would all be alike. This is a wonderful example of attributing the idea of a modern design bureau and manufacturing practices to an ancient civilisation, however. Yet it is true that by the late 4th century AD, the production of arms, armour, and military equipment was centralised into state-owned factories/armouries known as fabricae. Although the origin of the system and its administration is unclear, it was likely codified during the reigns of either Diocletian (AD 284 to AD 305) or Constantine (AD 306 to AD 337). Note, however, that this system was operating in the late Roman period centuries after war chariots had disappeared from the battlefield.

The fabricae were dispersed throughout the Empire’s provinces and were responsible for producing the vast array of the army’s equipment. Some fabricae specialised in the production of certain types of equipment such as artillery, cataphract armour [2], bows, and swords. Inconveniently for the anecdote, war chariot production is not mentioned. Yet even with state-run factories, Roman soldiers certainly would not have presented a uniform appearance since the goal of the fabricae was not to ensure blanket uniformity, but rather to centralise the production of military equipment under Imperial control, and to ensure quality of production. While certain basic equipment, like javelins and arrows, were likely produced by unit armourers, worn-out clothing and footwear would have been replaced by local produced items, so it is highly likely that Roman soldiers would have had a local flair and appearance. Importantly, as most objects were predominantly handmade, the quality of materials used, specific dimensions, the fit and finish can all show variation between manufacturers. Even if the Roman army operated state-owned factories or employed official contractors, it is evident from the differences that, once again, there was no standard design as we might understand it today.

The next statement is an adaptation of the bureaucratic standardisation argument:

‘Imperial Roman army chariots were made just wide enough to accommodate the rear ends of two war horses.’

We have already debunked the notion that the Roman army used ‘war chariots’, but it is fair to say that they did employ wagons to transport heavier or bulkier equipment, for example siege engines, catapults and stone-throwers. Nonetheless, these wagons were more likely drawn by teams of oxen rather than horses as the latter would be far more useful as cavalry mounts. That said, chariots were still used in the Roman era albeit for racing, especially in circuses, or for triumphal processions. A chariot pulled by four horses abreast was called a Quadriga, from the Latin quadriugi (‘of a team of four’). Sometimes the term simply referred to the four horses without the chariot, or just the chariot. A three-horse chariot, or the three-horse team pulling it, was a triga, from triugi (‘of a team of three’), and a two-horse chariot, or the two-horse team pulling it, was a biga, from biugi. Of note, the chariots portrayed in the epic film ‘Ben Hur’ (1959), pictured below (top left), and the reconstructions favoured by some of those who recreate chariot racing for modern audiences are far too heavy and bulky. These versions would be far more at home in a triumphal procession through Rome than in the circus.

Based on images such as the mosaic shown above (top right), a Roman racing chariot was reconstructed in 2005 as part of a Time Team special on the rediscovery of ‘Britain’s Lost Roman Circus’ in Colchester, Essex (above: bottom left and right). Such chariots were fast, light, open, two-wheeled carriages typically drawn by two or more horses hitched side-by-side to a yoke itself attached to a single, central draught pole. As shown the charioteer stands unsupported in this case on a lattice of rawhide leather straps bound tightly to the chariot’s wooden frame. The frame itself extends upward to form a waist-high guard at the front and somewhat to the sides which is also of stretched rawhide. As one of the ‘Roman’ supporting artists for the filming, the author has handled this reconstruction and can attest that it is incredibly lightweight and can be lifted and manoeuvred with one hand.

Significantly, the evidence from contemporary frescoes and mosaics, and from the chariot that once belonged to pharaoh Tutankhamun discovered in his tomb (shown right), confirm that ancient Egyptian, Greek, Roman and even British chariots were very obviously all designed with a central draught pole to which two or more horses were attached via a yoke and harness. So once again the notion that ‘Imperial Roman army chariots were made just wide enough to accommodate the rear ends of two war horses’ is clearly not true. One need only compare the width of the four horses with the reconstructed racing chariot pictured above to appreciate the fallacy. Indeed, if the two outermost horses are removed and the chariot becomes a biga, then the chariot axle is still wider than the width of the remaining two horses. Being generous for a moment, the wording suggests that whoever concocted the story may well have confused chariots with carts that use a pair of shafts, one along each side of a single draught animal (typically an equid such as a horse, mule or donkey). If so, then this might explain why it is claimed (albeit erroneously) the wheelbase had a standard width the equivalent of two horses.

