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Here’s Why You’ll Never Find a Bridge Across the Amazon River

People living in the Amazon basin rely on boats and ferries to cross the headwaters spanning from the Andes to the Atlantic delta.

BY GREEN MATTERS STAFF

PUBLISHED DEC 22, 2024

Amazon river snaking through the basin studded with greenery and soil (Representative Cover Image Source: Pexels | Gustavo Denuncio)

Unlike millions of years ago when humans crossed lakes and rivers by using trails of rocks or wedges of wood, today there are bridges. Given the possibility of bridges, it seems quite unusual that the second-longest river in the world has no bridge. Amazon River, which snakes through a 4,300-mile stretch, crossing a mosaic of cities in the South American continent, doesn’t have a single bridge. Not that its pink-nosed dolphins or giant black anacondas will emerge from the waters and swallow the bridge. The reason is not even a lack of financial budget. Instead, the reason is quite simple, as Walter Kaufmann, chair of Structural Engineering at the Swiss Federal Institute of Technology (ETH), Zurich, revealed to Live Science.

Aerial view of a river (Representative Image Source: Pexels | Mikhail Nilov)

"There is no sufficiently pressing need for a bridge across the Amazon," said Kaufmann. He said that although there are technological and logistic difficulties, there is little to no need for bridges as there are not many roads to connect these bridges to, in the Amazon basin. There would be financial difficulties too. “Its extensive marshes and soft soils would necessitate very long access viaducts [a multi-span bridge crossing extended lower areas] and very deep foundations and this would require hefty financial investment,” explained Kaufmann.

River snaking through a forest (Representative Image Source: Pexels | Dom Gould)

But above and beyond these factors, the primary factors underlying the absence of bridges in the Amazon is the unusual and abrupt pattern and rhythm of its waters. This issue might not seem major, but for engineers, it is gravely serious. Conde Nast Traveller (CNT) describes this as a “civil engineer’s worst nightmare.” Elaborating on this, CNT wrote that the river might not swell too much during the dry season. But “During the rainy season, the river rises thirty feet, and crossings that were once three miles wide can balloon to thirty miles in a matter of weeks.”

A manmade bridge across a river. (Representative Image Source: Pexels | Luis Alberto Arias)

The soft sediment of the river is constantly eroding and the river is often full of debris, including the floating vegetation islands called “matupás,” which can measure up to 10 square acres. "The environment at the Amazon is certainly among the most difficult [in the world]," added Kaufmann. "Bridges across straits are also challenging if the water depth is deep, but at least you know that construction is possible using pontoons, for example." He said the river’s geology would be a “unique challenge” for engineers and construction workers.

A river with dense vegetation on either side. (Representative Image Source: Pexels | Tom Fisk)

However, there are currently no bridges on the Amazon River "doesn't mean it won't happen," Philip Fearnside, an American biologist, scientist and conservationist from Brazil, told Live Science. But Kaufmann is still reluctant about the idea of having such a bridge. "I think a bridge would only be built if the need dominates over the difficulties and cost," Kaufmann said. "Personally, I doubt that this will happen soon unless there are unforeseen economic developments in the region." In the end, no one knows whether a bridge would be feasible for the Amazon River or not. But until then, the school of gray-brown manatees or sea cows, as well as the electric eels don’t need to fret about the noise pollution that may disturb their peace with honking vehicles, hissing machines, or chattering humans.