The first and simplest vehicle found in Rome was the plaustrum. It was little more than a flat board carried on four wheels. The wheels were rigidly attached to the axle and the axle itself was also made to fit the cart. This made wagon steering a cumbersome affair and meant very low efficiency. These problems and the fact that no flexible cart had been invented to tie the animals up in front, only the Celts had invented a balanced harness to pull the load overland, which was costly and time consuming.
The most impressive skill in Roman transportation was the so-called cursus publicus (something like ‘public hippodrome’). This postal service was started by state couriers bringing information and instructions to the far reaches of the empire. This relatively quickly turned into the organization of postal proceedings that connected the various provinces with each other. These were not really public postal services, as they were intended for people in the employ of the emperor and for the rich and powerful.
The cursus publicus was strictly regulated as to the size and capacity of its vehicles. It also specified precisely who was allowed to drive them, for what purpose, and who was responsible for their upkeep. Due to the high cost of building and maintaining the roads, transportation was administered according to strict stipulations, and great care was taken that a relatively light maximum weight was allowed for the different modes of transportation.
When the Roman empire lost its vitality, the cursus publicus became a victim of nepotism and misuse. With the disappearance of the central Roman power, the excellent qualities of the system disappeared. Only in modern times would the cursus publicus be equalized.
In general, transportation was carried out according to ancient customs. Sailing ships were given a smooth skin, instead of rivets, and a fully developed keel with bow and stern. The ancient Greeks used a square or oblong sail to catch the wind, and in the event of a headwind, they employed one or two rows of rowers to advance. The Greeks were the first, as far as we know, to build a special type of warship with a ram at the front. They also had cargo ships without oarsmen and these, of course, were totally dependent on the wind. These developments were completed by the time of classical Greece. The Romans adopted both forms without making any changes.
The Romans devoted much more attention to their roads than to sea transportation. They put together a remarkable network with carefully planned paths, both in terms of position and construction. The road network stretched throughout the length and breadth of all the provinces of the empire. Along these roads marched legions to wherever there was a crisis. The roads also served for the development of trade, but their main function was always the maintenance of imperial rule.
At the height of Roman power, trade was connected by land with the cultures of Europe, North Africa, Asia Minor, and even China and India. But the transportation system depended on the Roman, Chinese and Mauritanian empires. When these great powers collapsed, the trade routes became invasion routes for hostile foreign armies. Almost everywhere, road networks deteriorated over centuries. The transport of merchandise was replaced by troupes of beasts of burden that could travel those old roads and that were sufficient to transport the smallest flow of merchandise. It would last until the 12th century before the situation improved.