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Podcast Transcript
When we look at history, we tend to focus on grand things like great leaders and great battles.
In reality, what makes for successful empires is often the mundane: stable laws, an uncorrupt civil service, or, for large sprawling empires, a system of roads.
Roads were one of the secrets to the success of Rome, and they proved useful for centuries, even after the empire’s fall.
Learn more about Roman roads and how they linked together a vast empire on this episode of Everything Everywhere Daily.
The Romans were not what I would call a technically sophisticated civilization. There are very few technical advances or inventions that were made during the almost 2000 years of Rome in its various iterations.
There were some agricultural innovations, especially with plows. Aquaducts, often thought of as Roman, were actually developed by the Etruscians and the Greeks.
That being said, the Romans were excellent engineers. If there was one technical thing they did well, at least by ancient standards, it was building. Their structures can still be found scattered around Europe, the Middle East, and North Africa 2000 years after they were built.
Roman baths were enormous structures with advanced water management and large-scale hot water heating. The Baths Diocleaitan and Caracala can still be seen in Rome today.
Amphitheaters such as the Colosseum in Rome and theaters like the well-preserved one in Orange, France, can still be visited.
All the temples and structures are what draw tourists today, and they serve as visible symbols of Rome.
However, they were not necessarily the most important things the Romans built.
That distinction belongs to Roman roads. Roads are not sexy, but they are vitally important.
When I first started this podcast, I did an episode that was an overview of Roman roads. In this episode, I want to do more of a deep dive to explain exactly what the Romans did to build their roads.
Before I start, I should address the old saying that “all roads lead to Rome.”
This statement isn’t quite true, but it also doesn’t really say much. It actually originated in the Middle Ages during a French poem.
All roads in the Roman Empire didn’t technically lead to Rome simply because they couldn’t cross the Bosphorus Strait. There wasn’t a bridge built across the Bosphorus until 1973.
However, on either side of the Bosphorus, all of the Roman roads were largely connected. That means you could go from modern-day Portugal to Turkey, from Turkey all the way around the Mediterranean to Algeria, and perhaps as far as the Atlantic coast in Morocco.
So what made Roman roads so special, and how and why were they built?
It all started with surveying.
As the roads were designed to move troops and goods as quickly as possible between two points, the Romans tended to build their roads as straight as possible.
Modern-day highways usually go around an obstacle because it is simply cheaper and faster than going through or over it. There are some exceptions, but constructing a gradual bend in a road is more efficient in terms of time and money than trying to go straight through it.
The Romans didn’t subscribe to that philosophy. They would usually dig a tunnel, make a road cut, or build a bridge rather than circumvent something.
If they had to go around something, they would usually make a very sharp turn on the road to get back to the straightaway as soon as possible.
Because the speeds they were traveling at were walking speed, or at best, a galloping horse, they could get away with this.
The primary survey tool they used was called a groma. A groma was designed to create straight lines and right angles.
It consisted of a straight pole that was put into the ground with a single horizontal arm on the top. From the end of the horizontal arm was a cross with four arms, almost looking like a mobile you’d hang over a child’s crib.
Each of the four arms had a weighted plum bomb attacked by a string.
The surveyors, known in Latin as agrimensores, used the groma to ensure that the roads would remain straight over long distances. Another group, known as gromatici, would post rods along the path determined by the agrimensores to make the outline of the road.
Once the route was determined, the next step was to start excavation. Most of the labor to construct a Roman road was usually done by Roman legions. It was a way to keep them occupied when they werne’t actively on campaign, and they were also good construction.
This is what separated a Roman road from a simple path.
First they would then plow the ground to loosen it up, and a team, again usually of legionaries, would then begin removing the soil. They would dig down several feet until they reach bedrock or at least fim soil.
The excavated road was called a fossa, which is Latin for ditch.
What came next depended on where the road was being built and what local materials were available.
They would then fill in the trench start with large pieces at the bottom. This base would mostly be stones and broken pieces of brick and it was called the statumen. This layer would be between 25 to 60 centimeters or about 10 to 24 inches, thick.
On top of the large pieces of rubble would go larger pieces that would mixed to make a very course concrete. This was known as the rudus. It would be about 20 centimetrs or 8 inches thick.
On top of that would be a layer of concrete with fine aggregate consisting of sand and gravel. This would be about 30 centimeters or 12 inches. This was known as the nucleus.
The concrete was Roman concrete, which was made out of a special volcanic ash known as pozzolana.
On top of that would be the final layer known as the summum dorsum. This layer consisted of close fitting paving stones known as pavimentum.
