Comprehension: Building Roads

The economic progress of a developed or developing country depends, to a large extent, on the greatest possible freedom of movement of food, raw materials, and manufactured goods. From this, it is clear that an efficient network of roads is economically essential. In the modern world, this is a major consideration in planned road building.

                   The earliest roads, however, served a different purpose. The Persians, for instance, in early times built long-distance highways. But their main purpose in doing so was to facilitate the rapid movement of troops across the country. We may reasonably draw the conclusion that the existence of good roads also facilitated trade both within Persia and with other countries.

                   Also in ancient times the Romans, needing roads to defend their huge empire, built excellent roads along which armies could be moved swiftly from province to province. Unfortunately, an army with all its baggage and equipment quickly wears out all but the best roads. Yet many Roman roads still survive. Consequently, we may conclude that Roman roads were of very high quality. How were they made? Usually, a Roman road consisted of a foundation of large stone blocks covered by a layer of smaller broken stones, over which was put a layer of sand. The surface was made from big basalt blocks or from gravel set in lime mortar. From these facts, we see that the building of a Roman road entailed a great deal of work.

                   The Romans had none of our modern road-building machinery and all the work had to be done by manual labour. Moreover, some roads had to be built from supplies of stone, basalt, or lime; it follows, therefore, that materials for road building must, in some cases, have been transported over long distances. In some regions where there was heavy rainfall, road surfaces were given a good chamber (i.e. were curved), so that the water drained away quickly. From all this, it is evident that much careful planning went into the building of a Roman road.

                   The Industrial Revolution began in Britain in the 18th Century. In light of this, we are not surprised that the modern age of road-building began late in the same country. Despite the development, since then, of many new road-making techniques, the foundation and the surface are still considered to be separate parts of any road, as they were in Roman times. From this, we may assume that the basic concept of Roman road-building was sound.

                   In any ordinary modern road, the foundations are made up of small stones or hardcore (large stones, old concrete, broken brick or similar debris), or large concrete slabs. In some places, water may rise through the foundations and damage the surface. To prevent this, a layer of ash is usually spread on top of the foundations and then compressed by a road roller. These roads are usually surfaced with tar macadam (broken stone coated with tar).

                   Modern highways, which carry a great deal of heavy traffic, are given concrete foundations usually with a steel mesh embedded in them to act as a reinforcement and to resist the stress of the traffic. Large sheets of waterproof paper are spread over the foundations to prevent water from rising. A further layer of concrete is used for the surface, and when that has hardened, a top layer of asphalt or tar macadam may be applied. All these processes are carried out with the aid of powerful and sophisticated machinery.

                   Given these facts, we might well come to the conclusion that modern highways will last longer than Roman roads have done. Is that conclusion justified? Only time will tell.

(NOSEC Book Four, pp. 120-121)