A webpage created for Archaeology of Rome

by Casey Kraftick

Roman Roads

In slightly over 400 years, Roman legions built 53,568 miles of roads. Since one Roman mile equals 1,620 yards, this translates into about 50,000 standard miles. This mileage was spread over 34 countries through a network of 372 highways. Originally, these roads were financed by the land-owners through which these roads passed. Later, they were financed by private donations. Eventually, taxes were collected at city gates for new construction as well as maintenance of existing roadways.

Road construction was based primarily on the importance of the road and the material found in the vicinity. These roads were directionally straight, meaning they proceeded in a generally straight line with few curves. Considerable attention was paid to the subgrade, resulting in a high quality road system which required little maintenance.

A typical roadbed would be built by first removing the upper layers of soil until firm material was found. The resulting ditch was filled with four to six inches of sand covered over with about one foot of flat or squared stones laid in cement or bound in clay. This layer was known as the statument. Following this layer was the rudus, a ten inch thick bed of concrete made from small stones, gravel, crushed brick, or tile. Over the rudus was the nucleus, an eighteen inch layer of concrete which was firmer than the rudus. This layer was rolled out in successive layers until the desired thickness was obtained. Finally, the summa crusta, or top layer, was laid. This layer varied according the materials found nearby. In Italy, the summa crusta was silex shaped in irregular polygons from one to three feet in diameter. Roads in Britain were sometimes surfaced with stones of flint laid in cement. Less important roads, such as those found in Africa, were surfaced with gravel. Some roads were not even surfaced at all. Roads within city limits sometimes even had curbstones.

The main Roman roads were usually fifteen to sixteen feet wide with a depth of three to four feet. In the Alps, the roads narrowed to six feet. The road surface was generally crowned to allow water to run off of the surface. It was not uncommon for roadways to have gradients of ten to twelve percent. Sometimes slopes of as much as fifteen to twenty percent were used, not only in the mountains, but for bridge approaches as well.

This network of roads allowed the Romans to move rapidly over their domain. Horse relays were able to cover fifty Roman miles in twenty-four hours. Since there were no customs barriers at that time, travel was always open and free. Police guarded against highwaymen.

With this unprecedented mobility, it became necessary for travelers to not only know how far they had gone, but also made necessary the building of lodging along the way. The first objective was achieved by constructing milestones along the roadways. These markers were eight feet high, twenty inches in diameter, and weighed two tons. They gave the distance to all the principle cities in the region.

As for lodging, this was achieved as early as 2 BC An average of one stop every ten miles was constructed. These way stops were of three basic types. Mutationes were spaced about ten to twelve miles apart. They provided fresh horses for the emperor's messengers, similar to the Pony Express stations. Then there were mansiones, places where travelers could spend the night or procure supplies. They were located about thirty to forty miles apart. Finally, civitates were located at the junctions of major roads and in principle cities. The civitates were open to all who traveled and provided all the comforts of a modern Roman home.

Within this vast network of roadways, several roads are of particular interest. The first is the Via Appia, constructed in 312 BC, by Appius Claudius. This roadway is Rome's oldest road. Another interesting road is the Via Hadriana. This road led from Carthage to Thugga. After digging a ditch wider than the proposed road, heavy human operated rams were used to compact the soil. Nine inches of stone was added, and then topped with a thick course of gravel. This road when finished was eighteen feet wide. Along the road can still be seen the remains of seven large cities, ten dams and bridges, seven milestones, and three triumphal arches. One final route of interest is the Kazanpass along the Danube river. This roadway was carved out of the rocky cliffs. This roadway was only wide enough for one wagon due to the difficulty in removing the rock. The usual method of excavation was to pry out pieces of rock following natural fault lines. If this didn't work, the rock was heated and vinegar was poured over it. This reaction caused the rock to split open, facilitating the removal of the rock.