Possessing an effective communications system was without doubt one of the main concerns of all Chinese emperors. The first Chinese empire was based on a well-organized army and tight control of the population. However, the measures taken as the basis of the empire included the unification and standardization of the systems of writing, coinage, weights and measures, and the length of cart axles. The first Qin emperor, famous for his mausoleum and his amazing terracotta army, had been the victor of the two-century long war between the states that controlled the different Chinese territories. Because the roads in each of those warring states had been adapted to a different set of cart axles, communications between the differing territories were difficult, and standardizing the axle dimensions therefore had to be prioritized.
The Qin made a huge effort to create an efficient system of roads, which crossed their country from north to south and east to west to link up the capital to the provinces. The emperor controlled a vast territory which included valleys, plateaus and mountainous regions, and all of them had to be absorbed by and articulated in the Qin administrative system. Significantly, the brief Qin empire (221-207 BC) made a huge contribution to the development of engineering in China. Their irrigation and communication infrastructure works are doubtless the most remarkable. Qin power was partly based on ambitious roads through mountainous regions, which relied on the ability of Chinese engineers to build bridges on difficult terrains. As in the contemporary Roman Empire, bridges were very soon made of stone and had both structural and aesthetic purposes.
After the fall of the Qin, all Chinese empires inherited the need to maintain and expand communication infrastructures. Given that the historical territories of China were irrigated by some of Asia’s most powerful rivers, and that vast regions had been shaped and economically articulated through human-made canals, building, maintaining and renewing bridges became a core aspect for those infrastructures.
Chinese engineers developed several types of bridge. The simplest bridges that can be found in ancient China are beam bridges, which could reach a maximum span of about 20 meters. The construction technique for this kind of bridge improved over the centuries: in the Song dynasty (960-1279), serialized stone beam bridges in Fujian province were (and some still are) incredibly long, stretching up to 1 kilometer and more. Another development in bridge design was the use of a cantilever beam - a beam that is firmly anchored at one end while the other end protrudes horizontally into the gap. This kind of bridge, less frequent, was soon used in China but its origin was probably the Tibetan plateau and the Himalayan region.
Arch bridges –bridges with abutments and arch-shaped- have probably been the most widely used bridges in China and worldwide. In ancient China, stone arch bridges reached spans of more than 50 meters. Finally, we must also mention suspension bridges. In suspension bridges, the support comes from above, originally by ropes, hanging from two braces and looping down through a curve known as catenary. At first, in their most primitive designs, pedestrians and animals followed the curve of the bridge, but very soon flat-platform suspension bridges were created. Suspension bridges were built in both Europe and Asia, and even in the Americas, but China was the first place where the transition from ropes to iron chains was made.
Several historians consider that the first mention of an iron-chain suspension bridge appeared in a text written in the 15th century, which describes how one of those bridges was repaired. This written account testifies that this type of bridge existed in China before anywhere else. Indeed, according to other scholars, Chinese engineers actually began to design iron-chain bridges far earlier, probably during the Sui dynasty (581-618) or not much later, although no clear textual evidence of this remains. In any event, this once again makes China one of the most preeminent agents in the history of engineering.
Universitat Oberta de Catalunya