Roman roads, like major roads today, were built for communication, transport of goods, and movement of armies. The distinction of Roman roads is that they were the first roads forming a network connecting much of Europe and the Middle East, and they were also the first in Europe to be constructed with a base layer covered with paving stones, much as roads are built today. Not all their roads, however, were the same quality. Important and heavily used, long-distance roads were built for durability and many have endured to the present.
Roman builders used whatever materials were at hand to construct their roads, but their design always employed multiple layers. Crews began by digging shallow, three-foot deep trenches and erecting small retaining walls along either side of the proposed route. The bottom section of the road was usually made of leveled earth and mortar or sand topped with small stones. This was followed by foundation layers of crushed rocks or gravel cemented with lime mortar. Finally, the surface layer was constructed using neatly arranged blocks made from gravel, pebbles, iron ore, cut stones, or hardened volcanic lava. Roads were built with a crown and adjacent ditches to ensure easy water drainage, and in some rainy regions they were even positioned on raised berms to prevent flooding. The main roads were built 13.8 feet wide to accommodate two vehicles passing.
On the other hand, minor roads might be merely a dirt or gravel track connecting minor towns to major roads. This certainly sounds the same as road systems in use today. After a major road was built, Roman soldiers patrolled them to guard against thieves and to collect tolls. The illustration above shows a drawing of a major road under construction.
As with all their construction, the Romans were precise about their road-building. Roman surveyors used a groma, a set of wooden pieces in the shape of a cross that had lead weights on the ends. Lining up the weight hanging off one piece of wood with the piece hanging off the one in front guaranteed a straight line; from that workers could put wooden posts in the ground and then extend the road along the line. The Romans usually preferred to build roads in a straight line regardless of terrain. They drained or filled in marshy areas, or cleared a path through forests. Occasionally they made short deviations around rocky hills, but sometimes they excavated solid rock to maintain a straight line. During road construction the Romans added milestones one thousand paces apart (one Roman mile, 0.92 statute miles).
Another little known use of the roads was for tourism; many Roman citizens simply had an urge to visit parts of their far-flung empire and the roads made this possible. Romans were especially interested in visiting sites associated with their Gods and myths. The Romans also had a postal system and mail wagons using the roads to distribute mail throughout the empire in a relay system similar to the U.S. Pony Express. The constant traffic of Roman chariots, carts, and wagons created ruts in the stone surface of the roads that were carefully used and maintained because the ruts kept the wheels moving in straight lines, avoiding tipping over. In all, the Romans built more than 250,000 miles of roads that formed a network over their empire. This extensive network was a key element for their control of Western Europe and the Middle East.
As Romans came under increasing attack by various tribes of people over Europe, they eventually withdrew to the confines of Rome which finally fell around 400 A.D. The Roman road construction left a lasting impression in two ways. First is the continued use of some Roman routes, and even today many modern roads follow the routes of the original Roman roads with minor variation. The second lasting effect is an interesting story that concerns the width of the axles on Roman wagons and chariots.
You may have wondered (though probably not) why the standard width of today’s railroad track is 4 feet, 8.5 inches (4.708 ft). One answer, which is probably only partially true, is a matter of getting the horse before the cart…literally. The story says that the width of a horse’s rear first determined the axle width of a cart. If the axle is wider it increases the work for the horse and makes turning more difficult.
After the Romans left their territories in northern Europe many roads fell into disuse, but some continued to be used by the local people who built their carts to fit into the ruts left by Roman chariots and wagons.
By the seventeenth century English stagecoaches began to use the old Roman roads and their axle width was also designed to conform to the ruts. The date of the first use of stagecoaches as a means of public transport is not definitely known, but the first mention came as early as the thirteenth century, and they probably existed for some time before that.
In 1649 Edward Chamberlayne described his impression of stagecoach travel in his writings titled, Angliæ Notitia: Or the Present State of England.
Besides the excellent arrangement of conveying men
and letters on horseback, there is of late such an
admirable commodiousness, both for men and women,
to travel from London to the principal towns in the country,
that the like hath not been known in the world, and that
is by stage-coaches, wherein any one may be transported
to any place, sheltered from foul weather and foul ways;
free from endangering one's health and by the hard jogging
or over-violent motion; and this not only at a low price (about
a shilling for every five miles), but with such velocity and
speed in one hour, as that the posts in some foreign
countries make in a day.
(NOTE: One shilling in 1649 would be approximately twenty-five U.S. cents today.)
When English steam railroads first began in the early nineteenth century, the builders saw no reason to design a new and different vehicle for passengers. They simply adapted the stagecoach for use on rails. The conveyance pulled by real horses would now be pulled by an “iron horse” on rails. According to this premise, the axle width of the stage coaches determined the gauge of the railroad tracks. As the British developed their empire during the nineteenth century they built railroads of the same gauge in every country they occupied.
There is no certain proof that a linear connection actually exists between the width of Roman carts, stagecoaches, and the gauge of railroads. Perhaps it is simply a strong coincidence.
Another story is related to rail gauges, rockets, and horses’ rears. The big rocket boosters attached to the side of a space shuttle are built by Thiokol at their plant in northern Utah. These boosters had to ship by rail from the Utah factory across the Rocky Mountains to a launch site in Florida. En route they had to pass through tunnels that were just slightly wider than the train cars, and this width put a constraint on the design size of the rocket boosters. One could suggest, therefore, that the dimensions of modern space vehicles and the rail system were both influenced 2,000 years ago by the width of horses’ rumps. The truth of this connection is also uncertain but it makes a plausible story.
At the beginning of nineteenth century railroad building in the United States there was some variation in rail gauge. In the South particularly, the Confederacy built railroads of three different gauges. Historian James McPherson pointed out that this lack of standardization created an inefficiency that slowed distribution of goods and contributed to the defeat of the Confederacy. After the Civil War railroad tracks in the South were rebuilt to create a national uniformity of gauge. The important outcome, regardless of rail gauge, is a present day world network of railroad tracks, using the original British stagecoach axle gauge of 4 feet 8 1/2 inches.
Appian Way. https://en.wikipedia.org/wiki/Appian_Way
David Mikkelson. https://www.snopes.com/fact-check/railroad-gauge-chariots/
Roman Roads. https://en.wikipedia.org/wiki/Roman_roads
Roman Roads. http://www.socialstudiesforkids.com/articles/
Roman Roads. https://www.ancient.eu/article/758/roman-roads/