Question about paved Roman roads

[Viggen]

This is a post I came across on Google Plus i got the permission of the author Mark Keith to repost his questions here...

 

 

I am looking for good sources of information to answer particular questions I have about ancient, paved Roman roads such as those found in parts of Rome, the Appian Way, and Pompeii. I have often walked along or across these roads, paying particular attention not to turn an ankle or fall on my face. All the while I think that the roads must certainly have been more pedestrian-friendly in the ancient world. Here are my thoughts and questions:

 

1) While some weathering has certainly occurred over the centuries to round these stones, they could not have changed very much. The roads paved in large stones in Rome are very similar to those unearthed in Pompeii the past few centuries. Is it possible or even probable that sand, gravel, concrete, or other aggregate (or some combination) was added to "smooth" the surface of the road? When Pompeii was excavated, could this top layer have been removed and swept away? Could the exposed roads in Rome and the Appian way have had their surface smooted by aggregate weathered away?

 

 

2) I have come across conflicting information about the ruts found in the ancient roads in Rome and Pompeii. Some sources say they were worn by the continuous passage of wheeled traffic. The ruts became prominent particularly as traffic edged between those large stepping stones which allowed pedestrians to cross from one side of the road to the other without stepping in something unpleasant. Other sources say that the ruts were deliberate in order to guide the traffic more easily between the stones or around certain curves or other obstacles. Which is true? Looking closely, the ruts seem to appear mostly between the stepping stones and at intersections.

 

3) Back to those stepping stones in Pompeii. Are they found at any other sites? I can see how the wheels of carts would pass between the stones, but if these carts were pulled by oxen, donkeys, mules, and horses, how did the animals navigate these obstacles? Certainly the steeping stones and ruts would provide dangerous navigation for animals? Were the carts pulled or pushed only by humans who carefully picked their way down the street? If these ruts are made solely by wear and tear, were they filled in with sand, stones, etc? (See comment above)

 

4) Finally, I have also read conflicting reports on the purpose of those stepping stones in Pompeii. Some say they were solely for foot traffic. Others say that they acted as "speed bumps" to slow wheeled traffic. Perhaps some combination? Also, were the streets in Pompeii deep so that dirt, waste, etc. could be collected (and washed/swept away) and kept from foot traffic, or were the streets deep in order to protect pedestrians from wheeled traffic.

[Auris Arrectibus]

@1.

 

There were mainly two kinds pavimentum of roads:

- lime-stone or basalt

- grit

 

Lime-stone or basalt blocks were the summum dorsum:

Blocks fitted on top of moist concrete, so the spaces between them were not empty at that time.

 

 

 

Jeroen H de Lange,

Amsterdam

[GhostOfClayton]

I seem to remember the stepping stones were also present in Herculaneum.

[Melvadius]

IIRC the 'stepping stones' in Pompeii (I don't remember any in Herculaneum but its been a few years now) are all on roads which slope uphill and it appears that several of the public fountains had the facility or were designed to over-flow I believe intentionally to help keep the streets clean.

 

Possibly rather than being intended to close off parts of the town these stone steps were a purely functional aspect of 'street furniture' allowing people to cross the deep roads when there was a lot of water filling them up.

 

I suspect similarly it was mainly carts drawn by two animals which were used and if so then they probably could get through the 'stepping stones' using the same spaces as the wheels.

[Dickonbard]

I am writing a general history of transport from the Neolithic to the present, which includes a chapter on Rome. One of the questions I am struggling to find an answer to is how the road network accommodated riders on horseback. The hard surfaces of paved roads, which are ideal for marching troops or ox-carts, are much more difficult for a galloping horse. Yet there is plenty of evidence of the speed with which messages could be transmitted in urgent cases. It would be better for the horse if there were a separate track alongside the paved road. But is there any evidence that this was ever provided?

[GhostOfClayton]

It's important to remember that the surface of most Roman metalled roads would have been flattened by mortar, or well bedded in gravel. They weren't the bumpy surfaces you see today, now that the softer materials have eroded. I'm not a horse rider, but I imagine that would be akin to a gallop along a modern road.

