The Amazon River is the second longest river in the world and one of the most important waterways on the planet. It contains more fresh water by volume than any other river, is home to the largest river dolphin species in the world and is home to 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 the Amazon River: bridges.
With the Amazon crossing three countries (Peru, Colombia and Brazil) and more than 30 million people living in the river basin, according to the World Wildlife Fund (opens in a new tab), it seems a bit unlikely that there are no bridges over the river. So why is this the case? Are there fundamental difficulties in building these structures in a rainforest that contains interchanges, extensive wetlands, and deep, thick undergrowth? Are there financial barriers? Or is it just not worth the effort?
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The Amazon anomaly
Compared to some of the other most recognizable rivers in the world, the lack of bridges on the Amazon is a curiosity. In Cairo alone there are about nine bridges across the Nile; more than 100 (opens new tab) Bridges have been completed in the last 30 years across the Yangtze River, Asia’s main river; while the Danube of Europe, which is only 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 strong enough need for a bridge across the Amazon,” said Walter Kaufmann, president of Structural. Engineering (Concrete structures and bridge design) of the Swiss Federal Institute of Technology (ETH) Zurich, told Live Science in an email.
The Amazon, largely 4,300 miles (6,920 kilometers) long, meanders through sparsely populated areas, meaning there are very few major roads to connect any bridge to. And in cities and towns along the river, ships and ferries are an established means of transporting goods and people from one bank to another, that is, there is no real need to build bridges other than trips a little faster.
“Of course, there are also technical and logistical difficulties,” Kaufmann noted.
According to Kaufmann, the Amazon is far from an ideal place for bridge builders, as it has a wide variety of natural obstacles that should be conquered by engineers and construction workers.
A map of the Amazon River Basin with the Amazon River highlighted. (Image credit: By Kmusser – This vector image includes elements that have been extracted or adapted from this file :, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid= 24862395)
For example, its extensive wetlands and soft soils would require “very long access viaducts.” [a multi-span bridge crossing extended lower areas] and very deep foundations, “Kaufmann said.” In addition, the changing positions of the river’s stations, with “pronounced differences” in water depth, would make construction “extremely demanding.” This is due in part to the rising and falling water level throughout the year and the gentle sediment on the banks that erodes and shifts seasonally, according to the Amazon Waters initiative (opens in a new tab).
Kaufmann noted that while these particular issues are not unique to the Amazon, “they are especially serious” there.
“The environment in the Amazon is certainly one of the most difficult [in the world]”Bridges across the straits are also a challenge if the depth of the water is deep, but at least you know construction is possible with pontoons, for example,” Kaufmann said.
Pontoons, or floating structures, are not a solution that works in most parts of the Amazon, Kaufmann said, because the river is severely affected by seasonal variations, which adds an extra layer of complexity. For example, during the dry season, between June and November, the Amazon has an average width of 2 to 6 miles (3.2 to 9.7 km), while in the wet season, from December to April, the river can be up to 30 miles wide. (48 km) and the water level may be 50 feet (15 meters) higher than during the dry season. according to Britannica (opens in a new tab).
“This challenge would be unique,” Kaufmann said.
Therefore, in addition to the immediate need for a bridge across the Amazon, the processes involved in building one would be considerable.
Related: What is the World’s Largest Freshwater Fish?
A bridge too far?
It is worth mentioning that, although there are no bridges that cross the Amazon, there is one that crosses the Negro River, its main tributary. Named Ponte Rio Negro, the bridge, completed in 2011, connects Manaus and Iranduba and, to date, is the only major bridge that crosses any tributary of the Amazon.
But while there are no specific plans for a bridge over the Amazon, “that doesn’t mean it won’t happen,” said Philip Fearnside, an American biologist, scientist and conservationist who has spent much of his career in the United States. Brazil. he told Live Science.
In 2019 Jair Bolsonaro, President of Brazil, declared that he wanted a bridge (opens in a new tab) via Amazon which will be built as part of its “Rio Branco Project”, but no progress has been made yet. “It would be very expensive compared to the economic benefits it would bring,” Fearnside noted.
Tourist boats cross the Amazon River near Manaus, Brazil. (Image credit: Vittoriano Rastelli via Getty Images)
Once the Rio Negro Bridge was completed, provisional plans were drawn for a bridge over the Upper Amazon, known as the Solimões River, in the municipality of Manacapuru, which would connect the BR-319 road with Manaus and eliminate the need for a ferri. travessa.
“BR-319 is a high political priority, but it has no economic justification,” Fearnside said. “It’s cheaper to transport products from factories in the Manaus Free Trade Zone to São Paulo by water.”
In addition, as stated in a 2020 commentary that Fearnside wrote for the environmental news site mongabay (opens new tab) Regarding the proposed development of the BR-319, the creation of this bridge “would give deforestation access to about half of what’s left of the country’s Amazon rainforest, and is perhaps the most significant conservation issue for Brazil today, ”Fearnside said.
So, is there any possibility that a bridge could be built across the Amazon in the near future?
“I think a bridge would only be built if the need prevails over difficulties and cost,” Kaufmann said. “Personally, I doubt this will happen soon, unless there is unforeseen economic developments in the region.”
Originally published in Live Science.