How many Bridges Cross The Amazon River? The Amazon River is the world’s second-longest river and one of the planet’s most significant waterways. It contains more fresh water by volume than any other river, is home to the world’s largest species of river dolphin, and hosts 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.
Given the Amazon flows through three countries (Peru, Colombia and Brazil) and more than 30 million people live in the river’s basin, according to the World Wildlife Fund, it seems somewhat improbable that no bridges span the river. So why is this the case? Are there fundamental difficulties with building such structures in a rainforest containing swamps, extensive wetlands and deep, thick undergrowth? Are there financial barriers? Or is it simply not worth the effort?
How many Bridges Cross The Amazon River?
When compared with some of the world’s other most recognisable rivers, the Amazon’s lack of bridge crossings is an oddity. There are about nine Nile-spanning bridges in Cairo alone; more than 100 bridges have been completed in the last 30 years across the Yangtze, Asia’s premier river; while Europe’s Danube, which is only one-third as long as the Amazon, has 133 bridge crossings.
So what’s the deal with the Amazon?
“There is no sufficiently pressing need for a bridge across the Amazon,” Walter Kaufmann, chair 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, for much of its 4,300-mile (6,920 kilometers) length, meanders through areas that are sparsely populated, meaning there are very few major roads for any bridge to connect to. And in the cities and towns that border the river, boats and ferries are an established means of moving goods and people from bank to bank, meaning there is no real need for bridges to be built, other than to make trips slightly quicker.
“Of course, there are also technical and logistical difficulties,” Kaufmann noted.
According to Kaufmann, the Amazon is far from an ideal location for bridge builders, as it has an array of natural stumbling blocks that would need to be conquered by engineers and construction workers.
For example, 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, Kaufmann said. Additionally, the changing positions of the river’s course across the seasons, with “pronounced differences” in water depth, would make construction “extremely demanding.” This is due, in part, to the river’s water level rising and falling throughout the year and the soft sediment of the riverbanks eroding and shifting seasonally, according to the Amazon Waters initiative.
Kaufmann noted that, while these particular issues are not unique to the Amazon, “they are particularly severe” there.
“The environment at the Amazon is certainly among the most difficult [in the world],” Kaufmann said. “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.”
Pontoons, or floating structures, are not a solution that would work in most parts of the Amazon, Kaufmann said, because the river is hugely impacted by seasonal variances, which adds an additional layer of complexity.
For instance, during the dry season — between June and November — the Amazon averages a width of between 2 and 6 miles (3.2 and 9.7 km), while in the wet season — December through April — the river can be as wide as 30 miles (48 km), and the water level can be 50 feet (15 meters) higher than it is during the dry season, according to Britannica.
Welcome to the jungle! We don’t have a bridge.
The Amazon runs over 4,300 miles from its headwaters in the Andes to its massive delta on the Atlantic. While the 25 million people who live on or near its banks span Brazil, Peru, and Colombia, living in sprawling metropolitan cities and tiny tribal villages, all have one thing in common: to cross to the other side, they’ll need to jump in a boat or hop on a ferry. No road crosses the Amazon. It divides an entire continent nearly in two.
Bridges in the Amazon would work great… until January.
For most of its length, the Amazon isn’t anywhere close to too wide to bridge—in 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.
The soft sediment that makes up the river bank is constantly eroding, and the river is often full of debris, including floating vegetation islands called matupás, which can measure up to 10 square acres. It’s a civil engineer’s worst nightmare.
Where we’re going, we don’t need roads.
But the real reason for the lack of bridges is simply this: the Amazon Basin has very few roads for bridges to connect. The dense rainforest is sparsely populated outside of a few large cities, and the river itself is the main highway for those traveling through the region.
Macapá, on the north shore of the Amazon delta, is a city of half a million people, but there’s not a single road to connect it to the rest of Brazil. If you rent a car there, the only direction to drive it is north toward French Guiana.
The basin’s first bridge is good for commuters but bad for trees.
For years, ferry traffic between Manaus, Brazil and its sister town Iranduba was slow and increasingly crowded. The crossing also cost up to $30 a passenger. So in 2010, Brazil built a two-mile-long cable-stayed bridge connecting the two cities. This bridge doesn’t technically cross the main course of the Amazon; it crosses the Rio Negro, the Amazon’s largest tributary.
But it’s the river system’s very first bridge, and citizens rejoiced. Environmentalists, however, aren’t fans of Manaus’s new bridge and highway projects. In the past, road-building in the Amazon has been the first step to development and deforestation.
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