The sentence "Jinsha water beats the clouds and cliffs are warm, and the Dadu Bridge crosses the iron rope and is cold" is a poem written by Chairman Mao during the Long March.
Including this sentence, the whole poem expresses the heroic joy of our party leading the Red Army to overcome many difficulties and obstacles, and the "Dadu Bridge" here refers to the Luding Bridge located on the Dadu River in Luding County, Ganzi, Sichuan, on the mainland.
Luding Bridge from ancient times to the present is to connect the Tibetan and Han traffic to play an indispensable role in the role, its earliest bridge history can be traced back to the Qing Dynasty Kangxi period, "Luding Bridge" is the emperor's imperial pen personally approved.
Looking at the Luding Bridge in detail, it is a suspended chain bridge erected on top of the turbulent water, and such a steep construction environment still needs to be carefully improved many times in modern times to ensure that nothing goes wrong before the construction can begin.
So, 300 years ago, when technology was not as developed as it is today, how did craftsmen build the Luding Bridge with 40 tons of iron chains in one year?
After many measurements, the material of the bridge was determined
As a world-renowned transportation construction, the whole process of the initial construction of Luding Bridge was not smooth sailing, but experienced many ups and downs.
In the beginning, when there was no bridge connecting the two sides of the Dadu River, the material exchanges between Tibet and Han were all carried out by ferries or ziplines.
However, the water potential of the Dadu River is not stable, casualties and material losses occur from time to time, and during the period when the river cannot be crossed, the fresh products stranded on both sides of the river are repeatedly rotted, resulting in great economic waste.
On the political and military fronts, inconvenient transportation also discourages the movement of troops, which in turn has a negative impact on centralized rule.
Based on this situation, at that time, when the Qing Dynasty ruled the world, the supreme ruler Kangxi Emperor ordered the construction of a bridge over the Dadu River to solve the problem of traffic congestion in the neighboring areas of Han and Tibet.
As soon as the imperial power of the feudal dynasty was supreme, the relevant departments of the imperial court began to send officials and craftsmen to promote the bridge repair project, and the first step was to conduct on-site inspections and then draw a feasible construction plan.
At first, before arriving at the local area, everyone had only heard about the harsh natural environment of the bridge repair site, but when they actually arrived at the local area and prepared to start a big job, they couldn't help but be dumbfounded, the reality is far more complicated and difficult than imagined.
It turned out that the water flow of the Dadu River was not only as turbulent as imagined, but also the river was 100 meters wide, so it was difficult to determine the type of material used to build the bridge first.
In order to withstand the impact of the rapid flow of the river, the craftsmen also had to consider how to transport it under the underdeveloped traffic conditions at that time, so the first consideration of the craftsmen was to take the material as close as possible.
The Dadu River is located in a remote mountainous area, with many stones and trees, so the craftsmen at that time first considered these two materials, after all, there were many successful cases of ancient stone bridges and wooden bridges on the mainland before the Qing Dynasty.
But on paper, it was never clear that it was going to be done, and when the craftsmen actually experimented with it, both materials were quickly rejected.
Because of the humid local environment, the soil by the Dadu River is very loose by the river water all the year round, and natural disasters such as mudslides occur frequently, the wooden bridge will collapse, and the weight of the stone bridge is difficult to be supported by the soil on both banks, and there is also a risk of collapse.
Fortunately, after many surveys and discussions among the craftsmen, and after rejecting several materials one after another, the final material for building the bridge was determined, that is, to build a suspended chain bridge.
The structure of the iron chain not only ensures durability and durability, but also reduces weight compared to the use of monolithic materials, which is the best of both worlds, but after overcoming the problem of bridge construction materials, the construction process of Luding Bridge is still not easy.
Overcoming difficulties, craftsmen have great wisdom
Soon after the bridge construction team decided to start construction, it ushered in new challenges, first because there was no iron ore in the Dadu River area, and there was no iron production in the local area, the person in charge of the bridge construction needed to go to the surrounding counties to forge the iron cables needed to build the bridge.
In addition to the hard work of traveling between the two places and the cumbersome transportation, the craftsmen encountered a technical problem, that is, how to hang the forged 40-ton iron chain on the Dadu River.
After all, standing on the bridge and looking down, the largest tributary of the Min River, a tributary of the Yangtze River, is always surging, and there is a risk of being swallowed up by the rushing river if you are not careful.
Based on the consideration of the soil foundation on both sides of the river, the craftsmen naturally could not complete the river operation at one time with such a large weight of iron chains, so they could only connect the two banks in batches, and if the ship valve was used to transport by the river, there was also a risk of being overturned by the torrent.
Inspired by the "rope crossing principle", the craftsmen tied thick bamboo ropes with multiple short bamboo tubes to the banks of the river, and the bamboo tubes were tied with iron chains, so that the people on the opposite bank could reach the preset position by gently pulling the operation.
In this way, not only the 40-ton iron chain was built on the Dadu River in an orderly manner, but also successfully completed the cross-river convection transportation, which not only saved time and effort, but also guaranteed the safety of the craftsmen's work.
In this regard, there is also a folk story, according to the locals, the Kada Temple on the west side of the Luding Bridge was built to commemorate the Tibetan hero Kada who made great contributions to the construction of the bridge.
According to legend, in the face of the iron chain that everyone could not hang in the air after racking their brains, Kada, who was born with divine power, grabbed an iron chain in each of his armpits and took it to the opposite shore by boat.
He went back and forth several times until all the chains were gone, and Kada died of exhaustion.
Therefore, this hero who contributed to the success of the bridge was commemorated by the locals by building a temple, but this is only a form of people's wishes in the face of the difficult reality, and the strange power and chaos in reality are far less than the spirit and ingenuity of the craftsmen.
Of course, it is not enough for a bridge to be composed of suspended iron chains, and in order to put the bridge into a wide range of daily applications after the completion of the bridge, in addition to a strong bridge head on each side, there must also be a bridge deck that can be steadily stepped on by pedestrians.
Therefore, the craftsmen built the bridge head with large stones on both sides of the river, and in order to ensure its stability, the craftsmen chose to dig deep down the bridge head at both ends and cast it with pig iron to connect and fix.
Since then, the stability of the bridge has been ensured, and the craftsmen have laid wooden planks on the underside of the original cable suspension bridge to create a flat and solid bridge deck.
The surface of the wooden bridge and the iron chains on the lower layer as support and connect with each other, and the iron chains on the left and right sides are interlocked, forming this cross-century bridge that has survived the vicissitudes of the times.
Looking back at Luding Bridge from a modern point of view, the craftsmen of 300 years ago were based on the level of science and technology at that time.
It is a very difficult project to be ordered to build the bridge, which consumes countless manpower and material resources, and more importantly, it is more important to overcome and solve the problems of iron cable supply, iron cable crossing and heavyweight iron cable suspension on the river and fixing.
This was a huge challenge for the craftsmen, and it was also an opportunity to show the traditional craftsmanship and wisdom of the mainland to overcome difficulties, and finally everyone brainstormed a solution and successfully built the Luding Bridge.
The completion of the bridge not only benefited the people on both sides of the river at that time, but also strengthened the centralized control over the locality, consolidated the rule of long-term peace and stability at that time, and left a priceless treasure of great economic, cultural, political and other multiple meanings for future generations, which is the concentrated projection of the wisdom of the traditional working people of our Chinese nation.
Reference: China National Knowledge Network "How the Luding Bridge Was Built" Zhang Yan