Walking across Space: Incan Rope Bridges (HA)
You’re standing at the edge of a canyon high in the Andes Mountains, looking down at a raging river far below. You look
across to the other side. The only way to get there is to walk across a narrow rope bridge. You grit your teeth and step out into
space. The bridge sinks beneath your weight. Will the bridge hold? Will it flip you over into the gorge below? Don’t worry—
this bridge was built by people who really know what they’re doing!
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The Incas lived in a land of high mountains separated by rivers and deep valleys. They built a vast system of roads to help them travel
and communicate. They also built amazing bridges that crossed the vast chasms between cliffs and canyons. These bridges were made
of thick rope cables woven from grass. That’s right—grass.
For centuries, these rope bridges played a critical role in transportation throughout the Andes Mountains. Massachusetts Institute of
Technology (MIT) professor John Ochsendorf is a structural engineer who has spent years studying Incan rope bridges. He thinks that
the bridges were just as important as the Incan road system. They allowed the Incas to cross natural barriers, such as canyons and
rivers. Without the amazing engineering that created these rope bridges, the Incas could not have connected the roads into the effective
communication system that helped them create and control their large empire.
Bridges Made from Grass
In the Quechua language, a grass rope bridge is called a Keshwa-chaka. According to Ochsendorf, there were two types of rope
bridges: large and small. Each type was carefully planned and maintained. There is evidence that the Incan emperor himself drew
plans for large bridges and made sure that they were repaired and protected.
Large bridges had a Chaka Camayoc, which means “bridgekeeper” in the Quechua language. Living at the bridge, the Chaka
Camayoc was responsible for guarding and repairing it. Large bridges were usually located on the Royal Road, built between the
present-day cities of Cuzco, Peru, and Quito, Ecuador.
Smaller bridges connected rural communities to one another and to the Royal Road. The local people were responsible for building
and maintaining them as part of their annual service to the empire. Working together, they repaired or rebuilt these bridges every year.
Building a Rope Bridge
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The last remaining Incan rope bridge is believed to be located in the remote village of Huinchiri, Peru. It hangs about two hundred feet
over the Apurimac River and spans a distance of over one hundred feet. People in the area use a modern metal bridge for everyday
transportation across the river. But each year, Quechua villagers hold a three-day festival during which they cut down the old rope
bridge and build a new one. Using weaving and construction techniques that have passed from generation to generation, they honor
their culture and ancestors. Tourists come from around the world to watch the villagers rebuild the bridge.
During the festival, villagers organize the work in the same way it has been done for centuries. Each household is responsible for a
certain job. There are four key tasks in constructing a bridge: making rope; braiding it into cables; repairing or rebuilding the stone
anchors on either side of the river; and making the ties, the handrails, and a floor system.
The basic material that makes up the huge cables needed to hold up the bridge is a thin, two-ply rope. Hundreds of families work
before the festival begins to make this rope. They start by gathering dry stalks of grass. Then they twist pieces of grass together. As
they add grass, the rope becomes longer and longer. The villagers make the rope in lengths of about fifty yards. Approximately ten
miles of rope are needed to build the bridge.
On the first day of the festival, construction begins. Families bring their handmade thin ropes to the bridge site. The chief bridge
builder and the priest make offerings to Paca Mama, or Mother Earth. They ask that she bless their work. They also ask that the bridge
stay safe and strong until they rebuild it next year.
Next, the men make large cables. They braid the thin ropes together, three at a time, to make thicker cables. Then they braid these
cables together to make even thicker ones. Each cable measures 6 inches in diameter, weighs about 150 pounds, and is 150 feet long.
Six of these big cables are needed to make the bridge. Four cables form the bridge floor to carry the weight of people and animals, and
the remaining two cables serve as handrails.
On the second day, the villagers cut down the old bridge and let it fall into the river. Then the men put up new cables. A guide rope is
attached to each cable. Using the guide rope, the men pull each cable across the river. They lift each one to the top of the cliff on the
other side of the canyon. Then, they pull on the cables to make sure they are very tight. Finally, they connect the cables to strong
timbers and stone anchor blocks located on each side of the river.
On the festival’s final day, people gather at the bridge in colorful party clothes. They watch the current bridgekeeper connect rope ties
from the floor cables to the handrail cables. Other men lay down cross-ties, or sticks that will help keep the floor cables in place.
Finally, they lay reed floor mats over the cross-ties and floor cables to complete the bridge.
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Walking Across the Rope Bridge
Once the bridge is finished, a celebration begins. The villagers may offer guests or tourists a traditional Quechua meal. Then anyone
who wants to is invited to walk across the bridge. Would you walk across it?
When Spanish soldiers first saw these bridges, they were terrified. Some soldiers crawled across them on their hands and knees. The
bridges were strong and safe, however. The Spanish even crossed them with their horses and cannons.
Ephraim George Squier, an American visitor to Peru in the 1870s, gave good advice about crossing the rope bridge over the
Apurimac. He wrote, “It is usual for the traveler to time his day’s journey so as to reach the bridge in the morning, before the strong
wind sets in; for, during the greater part of the day, it sweeps up the canyon of the Apurimac with great force, and then the bridge
sways like a gigantic hammock, and crossing is next to impossible.”
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An American scientist who crossed the newly rebuilt bridge described her walk with words that echoed those of Ephraim Squier from
the 1870s. As she crossed slowly to keep the bridge from swaying too much or flipping over, she said, “I want to look down, but I’m
afraid to look down, so I’m looking at everybody across. I know I can do this. I think I’m going to be sick. No, I’m not.”
Many tourists accept the invitation to walk across the newly finished bridge. After watching its construction, they feel sure that it is
sturdy and safe. Laboratory tests done by Professor John Ochsendorf show that the bridge is quite strong. It can hold 56 people spread
out in a row across the bridge at one time, or 4,200 pounds of weight.
What the Incas accomplished centuries ago makes their Quechua descendants very proud. They know that their ancestors were gifted
engineers. The Incas solved the problem of connecting roads by using the resources at hand. They also know that these bridges
function well, since they were rebuilt again and again for more than 400 years, until metal bridges started to replace them in the 19th
century. Anyone watching the Incas’ Quechua descendents build a bridge in just three days will see that they are living examples of a
way of life that has endured for centuries.