The Amazon River is the second longest river in the world and one of the most important waterways on the planet. It has more fresh water by volume than any other river, is home to the world’s largest river dolphin species, and hosts 100 species of electric fish and up to 60 species of piranhas.
However, despite its many and varied qualities, there is something that cannot be found in Amazon River: bridges.
Given the flow of the Amazon through three countries (Peru, Colombia and Brazil) and more than 30 million people live in the river basin, According to the World Wildlife Fund (Opens in a new tab)It seems somewhat unlikely that there are no bridges spanning the river. So why this case? Are there fundamental difficulties in constructing such structures in a rainforest that contains trade-offs, extensive wetlands, and deep, thick shrubs? Are there financial barriers? Or is it simply not worth it?
When compared to some of the other more famous rivers in the world, the Amazon’s lack of bridge crossings is odd. There are about nine bridges spanning the Nile in Cairo alone. more than 100 (Opens in a new tab) Bridges have been completed in the past 30 years across the Yangtze River, the main river in Asia; While the Danube River in Europe is one-third the length of the Amazon 133 bridge crossings (Opens in a new tab).
So what’s the deal with Amazon?
“There is not a sufficiently urgent need for a bridge across the Amazon,” said Walter Kaufmann, President of Structural. engineering (Concrete Structures and Bridge Design) at the Swiss Federal Institute of Technology (ETH) Zurich, told Live Science in an email.
The Amazon, 4,300 miles (6,920 kilometers) long, meanders through sparsely populated areas, meaning there are very few major roads with which any bridge can connect. And in the cities and towns bordering the river, boats and ferries are a well-established means of moving goods and people from bank to bank, which means there is no real need to build bridges, other than to make trips a little faster.
“There are, of course, technical and logistical difficulties,” Kaufman noted.
According to Kaufman, far from being an ideal location for bridge builders, the Amazon region contains a host of natural obstacles that engineers and construction workers must conquer.
For example, its vast swamps and loose soil necessitate “very long access bridges [a multi-span bridge crossing extended lower areas] and very deep foundations, “and this would require huge financial investments,” Kaufman said. In addition, the changing attitudes of the riverbed across the river seasons, with “obvious differences” in water depth, that would make construction “extremely demanding”. This is due in part to the river’s rising and falling water levels throughout the year, and the erosion of soft sediment on the banks of the rivers and changing seasonally, according to the report. Amazon Waters initiative (Opens in a new tab).
Kaufman noted that while these particular issues are not limited to the Amazon, they are “particularly serious” there.
“The environment in the Amazon is certainly among the most difficult [in the world]Kaufman said. “Bridges across the strait are also a challenge if the water depth is deep, but at least you know that construction is possible with buoys, for example.”
Rafts, or floating structures, are not a solution that will work in most parts of the Amazon, Kaufman said, because the river is highly affected by seasonal changes, which adds an extra layer of complexity. For example, during the dry season – between June and November – the Amazon River averages between 2 and 6 miles (3.2 and 9.7 km) wide, while in the rainy season – from December to April – the river can be up to 30 miles wide (48 km), the water level can be 50 feet (15 m) higher than during the dry season, According to Britannica (Opens in a new tab).
“This challenge will be unique,” Kaufman said.
So, in addition to not having an immediate need for a bridge across the Amazon, the processes involved in building one would be significant.
A bridge too far?
It should be noted that although there are no bridges crossing the Amazon, there is one that crosses the Negro River, its main tributary. The bridge is called the Ponte Rio Negro, completed in 2011, and connects Manaus and Errandoba, and is so far the only major bridge crossing any tributary of the Amazon.
But, while there are no concrete plans to build a bridge over the Amazon, “that doesn’t mean it won’t happen,” Philip Firenside, an American biologist, scientist and conservation activist who has spent most of his career in Brazil, told Live Science. .
In 2019, Jair Bolsonaro, President of Brazil, He announced that he wanted a bridge (Opens in a new tab) across the Amazon to be built as part of his “Rio Branco Project”, but no progress has been made so far. “It would be very costly compared to the economic benefits that it would bring,” Firenside noted.
Upon completion of the Ponte Rio Negro Bridge, interim plans were drawn for a bridge across the upper Amazon – known as the Solimões River – in Manacapuru Municipality, which would connect the BR-319 to Manaus and eliminate the need for a ferry crossing.
“BR-319 is a high political priority, but it has no economic justification,” Firenside said. “It is cheaper to transport products from factories in the Manaus Free Trade Zone to São Paulo by water.”
Additionally, as noted in the 2020 commentary, Fearnside wrote for the environmental news site mongabay (Opens in a new tab) With regard to the proposed development of the BR-319, the construction of such a bridge “would give deforestation It has access to nearly half of what remains of the country’s Amazon rainforest, and is thus perhaps the most important conservation issue for Brazil today,” said Firenside.
So, is there any chance of building a bridge across the Amazon in the near future?
“I believe that a bridge will not be built unless the need outweighs the difficulties and the cost,” Kaufman said. “Personally, I doubt this will happen soon, unless there are unexpected economic developments in the region.”
Originally published on Live Science.
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