 

Also, that's just the metalled roads. A significant number of major trunk roads were little more than a gravel wearing course on a compacted soil base course (with good drainage measures). In the modern UK, a horse would b*gger that up pretty quickly, but, in the Med, the ground tends to be harder, the hoses were smaller, and I can't comment on how widespread the use of horseshoes was. Anyone?

[Melvadius]

...I can't comment on how widespread the use of horseshoes was. Anyone?

 

The British Museum mentions has this article on hipposandals which were a form of temporary horseshoe mainly used by draught animals but includes a comment regarding horseshoes:

 

Nailed horseshoes were known but rarely used by the Romans. Much more common were iron hipposandals, a form of temporary shoe that could be fastened to the hoof for use on metalled roads and easily removed when not required. Hipposandals were probably intended for draught animals: horses, ponies or mules. Because the animal's hoof exerted great pressure, they had to be made from thick metal. The underside was often given a tread to increase the animal's grip on the surface of the road...

 

BTW regarding riding on Roman roads I believe that while the road area was usually bounded by ditches this wasn't always the case. In addition even where there were ditches the actual distance between them varied enormously and there were usually strips of land on either side of the raised agger which were only lightly metalled so probably intended for the use of animals.

 

There is some information on construction techniques at the Birmingham Roman Roads Project here [Edit the links page is probably most relevant as it inlcudes several specifically relating to roads in Italy] although there are also several very good reference books out there as well.

[GhostOfClayton]

Also worth a mention, though how relevant it is, I don't know. The Military Way, which was the 3rd Century road built to run next to (and south of) Hadrian's Wall, is considered not to have been design for horse traffic at all due to steep gradients. Possibly, the surfaced road was for infantry movements, and the cavalry/horse traffic were expected to use the sides and/or the surrounding open country.

[Dickonbard]

Thank you, GhostOfClayton and Melvadius, for these quick and helpful responses.

 

I had worked out that metalled roads would have had an upper surface that was a lot smoother than the ones we see today. A mortar/gravel overlay, giving a hardness of surface comparable to that of a modern tarmaced road, sounds about right. It would work well for marching troops, ox-drawn wagons and for horses ridden at a walk or a gentle trot. It is hard enough to keep the rolling resistance between the surfaces of wheel and road to an acceptably low level, whilst giving the draught animal an acceptable degree of traction.

 

The physics of rolling resistance is quite complex, but well understood. In contrast, the question of the impact of hoof on road surface has, understandably, attracted much less interest on the part of scientists or engineers. However, from Eadweard Muybridge's amazing photographs onwards, we have been able to understand how the gait of the horse changes from walk to trot to canter to gallop. At a walk, the horse has three feet almost permanently on the ground and moves the fourth leg. At a canter or gallop, there is a point at which all four legs are off the ground, followed by a point at which the horse brings down one of its hind legs to start propelling itself forward - and this is the point of maximum impact. A single hoof (supporting a horse and rider with a combined weight of over 400kg, even allowing for the smaller size of Roman breeds) hits the surface hard. That's a lot of energy to be dissipated. If the surface is soft, the energy will b*gger up the road, as GOfC puts it. If the surface is hard, it will b*gger up the horse.

 

Horses evolved on the North American prairies and migrated to the Steppes of Asia. Their hooves have therefore evolved to deal with the relatively firm surfaces of comparatively arid grasslands. In the parlance of horse-racing, they like the going to be 'firm to good'. A canter or gallop on a tarmaced road would carry a high risk of fracturing the hoof.

 

But I think Roman messengers could achieve distances of up to 300km a day (I

[Melvadius]

Thank you, GhostOfClayton and Melvadius, for these quick and helpful responses...

 

You are welcome. Glad you found them useful.

 

I had another couple of thoughts whihc you may have covered already in your research but just in case; if you haven

[GhostOfClayton]

. . . and for completeness of this discussion, I shall copy and paste your posting from another thread, Dickonbard.

