There is a considerable amount of road building, repairing and widening happening in North Carolina, and I am always fascinated by the way these roads come together in a way that is hard to imagine when the projects are begun. Our roads are built to last and be a safe way for us to get around.
I had assumed that the current state of the art of road building had just developed in the last 100 years, but recently I was listening to a book, The Decline and Fall of the Roman Empire, Edward Gibbon, 1776 (yup) which described the vast network of roads the Romans built throughout Europe, England, and further. What caught my attention was not only the amount of roads they built, but the quality of design and construction that allows us to see them even today in remarkably good condition.
The Roman road network is estimated to have been 53,000 miles of major roads and nearly 200,000 miles of secondary roads. According to the North Carolina Department of Transportation there are nearly 15,000 miles of primary highways and 65,000 miles of secondary roads in North Carolina, and the Federal Highway Administration indicates a total of 227,544 total North Carolina lane miles. No matter how you slice it, the Romans were prolific road builders.
The typical Roman road section is shown on the right. It consists of four layers, with two sub-stratum of squared stones and rubble base, followed by a concrete core and finally a pavement of stone slabs. As shown in the photo above, the roads were built with a convex arch to provide drainage into the adjacent ditches. Concrete was made with a cement of volcanic earth mixed with lime and water. This substance was a Roman breakthrough that allowed for many types of construction including construction beneath water. The Romans appear to have been knowledgeable of the properties of rocks and stones appropriate to their needs, and their craftsmanship was such that many of the pavements needed no cement to hold them as they were cut so precisely.
The well known phrase ‘all roads lead to Rome’ was originally ‘all roads lead from Rome’, and the image to the left shows why. The Roman Empire grew to a size unprecedented in human history, and roads facilitated that growth by allowing the transportation of troops, commerce and lines of communication. Perhaps the roads were also the downfall of the Empire in its latter years, as it also allowed ease of access for invaders from the north. Nonetheless, the roads of the Roman Empire live on and are an ongoing demonstration of their skills.
The Roman bridges, aqueducts and other stone construction are a whole other subject well worthy of discussion. Maybe a future newsletter…