Roman Empire's 300,000 Kilometer Road Network: New Research Reveals Unprecedented Scale of Ancient Infrastructure

Itiner-e map integrates critical components from Stanford University's Orbis interface for enhanced understanding of ancient transportation.

Sydney:

The Roman Empire at its zenith encompassed approximately 5 million square kilometers with a population of around 60 million inhabitants. This extensive territory and massive population were connected through an intricate network of long-distance roads linking locations separated by hundreds or even thousands of kilometers.

Roman roads were considerably more sophisticated than modern counterparts. Their construction involved multiple layers of materials extending one to two meters below the surface, with roads in Italy being paved with volcanic rock or limestone for durability.

These roads featured milestones indicating distance measurements, which proved invaluable for journey planning and estimating correspondence delivery times across the empire.

Through enduring archaeological evidence and written documentation, researchers have reconstructed the appearance of this ancient road network.

A comprehensive new digital dataset and map published by researchers led by Tom Brughmans from Aarhus University in Denmark reveals nearly 300,000 kilometers of roads spanning an area approaching 4 million square kilometers.

The Roman road network circa 150 AD. Itiner-e, CC BY

The Itiner-e dataset was meticulously compiled using archaeological and historical records, topographic maps, and satellite imagery analysis.

This represents a substantial 59% increase from previous mappings that documented 188,555 kilometers of Roman roads, significantly expanding our knowledge of ancient infrastructure.

The Via Appia stands as one of the oldest and most significant Roman roads. LivioAndronico2013 / Wikimedia, CC BY

Of the 14,769 defined road sections in the dataset, approximately one-third are classified as long-distance main roads (including the renowned Via Appia connecting Rome to southern Italy). The remaining two-thirds consist of secondary roads, most without known names.

The researchers have been transparent regarding data reliability. Only 2.7% of mapped roads have precisely known locations, while 89.8% are less precisely documented, and 7.4% represent hypothesized routes based on available evidence.

Itiner-e improves upon previous efforts with enhanced coverage of roads in the Iberian Peninsula, Greece, and North Africa, while implementing crucial methodological refinements in route mapping.

Rather than depicting idealized straight lines, the researchers adapted previously proposed routes to conform to geographical realities, allowing mountain roads to follow practical, winding paths.

Itiner-e includes more realistic terrain-hugging road shapes than some earlier maps. Itiner-e, CC BY

Despite the considerable increase in Roman road data, this mapping doesn't incorporate all available information. Examining Rome's hinterland reveals careful attention to major and secondary roads but no mapping of smaller local networks uncovered through field surveys over the past century.

While Itiner-e excels at presenting the broader picture, it highlights the need for more detailed localized maps incorporating knowledge of specific cities' transport infrastructure.

Substantial published archaeological evidence remains to be integrated into digital platforms and maps for wider academic accessibility.

Fragment of a Roman milestone erected along the road Via Nova in Jordan. Adam Pažout / Itiner-e, CC BY

Itiner-e's map incorporates key elements from Stanford University's Orbis interface, calculating estimated travel times between points in the ancient world.

Road travel calculations assume humans walking (4km per hour), ox carts (2km per hour), pack animals (4.5km per hour), and horse couriers (6km per hour).

These calculations, while informative, exclude mule-drawn carriages, which constituted the primary form of passenger travel. Mules, with their superior strength and endurance compared to horses, became the preferred draft animals throughout the Roman empire.

Itiner-e provides a novel tool for investigating Roman transportation systems. Researchers can now correlate the map with known city locations to better understand how transport networks supported the lives of ancient inhabitants.

This opens new research avenues as well. With the road network defined, researchers might estimate the number of animals—mules, donkeys, oxen, and horses—required to maintain communication systems.

For instance, how many journeys were necessary to communicate an emperor's death (often occurring in a province rather than Rome) throughout the entire empire?

Some inscriptions reference specific dates for road section renewals due to bridge collapses and other damage. Itiner-e may facilitate investigation into the effects of such infrastructure failures on the broader road network.

These questions and many others await further exploration.

Ray Laurence, Professor of Ancient History, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.