Related Movable No Falsework required No Ancestor Simple suspension bridge | Span range Short Design effort Advanced for its time Bridge type Suspension bridge Carries Pedestrian, Livestock | |
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Descendant Simple suspension bridge Similar Q'iswa Chaka, Simple suspension bridge, Inca Bridge, Rope bridge, Wanakawri | ||
Inca rope bridges are simple suspension bridges over canyons and gorges and rivers (pongos) constructed by the Inca Empire. The bridges were an integral part of the Inca road system and exemplify Inca innovation in engineering. Bridges of this type were useful since the Inca people did not use wheeled transport - traffic was limited to pedestrians and livestock - and they were frequently used by Chasqui runners delivering messages throughout the Inca Empire.
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Construction and maintenance
The Incas used natural fibers found within the local vegetation to build bridges. These fibers were woven together creating a strong rope and were reinforced with wood creating a cable floor. Each side was then attached to a pair of stone anchors on each side of the canyon with massive cables of woven grass linking these two pylons together. Adding to this construction, two additional cables acted as guardrails. The cables which supported the foot-path were reinforced with plaited branches. This multi-structure system made these bridges strong enough to even carry the Spaniards while riding horses, after they arrived. The design naturally sags in the middle.
Part of the bridge's strength and reliability came from the fact that each cable was replaced every year by local villagers as part of their mit'a public service or obligation. In some instances, these local peasants had the sole task of maintaining and repairing these bridges so that the Inca highways or road systems could continue to function.
Repairing these bridges was dangerous, as those performing repairs often met death. An Inca author praised Spanish masonry bridges being built, as this rendered the need to repair the rope bridges moot.
Famous examples
The greatest bridges of this kind were in the ApurÃmac Canyon along the main road north from Cusco; a famous example spans a 148-foot gap that is supposed to be the inspiration behind Thornton Wilder's 1928 Pulitzer Prize winning novel The Bridge of San Luis Rey (1927).
Made of grass, the last remaining Inca rope bridge, reconstructed every June, is the Q'iswa Chaka (Quechua for "rope bridge"), spanning the Apurimac River near Huinchiri, in Canas Province, Quehue District, Peru. Even though there is a modern bridge nearby, the residents of the region keep the ancient tradition and skills alive by renewing the bridge annually in June. Several family groups have each prepared a number of grass-ropes to be formed into cables at the site; others prepare mats for decking, and the reconstruction is a communal effort. The builders have indicated that effort is performed to honor their ancestors and the Pachamama (Earth Mother).