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Inca roads were built without the benefit of sophisticated surveying equipment using only wooden, stone, and bronze tools. However, those ancient engineers paid special attention to environmental conditions.
The constructions were built with seismic events in mind and that's what engineers today are excited to study - how we can benefit from that knowledge.
Sustainability was the key to success. The Incas paid attention to local conditions, using local materials and working with the landscape.
On steep terrain they built steps to dissipate the water's energy and counter erosion. At high altitudes they paved the way with local stone to protect the surface from ice and snow melt, and when they needed supporting walls they left holes for the water to drain.Today, earthquakes, landslides, floods destroy so many roads because modern day engineers use sophisticated equipments but fail to consider these environmental factors. Modern day engineers then ought to spend more time planning for drainage and sustainability of the modern day roads.
Please let me know if you need any clarification. I'm always happy to answer your questions.
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