And finally…

And finally, we arrive at the conclusion regarding NASA solid rocket boosters, or SRBs, whose dimensions were dictated by the US railroad’s track gauge, a descendent of Roman chariot design. In answer to an online question about ‘How fair is the claim that Shuttle boosters diameter was dictated by the railroad gauge?’, Michael Borgwardt’s reply of March 22nd, 2014 is reproduced and deserves reading:

‘The claim may be based on a misunderstanding. The solid rocket boosters were made in Utah and transported to the launch site in 4 segments by rail, which did limit their size. But it was not the track gauge that influenced this limit, but the loading gauge [4], which is only very indirectly related to the track gauge.

However, the diameter of the shuttle boosters (12 feet) exceeds the width of all loading gauge standards in the USA (which differ mostly in height, the width is generally 10 feet 8 inches). Shipments that exceed the standard loading gauge in width are not all that uncommon, more mundane industrial parts often exceed them, but it requires careful planning and is very expensive as it often involves temporarily dismantling blocking structures, and of course at some point (such as with a tunnel) you run into hard limits.

So, it doesn't look like transport by railroad dictated the booster designs, but it probably influenced them. I'm pretty sure that if making them wider would have yielded some large advantage and been otherwise feasible, then a solution to the transportation problem would have been found.’

It is difficult to argue with Mr Borgwardt’s logic. So, what can we conclude? This popular myth has been around since at least 1937. It alleges that the origin of the 4 ft 81⁄2 in (1,435 mm) standard railway gauge can trace its origins seamlessly to Roman Empire pointing to the evidence of rutted roads that are claimed to have been made by chariot wheels. Supporters of the idea are encouraged by the fact that the otherwise peculiar distance is almost exactly 5 Roman feet. Unfortunately, there is no evidence to span the millennium and a half between the departure of the Romans from Britain and the adoption of the gauge on the Stockton and Darlington Railway in 1825. Moreover, as Michael Borgwardt argues the design dimensions of NASA’s SRBs were dictated by the US loading gauge and not the width of nation’s railroad tracks.

For an alternative take on this subject, then David Mikkelson’s article published on April 16th, 2001 on Snopes.com is certainly worth a read (Mikkelson, 2001). Bon appétit!

References:

Baxter, B. (1966), ‘Stone Blocks and Iron Rails (Tramroads)’, Industrial Archaeology of the British Isles, Newton Abbot: David & Charles.

Mikkelson, D., (2001), ‘Are U.S. Railroad Gauges Based on Roman Chariots?’, Snopes.com, Available online (accessed October 12th, 2023).

Tyne and Wear HER(1128): Bigges Main Wagonway - Details, TWsitelines.info, Available online: accessed September 26th, 2023.

Endnotes:

1. Following the success of the Stockton & Darlington Railway in 1825, the cities of Liverpool and Manchester decided to build a 40-mile (64-km) steam-operated line connecting them. George and Robert Stephenson were entrusted with constructing the line, but a competition was held to choose a locomotive. The Stephensons’ pioneering railway locomotive ‘Rocket’ won against three rivals, including an entry by John Ericsson, who later designed an armoured vessel called the Monitor for the federal forces during the American Civil War. For a short stretch the Rocket achieved a speed of 36 miles (58 km) per hour.

2.  The gaps in the pedestrian crossings in Pompeii could give credence or otherwise to this statement, but no relevant studies appear to have been made.

3. Equites cataphractarii, or simply cataphractarii, were the most heavily armoured type of Roman cavalry in the Imperial Roman army and Late Roman army. The term derives from a Greek word, κατάφρακτος kataphraktos, meaning ‘covered over’ or ‘completely covered’.

4. A loading gauge is a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads.