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The passage of carts over decades could cause ruts (like the one shown), particularly in high-traffic areas of Pompeii.

Romans in Pompeii Repaired the Roads with Molten Iron

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The buried city of Pompeii continues to provide many insights into Roman society , economy, and culture. The ash and pumice , that fell on Pompeii from Mount Vesuvius , froze the city in time. A recent study of its road system, however, has provided another fascinating insight. It appears that the resourceful Romans repaired roads with molten ore in the 1 st century AD.

A study of the roads that traverse the archaeological site was carried out by Eric Poehler of the University of Massachusetts Amherst, independent researcher Juliana van Roggen, and Benjamin Crowther of the University of Texas at Austin according to Archaeology. Org . They found that the narrow streets which are paved with stones became rutted and pot-holed over time. It seems that heavy carts and wagons cut deep ruts in the roads, over a number of years.

The poor state of repair of the roads would have made them very difficult to travel upon and even dangerous. A poor transportation system would have been bad for the local economy and would have disrupted daily life.

Deep ruts formed on Pompeii's paved streets as carts eroded the stones: ‘A’ shows an area of street with deep ruts; ‘B’ shows an area with repairs; section ‘C’ shows another deeply rutted section

Deep ruts formed on Pompeii's paved streets as carts eroded the stones: ‘A’ shows an area of street with deep ruts; ‘B’ shows an area with repairs; section ‘C’ shows another deeply rutted section. ( Eric Poehler / Fair Use)

The New Road Repair Technique

The researchers noted that there was a great deal of “iron droplets, spatters, and stains found on Pompeii’s streets” reports Archaeology. Org . They then concentrated on conducting a survey of the iron remains on the streets of Pompeii.

According to the American Journal of Archaeology , they found “434 instances of solid iron and iron staining among the paving stones.” It soon became apparent that the Pompeiians had used molten iron to repair the roads in their city, before the eruption of Vesuvius.

This was an exciting discovery because no-one had previously even suspected that the Romans used molten metal to repair their paved roads. The survey by the three experts proved for the first time that Romans used this ingenious road repair technique. The researchers believe that the use of molten iron was ideal for fixing the rutted roads in ancient Pompeii.

Iron remains found on Pompeii's streets: ‘A’ shows an iron droplet, ‘B’ shows iron splatter, and ‘D’ an iron stain.

Iron remains found on Pompeii's streets: ‘A’ shows an iron droplet, ‘B’ shows iron splatter, and ‘D’ an iron stain. ( Eric Poehler / Fair Use)

Live Science reports that, “complete repaving in stone, was a difficult and expensive endeavor that might block important through-routes in a city for months.” Then the roads would have to be repaired regularly because the heavy traffic on the roads would wear down the paving on the road every few years. So, the Romans came up with a clever way to deal with the problem and one that demonstrates their great engineering skills .

Example of Roman Ingenuity

The study found that they would heat iron and they would pour it into the holes and ruts in the road. Once the molten ore hardened, the roads could even be used by heavy carts. The experts also found evidence that pieces of pottery and ceramics were used as a filler to fill in the holes and ruts.

Live Science reports that “this method of repair was cheaper and faster than repaving a street, researchers found.” It would also have ensured that traffic disruption, caused by road repairs was kept to a minimum, something that was demanded by the citizens of Pompeii, just as it is demanded in modern cities.

The general appearance of such a metaled road in an existing street of Pompeii

The general appearance of such a metaled road in an existing street of Pompeii. (Roede / Public Domain )

It is something of a mystery as to how the Romans were able to apply liquified molten ore into the streets. They would have needed “to heat up iron or iron slag between 2,012 and 2,912 degrees Fahrenheit” reports Popular Mechanics .

Based on recreations of smelters, the experts believe that the Romans had the technology to produce the necessary high temperature. However, this method of repairing the roads often left unsightly splatters of iron on the streets based on the study’s findings. The researchers found that repairs using liquefied ore were being carried out just before the city’s destruction .

Public Slaves Did the Work

Roman Italy was a society that was built on slavery in the 1 ST Century AD. It seems likely that specially trained slaves would have been employed to melt the iron ore and were also responsible for pouring the heated metal into the potholes that developed in the streets. They would have had to carry the ore and pour it into the damaged stone paving.

This was a dangerous job, but slaves were plentiful and expendable. The road repairs could have been carried out by ‘ public slaves’ according to Live Science that were owned by the municipality of Pompeii.

Roman slaves built and performed repair on the roads

Roman slaves built and performed repair on the roads. ( johnwoodcock)

The team is continuing their study and they are at present conducting tests of the iron to determine its provenance.

This study is demonstrating the great practical skills of the Romans, which was one of the factors that allowed them to conquer and maintain such as vast empire. How prevalent this practice was, needs to be studied further. The research also shows that ancient Pompeii developed a system of road repair that was possibly more efficient than many modern municipalities.

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Top image: The passage of carts over decades could cause ruts (like the one shown), particularly in high-traffic areas of Pompeii. Source: Eric Poehler / Fair Use.

By Ed Whelan

Comments

I wonder if the three big stones across the road in the first photo are there to help people cross the road, for example in case of a heavy rain. If so, that would have been a serious obstacle to the horses pulling the carts and I wonder if there was room for more than one horse in between the ruts. I also wonder why there are no wear marks on the stones between the ruts from the horses drawing the carts, even in the case of horses not equipped with horseshoes and the cart wheels having iron rims.

Gary Moran's picture

They must have had a means of melting it very close to the repair site, and a conventional  furnace of that type would not be easy to transport. Perhaps trhey used brown gas as it is speculated in South America to melt the metal ‘keys’ used to join stones in walls and foundations. There are modern companies marketing generators that refine the gas from water.

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