The roads of ancient rome are one of the most durable remains of that ancient civilisation – they were certainly one of the most significant components of the mighty infrastructure and civil engineering capability which enabled the Roman empire to flourish. The construction of the intricate network of Roman roads had a huge impact for the Roman economy – not dissimilar to that which western society witnessed with the construction of railways in the 19th century.
As already mentioned in our introduction to roman roads, the construction of a road network was a lengthy and expensive process. Perhaps a very good extant example of how “Rome wasn’t built in a day”. Furthermore, the roads were not all as we imagine them today: they would often begin their existence as beaten tracks, which were only paved at a later time and only very gradually.
The building of Roman roads was often planned and undertaken by the Roman military engineers, particularly in terms of the outer reaches of the empire, starting with the roads in Gaul, built under the command of Agrippa between 16 and 13BC. The building work itself would be undertaken by the soldiers themselves or by captives and local workforce they might access. The materials employed were usually those which were most readilly available, ie stone such as neatly shaped granite slabs was not always readily available!
A number of elements were fundamental to Roads in ancient Rome:
- Access to materials for their construction and maintenance
- Ease of use (ie avoid flooding, little breakage of carts or twisted horse ankles)
- Ease of control and supervision
- Enable fast transit, particularly for troops, so as to allow a larger area to be controlled with fewer troops
- Enable access to provisions and resting points.
It is therefore easy to imagine a site such as Hadrian’s wall to be backed up by a significant road network, which actually wasn’t only useful to the military contingent but also to the population centres and trade which throve around them. It is therefore easy to see how a Roman road was not only a means of enabling efficient “military control” but also of “romanisation” and a strong catalyst for the “pax romana” and growth in the local economy.
The above is not only true of Roads in the provinces: whilst the appian way is considered as the “first” Roman road with an engineered regular course (312BC) we know that it was preceded by other important roads such as the “Salaria” (the salt road) and the “Tiberina”, both of which followed the course of the River Tiber and its valley (see ancient Rome’s geography). These two roads are evidently tortuous and trace the course of roman influence throughout the region, whilst the Appian way is a clear demonstration of Roman planning and methodical administrative foresight.
We know from Cicero that the construction and maintenance of roads had its own specific administrative system placed under the control of the Censors (elected roman magistrates). However during the rule of theroman emperors this control was shifted. In particular from the age of Emperor Domitian when the decision to construct new roads was an imperial prerogative.
Construction techniques of Roman Roads
The construction approach of Roman roads was influenced by three principal factors:
- Logistical-Political-Military needs
- Road classification (perhaps a subset of the point above)
- Resources available (monetary as well as readily available materials)
Roman roads could be of four types:
i. “viae publicae” – public roads built at public expense (taxpayer’s money or war booty)
ii. “viae militares” – military roads, built by the army at their own expense but would eventually fall into the first category of public roads.
iii. “actus” – minor roads, built and maintained by local councils
iv. “privatae” – yep, private roads built by private individuals at their own expense within their private property.
Construction of ancient roman roads would start by laying out a flat surface over which a “statumen” layer of debris would be laid and pounded in order to provide both a solid foundation as well as drainage. This first layer was then covered with a thick layer of sand, possibly mixed with clay. This layer could be as much as 1m in thickness (approx 3ft) although a layer in the region of 20-40cm would be more usual (up to 1ft). This would then be covered by the road surface itself, if available this would include large stone slabs laid out with a curved convex surface to aid water drainage to the sides. Titus livius (“Livy”) tells us that around 170 BC roman roads were paved within the cities but unpaved in the coutryside: It seems paving made it’s debut around the 2nd century BC although the appian way gives evidence of paving as far back as 296BC (ie 3-4th century BC) for a brief length of road just outside the walls of Rome.
Clearly such materials and ideal surface were not always available, for example building a road across a marshy area posed engineering problems of its own, such as a need for drainage and hydraulics (which roman engineers were experts at since the earliest days of ancient Rome which was itself built in a marshy area) and altered construction methods, such as the use of wooden beams and rails, rather like a modern railtrack over which a layer of stone slabs and a layer of clay/sand could then be laid.
The width of Roman Roads
The width of the road would be planned to allow horses and cariages along it or where it was too narrow such as on a mountain pass, regular side-stops would be planned to allow transit.The width of roads varied with the importance of the road: A width of 3m or over (9ft) was normal for roman roads to allow to carts to drive past each other in opposite directions although road widths as great as 7m (21ft) have been found. The edges of the road would be closed off by stones placed lengthways, which in city centres would act as the step for pavements. In cities such as Pompeii
and Osita the roads have been found to be a relatively consistent 4m (12ft) in width for major roads
, with a further 4 meters worth of pavements ie 2m either side). Minor roads in the city were anywhere between 2 and 4m (6-12ft).
It is interesting to note the ruts worn into Roman roads by the regular passage of carriages which were evidently built to standard width in the region of 1.3m (4 ft). It also seems that the ruts were not always worn by use but at times actually applied in instances such as steep or very tortuous mountain roads, rather like laying tram lines to render the roads more secure for the carts which might otherwise slip over the edge.
Roman Roads as part of large scale infrastructure
Roman roads were clearly an important element of a more elaborate set of infrastructure which was a pillar of the Roman economy. The roads weren’t subjected to the same limitations of water transport and Roman aqueducts required access to a broader set of construction techniques: Roman aqueduct construction techniques nevertheless the aqueducts were often built close to the roads (for obvious reasons). It will come as little surprise that the first Roman aqueduct was also named after Appius Claudius, who was responsible for the Appian road.
Roman engineers tended to plan their roads so that they should follow the easiest as well as straightest route, rather like a skier would follow an ideal fall line down a ski slope rather than going absolutely dead straight. Roads aren’t subject to the same constraints as water transport, hence allowing steep slopes to be followed if absolutely necessary rather than difficult tunneling. Nevertheless this doesn’t mean there are no examples of great Roman bridges or tunnels, a notable example being the one built by an architect under the reign of Augustus whom Strabo tells us was called Cocceius between Naples and Puteoli (bay of Naples, relatively near Pompeii) with a length of just over 700m, 4 wide and 5 high.
Seneca (epistle 57 to Lucilius: “on the trials of travel”):
“When it was time for me to return to Naples from Baiae, I easily persuaded myself that a storm was raging, that I might avoid another trip by sea; and yet the road was so deep in mud, all the way, that I may be thought none the less to have made a voyage. On that day I had to endure the full fate of an athlete; the enointing with which we began was followed by the sand-sprinkle in the Naples tunnel. No place could be longer than that prison; nothing could be dimmer than those torches, which enabled us, not to see amid the darkness, but to see the darkness. But, even supposing that there was light in the place, the dust, which is an oppressive and disagreeable thing even in the open air, would destroy the light; how much worse the dust is there, where it rolls back upon itself, and, being shut in without ventilation, blows back in the faces of those who set it going! So we endured two inconveniences at the same time, and they were diametrically different: we struggled both with mud and with dust on the same road and on the same day.
The gloom, however, furnished me with some food for thought; I felt a certain mental thrill, and a transformation unaccompanied by fear, due to the novelty and the unpleasantness of an unusual occurrence….”
Building roman roads across broad countrysides, at times in difficult terrains implied a broad range of engineering capabilities and the best of ancient Roman technology: ancient roman bridges and bridge construction techniques, roman engineering, building methods, roman building materials, roman arches all of which was to enable roman transport and roman trade!