Andean Archeology the suspension bridges technology of the Incas
However, their culture has continued to influence various aspects of the world today especially in Europe. They existed in the in the Andean mountains areas area which is the modern day Peru. Their capital was in Cusco and was strategic in administration of the empire. The Inca referred to their empire as Tawantinsuyo meaning the four regions (Bauer, 4). The Inca people did conquered and assimilate other areas such that the empire covered an exclusive part of South America. Quechua was their official language but there also were other local languages and dialects used. Though their origin is not clearly known, the history of the Inca people has been quantitatively and qualitatively recorded through stone, silver, gold, tapestry, jewelry and oral tradition (McEwan et al, 288).
Having gained control over a relatively large territory in the Americas mountainous south, the Inca people were prompted to build reliable road networks to connect the various parts of the territory. The hilly topography of this region was a challenge to the ease of administration over this region.
According to Ciezo de Leon, the terrain of this region was formidable and required a road system that would pass through snow, over mountains, quagmires, turbulent rivers, living rock and deep valleys (Bauer, 472). This is because effective and reliable means of communication could not be easily developed. This prompted the Incas people to employ their highly advanced technology to develop reliable road network to connect various regions and enhance movement of both people and goods. The idea of a road network initiated the idea of suspension bridges to connect roads from one ridge or bank to another. This was a mile stone in the history of Inca since through the suspension bridges the issue of communication and transport among the various regions had been made successful (McEwan, 289). The Incas had great architectural skills and engineering ability, which they employed to build suspension bridges. This facilitated the development of the all-weather road network. The suspension bridges were the core elements in connecting the various road networks such that the whole of the Americas south pacific coast was in turn connected (Bauer, 474). This saw the connection of close to 14,000 miles of roads in Inca and this became the most inspiring and reliable precursor to the development of the automobile industry in Peru. Cusco could then communicate and link easily and effectively with both the lowland desert and mountain dwellers. Technological advancement leading to the advent of the suspension bridges led to the transportation of materials and as well as aiding in movement of ceremonial processions. This influenced to great extents the civilization of other communities.
As the wheel had not yet been discovered during this civilization, the Inca would travel on foot or use llamas. Thus, suspension bridges were vital in crossing rivers, connecting ridges, valleys. As Brian (468), notes, If only one of their hundreds of bridges was damaged, a major road could not fully function... These innumerable bridges were constructed using grass and also made use of other aspects of the Inca culture such weaving. The bridges were the most inspiring engineering achievement of the pre-industrial period (Brian 475). In occasions necessitating very large bridges such as the Urubamba river suspension bridge near Ollantaytambo, a central reinforcement to the bridge was built in the rivers middle to link the two valleys or banks being connected. The length of a bridge would determine the extent of features that would be incorporated on a bridge for guaranteed functioning (McEwan et al, 290). For instance, the large bridges would have site platforms built on the riverbanks to serve a number of factors. Such platforms provided anchorage to the cables of the suspension bridges and most importantly enhanced the strength of the bridges by reducing the distance of span of the bridges. The platforms also ensured the safety of the people and llamas using the suspension bridges due to the stableness enhanced by the platforms. This is because people could enter the swinging bridge safely than without the platforms.
Stone towers were a common feature on the sites of the bridges. The towers were the base for the bridges as they were use to suspend the side cables. The towers were built carefully strong as they were the, main support of both the bridge and the users. Due to the great engineering skills and architectural designs employed on the bridges, many colonial chronicles on the Inca Empire have focused on these bridges (Brian 476). Governments of Spain and Andean nations also have a lot documented on these bridges. Due to their importance, a number of these bridges are in use up to this date while other has been improved. According to Garcilaso de Vega, (an early Peru chronicle by the Spanish), the bridge building process would begin with the cutting of adequate plant cable weaving material (Brian 78). These materials would vary from wild grasses to willow depending on the availability and the local environment. Following the collection of the materials, cables were made by braiding. Plaiting of twines would result into small cords that were the major cords braided together to make a cable. The number of cords used would be determined by the size of the cable needed which would in turn be dependent on the bridge strength required. The cables were made to measure between one and two feet in thickness (McEwan et al 293).
Once the cables were ready, the actual work of building the bridges would begin. A raft would be sued to take the cable to the opposite bank after which the rest of the larger cables would be pulled along. This work would usually involve a number of people as the cables were heavy and would require fastening on the towers and rocks. Other two cables would be connected between the two towers to provide balance to the traveler due to the undulating nature of the bridge (McEwan 297).
The walkways would be drawn at ground level across the towers. Larger suspension bridges would encompass the use of wooden branches which were laid perpendicular to the larger cables. These ensured that the walkway was wide enough and safe for the travelers. According to Pedo Sancho, balancing skills were paramount while crossing the bridges as they swung so much (Brian 480).
After the arrival of the Spaniards.
Having been much civilized, the Spaniards brought with them sophisticated technology that had a great impact on the suspension bridges of the Incas. However, the Spaniards noted the importance of the suspension bridges and thus did not abolish them once they gained control over the Inca (Brian 483). Rather, these bridges lasted for centuries while others were improved. According to Gade, the fiber bridges were in some regions replaced with stone arched bridges. The stone arched bridges were not as durable though due to destruction by floods and were also expensive to build. The vital role played by the bridges was to connect the capital Cusco to the rest of Andes. Some key bridges were improved to enhance movement. For instance, the 1564 stone bridge close to Abancay has existed to this day as a single span bridge. Continued interaction with the technology from Europe continued to bring changes or improvements in this technology. This was specifically enhanced by the availability of iron in the 19th century. Iron gradually replaced the leed fiber cables and the bridge form also changed. The bridges first were made using chains and later iron cables (McEwan 297). Making bridges using iron was easier as iron cables could be tightened to enable construction of flat walkways on the bridge. Iron bridges were efficient as they could handle more weight than the fiber cables and were also safer than the fiber cables. By the 19th century, iron bridges had almost entirely replaced the fiber ones and leather had replaced the fiber cords for suspending the bridges (Brian 485).
By the middle of the 20th century, the use of automobiles grew in central Andes bringing about rapid changes in the road and bridge networks that spread to the south. Modern roads were built of less steep areas where it was essay to develop roads. Despite the presence for modern engineers and technological advancement, it was not possible to face out the Incas suspension bridges. In areas where only foot traffic was possible, the bridges remained very vital (Brian 487). However in the 1925s, highway construction in the Andean area was at peak and this had an immense influence on the bridge system. Steel was used in the construction of bridges. Simple truss beams were used in building the bridges that would accommodate cars and trucks. The involvement of the local Inca people in bridge making at this time declined as the decisions regarding the construction of the bridges were made at the Spanish departments for public works (McEwan 295).
The modern world suspension bridge technology borrows a lot from the Incas technology. This technology has been incorporated into bridge construction works in most parts of Europe today. This has opened up remote and other areas unreachable by road system and as a result enhanced interaction and utilization of resources. For instance, the Spaniards were able to effectively use this technology to build their own bridges to reach areas they had interest in. in modern Europe for instance, stressed ribbons are used to construct bridges basing on Incan principles. As Brian (491) notes,
The first stress ribbon design pedestrian bridge that was built in the United States, in 1990 in Redding, CA is easily identified as a modern version of the Inca suspension bridge form.
Its undeniable that the suspension bridge technology did and continues to significantly contribute to the transport and communication industry.
Categories:
0 comments:
Post a Comment