by The Amazon River is the second longest river in the world and one of the most important waterways in the world. It contains more freshwater by volume than any other river, is home to the world’s largest species of river dolphin and is home to 100 species of electric fish and up to 60 species of piranhas.
Yet, despite its many and varied qualities, there is something that cannot be found on the Amazon River: bridges.
Since the Amazon flows 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 new tab), it seems somewhat unlikely that there are no bridges over the river. So why is this the case? Are there fundamental problems in building such structures in a rainforest with swamps, extensive wetlands and deep, thick undergrowth? Are there financial barriers? Or is it just not worth it?
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The Anomaly of the Amazon
Compared to some of the world’s most recognizable rivers, the Amazon’s lack of bridges is an oddity. There are about nine Nile Bridges in Cairo alone; more than 100 (opens in new tab) bridges have been completed in the past 30 years across the Yangtze, Asia’s most important river; while the European Danube, which is only a third as long as the Amazon, 133 bridge crossings (opens in new tab)†
So what’s the deal with the Amazon?
“There is not a sufficiently urgent need for a bridge across the Amazon,” said Walter Kaufmann, Structural . president Engineering (Concrete Structures and Bridge Design) from the Swiss Federal Institute of Technology (ETH) Zurich, told Live Science in an email.
The Amazon, for much of its 6,920-kilometer length, meanders through sparsely populated areas, meaning there are very few main roads a bridge can connect to. And in the towns and villages that border the river, boats and ferries are a regular means of moving goods and people from bank to bank, meaning there’s no real need to build bridges, except to travel a little faster.
“Of course there are also technical and logistical problems,” Kaufmann noted.
According to Kaufmann, the Amazon is far from an ideal location for bridge builders, as it has a range of natural stumbling blocks that must be overcome by engineers and construction workers.
For example, the extensive swamps and soft bottoms would require “very long access overpasses” [a multi-span bridge crossing extended lower areas] and very deep foundations,” and this would require significant financial investment, Kaufmann said. seasons, with “marked differences” in water depth, would make the construction “extremely demanding”. This is partly due to the fact that the river’s water level rises and falls throughout the year and that the soft sediment of the riverbanks erodes and shifts seasonally, according to the Amazon Waters Initiative (opens in new tab)†
Kaufmann noted that while these particular problems are not unique to the Amazon, they are “particularly serious” there.
“The environment on the Amazon is certainly one of the most difficult [in the world]”Bridges over straits are also a challenge when the water is deep, but at least you know that construction is possible with pontoons, for example.”
Pontoons, or floating structures, aren’t a solution that would work in most parts of the Amazon, Kaufmann said, because the river is greatly affected by seasonal variations, adding an extra layer of complexity. For example, during the dry season – between June and November – the Amazon is on average between 2 and 6 miles (3.2 and 9.7 km) wide, while in the wet season – December to April – the river can be as wide as 30 miles. are (48 km), and the water level can be 15 meters higher than during the dry season, according to Britannica (opens in new tab)†
“This challenge would be unique,” Kaufmann said.
So, aside from not immediately needing a bridge across the Amazon, the processes required to build one would be significant.
Related: What is the largest freshwater fish in the world?
A bridge too far?
It is worth noting that while there are no bridges crossing the Amazon, there is one that crosses the Negro River, its main tributary. Completed in 2011, the bridge, called the Ponte Rio Negro, connects Manaus and Iranduba and is to date the only major bridge crossing a tributary of the Amazon.
But while there are no concrete plans for a bridge across the Amazon, “that doesn’t mean it won’t happen,” Philip Fearnside, an American biologist, scientist and conservationist who has spent much of his career in Brazil, told Live Science. com.
In 2019, Brazil’s president Jair Bolsonaro said, stated that he wanted a bridge (opens in new tab) about to build the Amazon as part of its “Rio Branco Project”, but so far no progress has been made. “It would be very expensive compared to the economic benefits it would bring,” Fearnside noted.
After the completion of the Ponte Rio Negro, preliminary plans were drawn up for a bridge over the Upper Amazon – known as the Solimões River – in the municipality of Manacapuru, which would connect the BR-319 highway to Manaus and eliminate the need for a ferry. remove intersection.
“BR-319 has a high political priority, but has no economic justification,” Fearnside said. “It is cheaper to transport products from the factories in the Manaus Free Trade Zone to São Paulo by water.”
Additionally, as stated in a 2020 commentary, Fearnside wrote for the environmental news site Mongabay (opens in new tab) with regard to the proposed development of the BR-319, the creation of such a bridge would “give” deforesters access to about half of what is left of the country’s Amazon rainforest, and that is arguably the most sweeping conservation issue for Brazil today,” Fearnside said.
So, is there a chance that a bridge across the Amazon could be built in the near future?
“I think a bridge can only be built if necessity outweighs the difficulties and the cost,” Kaufmann said. “Personally, I doubt this will happen anytime soon unless there are unforeseen economic developments in the region.”
Originally published on Live Science.
