So far, no bridge on the Amazon River has dared to cross it. Why?

Because the Amazon River is located in the world's largest rainforest, it is the largest river in the world, with a wide river surface and fierce water flow, which is the second longest in the world, but so far no river has crossed the main road of the Amazon River.

The flow of the Amazon River is inseparable from the Amazon rainforest, which is the most dense forest resource in the world and is rich in plant resources. Trees as tall as the Amazon River keep growing and absorbing sunlight, and the highest can reach tens of meters. There are shrubs under the tree, which don't like light and prefer dark environment. There are also some herbs around the bushes that don't like light. Because of the huge variety and quantity of plants, transpiration is quite obvious.

Transpiration is that after the leaves of trees are heated, in order to prevent the leaves from being burned by the sun, trees transport more water to the stomata, and keep the temperature of the leaves through evaporation of water, which is also the basis for plants to absorb water and minerals from the soil. Transpiration will transport a lot of water vapor to the sky above the rainforest, so the rainforest is rainy and the weather changes dramatically. The largest raindrop recorded by scientists is above the Amazon rainforest, with a diameter of 0.8cm- 1. 1 cm.

These factors make the rain in the rainforest very violent, and with the influence of the earth monsoon, the tropical Amazon rainforest is divided into rainy season and dry season. The rainfall in rainy season is more fierce, at least 2000 mm per year, and even more than 10920 mm in some areas. Thunderstorms are also frequent, so floods often break out in the Amazon basin, and the width and depth of rivers vary greatly. The impact of water flow has also eroded a lot of surface materials, making it a depression compared with other parts of the mainland. Similarly, the Congo River in Africa is also located in the basin, so the water in flood season can be accumulated in a certain period of time, and the change of river width will be very significant.

Although there is a vast alluvial plain along the river, the river is often diverted by floods, and the changes in the depth of the river often flood farmland. Therefore, the houses of residents along the river are mostly similar to the diaojiao building of a minority in China. They live in high-rise buildings in flood season, and the river may flow from below. These characteristics of the Amazon basin make it difficult to develop agriculture in the alluvial area of the Amazon River, and it is also difficult to build bridges because of the frequent diversion of rivers. The river course is also quite complex, with uneven terrain and many rapids, and the construction of bridges also needs a large-scale transformation of the surrounding environment.

There is another very important factor. The rainforest area is rich in biological resources, but it is not suitable for human habitation as a whole. There are often some tribes, large and small, in the Amazon basin, which makes urban construction difficult. Most large cities are located in the southern plains of Brazil. Most cities along the Amazon River are port cities, such as Macapa near the estuary, with a population of only 400,000, while Brazil's national population exceeds 200 million. The population is mainly concentrated in the Brazilian Plateau in southern Brazil and the coastal areas in the southeast. The transportation demand can be met by water transportation in the Amazon River basin, while the cities in the south have less demand for the cross the amazon rainforest and sailing northward through the Amazon River.

The development of water transportation in Amazon River may also increase the difficulty of bridge construction, because the water level can soar by 20 to 30 meters in flood season, so the height of the bridge needs to be quite high. Many factors make the Amazon River lack of bridges, and only some tributaries have bridges, so the communication places are limited. Unlike our cross-sea bridge, which can link a large-scale economic belt, Brazil's economic and technological conditions do not need a large-scale bridge for the time being, and building in the rainforest may also destroy the rainforest ecology. In short, the Amazon River is really hard to tame.