More than 6,400 kilometres long, the Amazon River is surprisingly devoid of a single official bridge. Considering humanity’s relationship with nature, it is quite surprising that there are no bridges over such a long river. But of course there are some reasons for this.
One of the most important reasons is that there is not much demand to cross the Amazon. In addition to the fact that the human population is not very dense in the depths of the rainforest, the number and density of infrastructure and roads is also quite sparse. So, at least relatively speaking, there is not much need to cross from one side of the river to the other.
‘There is no sufficiently urgent need to build a bridge across the Amazon,’ said Walter Kaufmann, head of the Department of Structural Engineering (Concrete Structures and Bridge Design) at the Swiss Federal Institute of Technology in Zurich, in an interview with Live Science in 2022. ‘Of course, there are also technical and logistical difficulties,’ Kaufmann also pointed out.
Technical and logistical challenges
The dense nature of the rainforest makes it difficult to establish human settlements and necessary infrastructure in general. In addition to the soft and unpredictable ground, it is easy for man-made structures to be quickly weakened and rendered unusable by the harsh conditions of the rainforest, such as relentless vegetation and heavy rainfall.
Therefore, any attempt to build a bridge over a river will quickly collapse or become unusable unless it is perfectly designed to withstand all hazards. As you can imagine, the cost of building a structure to meet these challenging conditions increases at a similar rate.
Although it does not attract much attention in general, in fact the Amazon jungle is full of the remains of human settlements that have disappeared into nature over the centuries. New imaging technologies show that there may be more than 10,000 pre-Columbian archaeological sites throughout the Amazon basin. Unlike archaeological remains of ancient cultures in temperate regions of the world, Amazonian structures were submerged, swallowed by vegetation and buried.
Even the motorway could not withstand the conditions
A modern example of all these challenges is the famous BR-319 motorway, an 870 kilometre stretch of unspoilt Amazon rainforest from Manaus to Porto Velho. Built in the early 1970s under Brazil’s military dictatorship, the motorway was abandoned in 1988 due to its rapid deterioration, requiring constant repairs and being uneconomical to maintain.
It is also important that no more structures are built to protect the Amazon, an incredibly rich and unique biodiversity and cultural hotbed that is already under enormous pressure from the logging and mining industries. Building more roads and bridges in the Amazon forest could put even more pressure on this important natural landscape, which is already at risk. Research shows that the vast majority of deforestation (95%) occurs within 5.5 kilometres of a road, providing access for foresters, vehicles and heavy machinery.
A 2022 study used artificial intelligence to identify rural (often unofficial and illegal) roads in the Brazilian Amazon from satellite imagery, identifying 3.46 million kilometres of roads. The researchers then used these findings to see how new roads affect deforestation, forest fires and land fragmentation.
