Ancient Andean engineering: the amazing suspension bridges of the Inca Empire
25 November 2019
In previous posts we have told about the Qhapac Ñan, the Inca’s 25,000 mile-long (40,000 km) network of Inca roads, which connected all corners of the huge Inca Empire. Its pathways are often steep, and fine stone stairways make up some parts of it.
The Qhapac Ñan is a marvel of Inca engineering, and much of it remains intact and is still used by local Andean people to this day.
However, the Andes Mountains are criss-crossed by dozens of rivers, streams and deep gorges, and Inca roads needed to cross over formidable barriers. In the Andes rivers are large, very swift and filled with raging currents, especially in rainy season.
Connecting a vast empire
Most Andean canyons and gorges are extremely precipitous. To solve the problem of interconnecting their roads, the Incas and their predecessors put all their amazing ingenuity and building skills into making strong suspension bridges, which made travel possible all across the Empire.
They made over 200 major suspension bridges, and only one remains today, the 600-year old Q’eswachaka Bridge over the Apurimac River, about three or four hours south of Cusco city.
Building the bridges
How were Inca bridges built? Bridge construction was an important community event, in which hundreds of community members participated, led by the chakakayoc, the Inca bridge specialists. Since the grass ropes decayed after a time, the bridges were rebuilt by the local community every year or two.
This activity requires good balance and strong nerves. Needless to say, crossing Inca bridges, so high above roaring rivers, was not for those afraid of heights.
Inca bridges were made of strong Andean grasses, particularly of ichu grass, which was made into ropes, and anchored with leather ties onto solid stone supports. The grasses were first braided into threads, and the threads then into thick ropes, all by hand in a time-consuming process that produced natural fiber cables that could support thousands of pounds.
The Q’eswachaka Bridge, for example, is made of four thick cables, two above for suspension, and two fiber cables to hold its narrow floor below, made of straw mats. Additional side cables provide handholds.
The science behind ancient bridges
Scientists who have studied the 90 foot-long Q’eswachaka Bridge have proposed that that it could hold up to 16,000 lbs. Other stronger Inca bridges might have supported up to 200,000 lbs.
Since the Incas did not have horses and mainly traveled on foot, their bridges were strong enough for any transportation purpose, including the crossing of Inca armies.
Another interesting aspect of the Inca bridges is that they could be taken down quickly. In the 16th century Inca war of resistance against the Spanish invaders, many bridges unfortunately were burnt or destroyed, to impede the movement of the Spaniards as they approached. Inca bridges also inspired writer Thornton Wilder’s novel The Bridge At San Luis Rey.
Today, the Q’eswachaka Bridge continues to span the mighty Apurimac. As the last remaining Inca bridge, it has become a center of attention for people worldwide. Every year in mid-June, the local community holds a festival to rebuild and bless the bridge.
In the past few years, visitors have been coming to witness this event, camping out nearby. After four days of celebrations, visitors are allowed to cross the bridge, always after an offering of coca and a prayer to the Andean Apus, the mountains and other deities of nature.
In the summer of 2015 a large replica of the Q’eswachaka Bridge was built for the Folklife Festival on the Mall in Washington, D.C., with the help of Peruvian engineers.
It is hoped that with renewed interest in Inca bridges, more will be rebuilt at key locations in Peru, and will once again span the great Andean rivers, to the delight of adventurous visitors.
You can enjoy the opportunity to visit the Q’eswachaka Bridge on a visit to Cusco. It is a good distance away, a full day of travel roundtrip, and must be arranged beforehand.
Please contact us at andeanexcursions.travel to explore great options for encountering Inca culture and its most important sites in Cusco in person on our outstanding acclimatization tours. The Andes are awaiting your visit!