The Amazon River is the second-longest river in the world and one of the world's most important rivers.
It boasts more freshwater by volume than any other river; is home to the world's biggest species of river dolphin; and includes up to 60 kinds of piranhas.
Given that the Amazon runs through three nations (Peru, Colombia, and Brazil) and that the river's basin is home to more than 30 million people, according to the World Wildlife Fund, no bridges cross the river.
Are there any inherent challenges to constructing such buildings in a rainforest with swaps, huge ponds, and dense undergrowth? Are there any financial obstacles? Is it simply not worth the time?
The Amazon Curse
LUIS ROBAYO/AFP via Getty Images
The Amazon's lack of bridge crossings is unusual when compared to other of the world's most well-known rivers, as per LiveScience.
In Cairo alone, there are around nine Nile-spanning bridges; more than 100 bridges have been erected over Asia's greatest river, the Yangtze, in the last 30 years; and Europe's Danube, which is barely one-third the length of the Amazon, has 133 bridge crossings.
For much of its 4,300-mile (6,920-kilometer) length, the Amazon passes through sparsely inhabited areas, which means there are few main highways to which any bridge may link.
Boats and ferries are an established way of transferring goods and people from bank to bank in the cities and villages that surround the river.
Bridges are only designed to make travel somewhat faster, not because they are necessary.
According to Walter Kaufmann, chair of Structural Engineering (Concrete Structures and Bridge Design) at the Swiss Federal Institute of Technology Zurich, the Amazon is not an ideal place for bridge-builders since it contains a variety of natural stumbling hurdles that engineers and construction workers would have to overcome.
Furthermore, the building would be highly difficult due to the varying locations of the river's channel with the seasons, as well as significant fluctuations in water depth.
Although no bridges traverse the Amazon, one does cross the Negro River, which is one of its primary tributaries.
The Ponte Rio Negro bridge, which was built in 2011, connects Manaus with Iranduba and is the only large bridge that crosses any Amazon tributary to date.
While no specific plans for a bridge over the Amazon exist, this does not rule out the possibility, according to Philip Fearnside, an American biologist, scientist, and conservationist who has spent much of his career in Brazil.
"The river's wetlands and fragile soils would necessitate extremely lengthy access viaducts and very deep foundations," according to Kaufman, necessitating a significant financial commitment, as per Unilad.
The construction of a bridge would also be hampered by the "pronounced changes" in water depth that occur throughout the year, as Kaufmann explained, "The Amazon environment is unquestionably among the most challenging in the world."
Bridges across straits are equally difficult to build if the water is deep, but at least you know that pontoons, for example, may be used.
Because of the way the Amazon varies with the seasons, pontoons, or floating buildings, would not function in most areas, Kaufmann further said.
