After the fall of the Western Roman Empire, the ancient infrastructure deteriorated without repair and maintenance, and the
mainstream of world inventions was shifted to China. This is where a system of roads successfully used by the state postal service had been in operation since the last centuries of the previous age. The Chinese (likewise the Romans) built strategic roads branching in different directions from the capital city on a large scale. They independently developed their skills building different types of bridges – from wooden and stone, through frame and finally iron ones.
The oldest bridge in this region of the world is considered to be Zhaozhou Bridge (Anji) in Zhao Xian, built in the 7th century. It was erected as a 7.3 m tall sectional arch with a span consisting of 28 narrow arches made from limestone aggregate.
In addition, the Chinese materially improved horse-drawn carts when a horse-collar transferring the load onto the horse’s shoulders was invented in the 5th century CE. Through Iran, it reached Europe around the year 800, acquiring its final, modern shape in the 12th century.
In the 14th and 15th century the Incas created a developed system of roads in Peru. It was quite surprising since they did not know anything about wheels and the only pack animals they used were llamas. The roads were used for sending orders in a relay race system through messengers who had to be good runners. As reported by the conquistadors, the messengers could run for more than 200 km a day, so four times faster than the horseback service organized by the Spanish conquerors. An impressive complement of the Incan road network was suspension bridges. The largest of them spanned 45 m. They were made from twisted plant fibres and wooden elements that were replaced every year because they were not very durable.
Although Europe was a leader in science and technology, for many centuries it did not develop its transport routes at all. On the other hand, the construction of bridges developed intensively as they were considered an act of mercy. A new trend – pointed arches – appeared at that time. Thus, the piers could be narrower, which along with the increasing span, added clearance under the bridge.
One of the oldest medieval bridges is the bridge over the Danube in Regensburg. It was erected in 1135-1146 as a 336 m long and 8
m wide structure. This stone monument was modelled on Roman standards with strong longitudinal slopes and larger clearance under the central spans to facilitate the passage of water. To increase flooding security, a relief canal bypassing the bridge was built.
Another achievement of medieval bridge construction is the bridge on the Rhone in Avignon. The bridge had 22 spans totalling a length of 900 m. Apart from its size it was distinguished by an excellent structure – the arches were elliptical and narrowed at the top. Thanks to this the supports could be narrower and the arches taller. The bridge was not built straight across the river. Its bending towards the western bank was protection against the thrust of water.
Medieval Florence, in order to become the capital trading city, had to ensure a transport connection across the temperamental Arno river. In 1345, the Ponte Vecchio – a stone bridge with symmetrical arches was put into use. Its wide piers supported flat vaults with the span and arch ‘rise’ from 3.9 to 4.4 m, while the extensive deck carried two rows of shops built from brick. This structure is one of the few structures with a built-up deck that have survived unchanged to contemporary times.
Similarly, the authorities in Prague erected bridges taking care for the economic development of the country. The first bridge was built of wood, and then of stone, in honour of Queen Judith. The construction of another bridge started in 1357. The Charles Bridge (516 m long and 10 m wide) can still be admired for its monumentality and combination of different styles. Apart from semicircular Roman-like arches, it features supports typical of medieval times and a gallery of Baroque sculptures on the railings.