There was more to the road than just these layers. For starters, the top layer crowned slightly so that the middle of the road was the highest point. This was to allow drainage and to preven water from pooling on the road.
On the sides of the road were drainage ditches which were also usually lined with stones. The stones were vertical and created a barrier to help channel water. It served the functional equivalent of a curb in a modern street.
On the sides of the road would often be gravel lined paths which were for pedestrians.
The width of a Roman road varied depending on location and the amount of traffic it had to support. There were some roads that would be the equivalent of a single lane road and others that could support multiple carriages abreast.
If a road was crossing land that was marshy, they would often build a causeway over it. The causeways were built either by piling up a great deal or rock, or by using upright wooden logs, depending on the location.
Every Roman mile, or five thousand Roman feet, there would be a milestone. Milestones usually marked the distance to or from the next destination, but some have been found that just have the emperor’s name at the time of construction.
There were roughly two types of non-military travel along the roads. They were known as cursus rapidi and agnarie. Cursus rapidi was a type of express serves and agnarie was a type of freight service.
The type of vehicles that you would find on the road could be a two-wheeled chariot, a two-wheeled cart in rural areas, or a four-wheeled raeda.
Raeda, for fast transit, might have eight horses but would be limited by weight to about 750 pounds or 340 kilograms.
Most freight could travel at a rate of about 15 miles or 24 kilometers per day.
One of the most important uses of the roads was to send information. The speed that information could be sent at the time was limited to the speed of a horse or a ship.
Official state couriers would travel on horseback and make use of rest houses known as mansions. Riders would go from rest house to rest house and switch horses.
These couriers were the Roman equivalent of the Pony Express. By changing horses frequently, a courier could travel as much as 75 miles or 120 kilometers per day.
According to legend, Emperor Tiberius once traveled 215 miles in a single day in order to get to the side of his brother Drusus, who had been injured. That averages out to only 9 miles per hour if you rode the entire 24 hours without rest, which is possible.
By the second century, the empire had approximately 80,000 kilometers or 50,000 miles of paved Roman roads. To put this into perspective, the United States only had about 47,000 miles of Interstate highway.
In addition to paved roads, there was an additional 400,000 kilometers or 250,000 miles of unpaved roads.
Streets in cities were designed very similar to the roads that crossed the empire, however, there were some differences. Streets in cities were often filled with filth and water.
If you ever visit the ruins of Pompeii, you’ll notice that they have raised stones in the middle of the street. These were so people could cross the street without having actually step in the street.
So, what was the point of this highly elaborate and expensive system of roads?
The road system was the thing that tied together such a large empire.
Roads helped integrate diverse regions into the Roman state by enhancing mobility, trade, and communication. This integration was essential for maintaining control over the Empire’s vast territories.
By boosting trade and allowing more efficient exploitation of resources, roads contributed significantly to the economic prosperity of Rome.
The ease of travel facilitated by the roads helped spread Roman culture, language, and laws, aiding the process of Romanization of conquered peoples.
However, the most important reason for the roads was for the military. The roads were often termed “viae militares” or military roads, during the Republic because they allowed quick and efficient movement of military forces, which was crucial in both expanding and defending Roman territories.
A legion could move about 20 miles per day, marching on the roads. That allowed Roman military force to move wherever necessary in the empire should the need arise.
Surprisingly, we have a very good idea of the layout of theroads in the empire due to a single source, the Tabula Peutingeriana. Also known as Peutinger’s Table, it is an illustrated road map of the Roman world, dating back to the 4th or 5th century but surviving only in a medieval copy made around the 13th century.
All of the time, effort, and money put into the construction paid off. While the roads did require some maintenance, they were extremely durable. Unlike Roman temples and amphitheaters, which became relics and museum pieces, the roads were used for centuries long after Rome was gone.
Arguably, Roman roads were the best-designed roads in the world up until the 19th century. Some roads originally created by the Romans were used as major routes up until the development of the automobile.
Even today, in some places, such as the Via Flamina on the Italian Peninsula and the Fosse Way in Britain, are still used for walking and cycling.
While the materials have changed, modern road-making still uses many of the techniques that were developed by Rome. Modern roads use the layered technique and have roads that are slightly crowned to manage water.
Roads were not just one of Rome’s greatest innovations, but they were largely responsible for its success. They allowed the empire to respond to military challenges, send information quickly, and contributed to its economic prosperity.
They were built so well that they are one of the few things still being used today for their original purpose almost 2000 years after they were constructed.
