Bridges and Tambos of the Qhapaq Ñan

The great Inca road system, the Qhapaq Ñan, could not have functioned without two complementary kinds of infrastructure: the bridges that carried the road across rivers and gorges, and the tambos (way stations) that provided lodging, food, and supplies to travelers, armies, and the officials of the imperial state. Together, the bridges and tambos of the Qhapaq Ñan constituted the operational backbone of the road system, allowing it to function as a continuous network of communication and transportation across a geography of extreme mountains, deep valleys, and powerful rivers. The chroniclers Pedro Cieza de León, Miguel Cabello Valboa, and Bernabé Cobo all describe the bridges and tambos in detail, and the surviving archaeological and historical evidence allows for a substantial reconstruction of their construction, maintenance, and operation.

Bridges of the Inca Road System

The Inca built several distinct types of bridges, each suited to a particular geographical and engineering context. The most famous are the suspension bridges of braided grass rope (ichu), which were used to span the deep gorges of the high Andes. The principal construction material was the tough mountain grass ichu (Stipa ichu), twisted into cables of varying thickness depending on the load to be supported. The cables were anchored to stone abutments on either side of the river, and a roadway was formed by laying additional cables across the gap and weaving them into a continuous walking surface. The most substantial Inca bridges used several parallel cables and were capable of supporting the weight of loaded llamas and even the elaborate litters in which the Sapa Inca was sometimes carried.

The most famous Inca bridge was the bridge over the Apurímac River, on the road between Cusco and the Collasuyu provinces. The chronicler Miguel Cabello Valboa, writing in 1586, recorded that the bridge was reconstructed annually by the communities on either bank as part of their mit’a labor obligations, and that the rope for the bridge was made from the ichu grass gathered in the surrounding mountains. The bridge spanned the Apurímac at a height of more than 60 meters above the river and was more than 30 meters in length. A later Spanish account records that the bridge was so substantial that it could support the weight of a mounted horse, a significant engineering achievement given the materials.

Other bridge types used in the Inca road system included:

Stone bridges, generally used in the highlands where suitable rock was available. The stone bridges of the Inca are typically simple arched structures of carefully fitted ashlar masonry.
Timber bridges, used in the lowland forests and on the eastern Andean slopes, with main beams supported by stone or timber piers.
Beam bridges, in which a single large log or stone slab was placed across a narrow gorge.
Causeways and ford improvements, particularly in the coastal desert, where rivers were often shallow enough to be forded.

The maintenance of the bridges was the responsibility of the surrounding communities, who were required by the mit’a system to provide labor for the annual reconstruction of the rope bridges. The destruction or disrepair of a bridge was treated as a serious matter, and the imperial state kept records of the bridges and their condition in the provincial quipus.

Tambos: Way Stations of the Empire

The tambos (Quechua tampu) were the way stations that provided lodging, food, and supplies along the Qhapaq Ñan. They were located at intervals of roughly 20 to 30 kilometers — the distance that a loaded llama or a marching soldier could travel in a day — and they ranged in size from small shelters with a few rooms to large complexes with hundreds of rooms, storehouses, and administrative offices. The Inca maintained an estimated 2,000 or more tambos across the empire, although the exact number is uncertain.

The functions of the tambos were multiple. They served as inns for travelers, including officials, soldiers, and mit’a laborers; storage facilities for food, military supplies, cloth, and other items; administrative centers for the surrounding districts; military installations that could be defended in the event of attack; and rest stops for the chasqui couriers, who carried messages in relay along the road system.

The Spanish chronicler Pedro Cieza de León, who traveled the Qhapaq Ñan in the 1550s, provided one of the most detailed early descriptions of a tambo. The tambo he described in the central highlands of Peru was a large complex of buildings, with separate quarters for the Sapa Inca and high officials, barracks for soldiers, storehouses for food and supplies, and quarters for the servants and laborers who maintained the installation. The food supplies stored at the tambo, Cieza de León reported, were substantial: maize, dried meat, potatoes, quinoa, and chicha, sufficient to support the travelers, soldiers, and laborers who passed through.

Architectural Forms

The architectural forms of the tambos varied across the empire, but a number of common features can be identified. The most elaborate tambos were built in the imperial style, with finely cut ashlar masonry, rectangular rooms arranged around central plazas, and ceremonial precincts. The tambo of Huanuco Pampa, in the central Peruvian highlands, is the largest and best-preserved example of an Inca tambo, with a complex of more than 700 rooms arranged around a central plaza. The site, excavated by John Hyslop in the 1970s and 1980s, served both as an administrative center and as a major storage facility.

Maintenance and Operation

The maintenance of the bridges and tambos was one of the principal tasks of the mit’a labor system. The reconstruction of the rope bridges was an annual event, typically performed in the dry season (May to September) before the rains returned. The work of gathering the ichu grass, twisting it into cables, and weaving the cables into a new bridge surface was the responsibility of the surrounding communities. The reconstruction of the bridges was accompanied by ceremonies and offerings, and the bridge itself was sometimes considered a sacred object.

The maintenance of the tambos was the responsibility of the surrounding provinces, and the imperial state kept careful records of the supplies and labor owed to each tambo. The Spanish chroniclers recorded that the tambos were inspected periodically by officials sent from Cusco, and that the inspectors checked the condition of the buildings, the accuracy of the supply lists, and the conduct of the tambo personnel.

Historical Significance

The bridges and tambos of the Qhapaq Ñan were the operational infrastructure that made the Inca Empire possible. The Spanish, who encountered the bridges and tambos in the 1530s, recognized their importance and, in the early colonial period, continued to maintain and use them. The rope bridges, in particular, remained in use in many parts of the Andes into the twentieth and twenty-first centuries, and the tradition of annual reconstruction is still practiced in some communities of southern Peru, most famously at the village of Quehue in the Cusco region, where the Q’eswachaka bridge was inscribed on UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity in 2013 and continues to be rebuilt each year.