 

"I have several times written to you that I have bought about five thousand modii of ears of grain, on account of which I need cash. Unless you send me some cash, at least five hundred denarii, the result will be that I shall lose what I have laid out as a deposit, about three hundred denarii, and I shall be embarrassed. So, I ask you, send me some cash as soon as possible. The hides which you write are at Cataractonium - write that they be given to me and the wagon about which you write. And write to me what is with that wagon. I would have already been to collect them except that I did not care to injure the animals while the roads are bad."

 

The problem of getting supplies, money to pay for them and the means to transport them aligned is obviously a perennial one!

 

Vindolanda Inventory No. 88.946, accessed at Vindolanda Tablets Online

 

The last sentence (whilst clearly dealing with a cart rather than horse and rider) does tend to suggest that roads sometimes broke up making them dangerous for animal traffic. Also, because he says roads (plural) rather than a specific road, it does suggest a seasonal problem affecting the network.

 

My impression of the Cursus Publicus is of a network of riders that rode to the next station and back, passing a mail bag to the next man, rather than the same man changing horses. that way, a handover can be effected more quickly, and the rider stays on roads he (and the horse) are familiar with. A side benefit of that familiarity may be the ability to ride a little further in failing light. Even then, it's still quite an achievement.

Edited March 15, 2012 by GhostOfClayton

[Dickonbard]

The Wikipedia article on the Cursus Publicus quotes Suetonius on the founding of the service by Augustus:

 

"To enable what was going on in each of the provinces to be reported and known more speedily and promptly, he at first stationed young men at short intervals along the military roads, and afterwards post-chaises. The latter has seemed the more convenient arrangement, since the same men who bring the dispatches from any place can, if occasion demands, be questioned as well."

 

The article goes on to suggest that "the relay system was displaced by a system in which the original messenger made the entire journey". I find this implausible. Like GhostOfClayton, I envisage most of the official correspondence carried by the Cursus Publicus travelling by bag. I can't imagine, for instance, that Pliny's slightly self-serving requests to Trajan for guidance needed to be carried by messenger. The same goes for requests for imperial rescripts, etc.

 

However, we all know that there are cases where a mere written communication does not suffice. For my book, I'm using the example of the murder of Pertinax on 28th March 193 and the subsequent auction of the Empire won by Didius Julianus. Septimius Severus, who was 1,100km from Rome at the time (in Carnuntum), allowed the XIV Gemina to hail him as imperator on 9th April. I think two things happened in the 12 intervening days. One is that Severus had got the news of developments in Rome - a written message would suffice here, provided it was from a trusted source, although a messenger who could report on the mood in Rome would be better. The other is that Severus probably sounded out colleagues about their support if he made a 'bid for the purple'. If messengers could manage 300km a day, they could have brought him responses from Germania Superior, Raetia, Noricum, Pannonia Superior and Moesia Superior, telling him the positions of six of the nine governors and 10 of the 16 legions along the frontier. But, for this purpose, written messages would not suffice. Severus would want to send trusted messengers who could answer supplementary questions, and also read the body language of their interlocutors.

 

As an aside (just because I think it's such a wonderful resource), the NASA website says that there was a full moon in 193 on 4th April, so messengers or couriers could have ridden by night!

[Dickonbard]

Looking at it a little harder, the section of the Wiki article on the speed of the Cursus Publicus must be wrong. It quotes Procopius, where he is disparaging Justinian by saying how much better things were run in the good old days:

 

"The earlier Emperors, in order to obtain information as quickly as possible regarding the movements of the enemy in any quarter, sedition or unforeseen accidents in individual cities, and the actions of the governors or other persons in all parts of the Empire, and also in order that the annual tributes might be sent up without danger or delay, had established a rapid service of public couriers throughout their dominion according to the following system. As a day

[Melvadius]

Looking at it a little harder, the section of the Wiki article on the speed of the Cursus Publicus must be wrong.

 

My mistake in citing it but it looks like you may have some updating of Wikipedia to do when you complete your research

[Dickonbard]

Not at all, Melvadius. Wiki's an invaluable starting point. I'd already glanced at this page myself without spotting the problem. It was only when you pointed me back to it that I looked at it a tad harder!