While the Ancient Greeks are often lauded for their contributions to many fields such as poetry, philosophy, and mathematics (to name a few), the incredible engineering feats of the Ancient Romans were instrumental in their infrastructural and organizational efforts, and these ingenuities are employed by engineers even today. You may be surprised to find that some of the items below have roots in Roman engineering!
Concrete
Although it is unclear when Roman concrete was initially developed, its use was widespread by about 150 BC. Roman concrete, also called opus caementicium, is based on a hydraulic-setting cement. Due to the inclusion of pozzolanic ash, it is incredibly durable. The setting of pozzolanic cement has much in common with the setting of its modern counterpart, Portland cement, namely in its high silica composition. Like any concrete, opus caementicium consists of an aggregate and hydraulic mortar. The aggregate can vary, and Roman engineers utilized pieces of rock, ceramic tile, and brick rubble from the remains of previously demolished buildings.
Roman concrete was developed further as its uses grew, leading to what is called the concrete revolution, which saw the development of civil engineering structures, public buildings, and military facilities that included amphitheaters, aqueducts, baths, bridges, circuses, dams, roads, and temples.
Roads
Certainly, one of the most impressive engineering feats of the Ancient Romans is their sprawling road system. Much of Rome’s infrastructure and development would not have been possible without the aid of its roads, of which there were more than 53,000 miles by 200 A.D.
Roman roads were typically straight, and if faced with obstacles during construction, the Romans would either engineer a way through the obstacle or build the roads over it. This resulted in very steep roads that would not be suitable for modern traffic. Eventually, some alternatives would be built to roads that were difficult to manage.
The most durable of the Roman roads, viae munitae, were constructed through several steps. The soil would be loosened, and the ground would be dug out and then tamped down to a leveled, compact layer. Large stones would be packed as tightly as possible into the earth base, followed by smaller stones, broken concrete, somewhat crushed rock, or even sand, again packed and smoothed. Next, a layer of gravel would be added, packed, and leveled. Near large cities, paving stones may be used as a top layer instead, which could be made of flint, lava rock, or marble. The end product is thought to have been smooth and would facilitate relatively peaceful travel in carts. The center of the roads would generally be higher than the sides and flanked by drainage ditches as well.
Sewers
Initially, sewage systems were developed to drain marshes and storm runoff. Over time, these systems would be expanded further with more waterways. The sewage system as a concept did not reach popular usage until the Cloaca Maxima, used in Ancient Rome to carry human waste to the nearby Tiber river. Significantly, the Cloaca Maxima was eventually covered, reducing disease and unpleasant sights and smells. And because of Roman aqueducts, it was not necessary to rely on the Tiber for water supply.
Around 100 A.D., Romans began constructing direct connections from the sewage systems to citizens’ homes. Although this mostly benefited only the wealthy, it was a step that solidified the importance of the sewage system.
Heated Floors
Heating had proved to be a very difficult task for the ancient world. Fire was difficult and dangerous to control, and smoke could be annoying and possibly deadly. Roman engineers created a brilliant solution—the hypocaust. Hypocausts were not typically used for housing because of high costs, and thus were usually delegated for large villas and public baths.
A furnace would sit below a room, keeping the fire and smoke at a safe distance from the primary structure. Pillars were used to raise the ceiling of the hypocaust and support a layer of tiles, followed by a layer of concrete, and finally the floor tiles of the rooms above. Heat and smoke from the furnace would circulate through the enclosed area and then move up through clay or tile flues, called caliducts, that were set in the walls of the rooms above to outlets in the roof, thereby heating the floors and walls.
The Segmental Arch
Although arches had existed for some 2,000 years before Romans invented the segmental arch, they were faced with one large restriction: they needed to be one continuous semicircle that bridged a single gap. Roman engineers realized that arches in bridges could be segmented, thereby allowing more freedom in the passage of water and more durability for the bridge’s supports. Additionally, the potential distance that could be spanned by a single bridge was drastically increased by the introduction of the segmental arch.
Aqueducts
People tend to be most familiar with the Roman aqueduct, and rightly so. Water sourcing and distribution was a serious problem that faced large ancient cities. Although Rome sat on the Tiber, it became more and more polluted by the sewage system that Roman engineers had devised. The solution was the extremely large and complex aqueduct system. The first aqueduct was built in 312 BC and was used to supply water to a fountain in the city’s cattle market. By 200 AD, Rome had 11 aqueducts spanning over 250 miles in length that sustained a population of over one million. Cities and towns across the Roman Empire emulated the aqueduct system, and it became both a necessity and a luxury.
Aqueducts carried water using only gravity along a slight downward gradient within a stone, brick, or concrete conduit. The conduits most often ran underground and followed the terrain of the land. If there were peaks that obstructed the gradient, they were either circumvented or tunneled through. The conduits were carried by bridges if valleys obstructed the flow of the terrain, or funneled into a high-pressure lead, ceramic, or stone pipe and siphoned across. Aqueducts were regulated by law and anyone who wished to build one had to submit their proposal to the proper civil authorities. Before construction could begin, Roman engineers would survey the land over which the aqueduct would run to ensure the water would flow at an acceptable gradient for the entire distance.
Do you have any thoughts on the engineering feats accomplished by the Ancient Romans? Feel free to share your comments with us below.
Over the years I have mentioned these items to colleague’s pointing out that we are not such hot stuff and that the Romans pioneered many things. Add to this list the Romans had their own version of the high rise apartment buildings they called insulae. They also had their own version of tremie concrete. A large part of the road construction and maintenance was done by the legions for obvious reasons but commerce also benefited greatly from these military highways. Roman legates found that keeping the men working on roads between campaigns kept idle hands busy.