THE ENGINEERING CHALLENGE Civil engineers design and build structures such as bridges buildings and tunnels Architects and engineers need to make sure the structures they design and build are strong enough to withstand forces such as high winds or shaking from earthquakes 4 The test of time The Arkadiko Bridge in Greece was built more than 3,000 years ago for use by horse-drawn chariots It formed part of a road linking the cities of Tiryns and Epidauros The stone bridge has survived the test of time and is still used today
Simple machines With no engines or electricity to help them builders in the ancient world used simple machines such as ramps and pulleys to help them lift heavy stone or wood into position Huge teams of workers were needed to do the work Today giant cranes with powerful motors do the heavy lifting work Green engineering Concerned about polluting the planet architects are designing buildings that are environmentally friendly In Singapore giant vertical gardens called supertrees have been built in a park in the center of the city They generate electricity collect rainwater and are home to a huge collection of rare plants 5 A crane lifts a huge metal beam into place as the frame of a high-rise building is constructed Read on to discover the challenges that engineers have overcome through the ages The answers to each project’s questions are found on page 31
GREAT PYRAMID OF GIZA The Great Pyramid was built in 2560 b c e At 480 feet 146 m it was the tallest of the three pyramids of Giza in Egypt and the highest building in the world for 3,800 years It is the oldest of the structures known as the Seven Wonders of the World and the only one still standing 6 A square pyramid The pyramid has a square base and four triangular sides that meet at a single point at the top This shape is called a square pyramid Before constructing the pyramid Egyptian engineers had to level the ground to within a fraction of an inch in accuracy to create a firm foundation They then began constructing the pyramid out of pre-cut blocks of stone Building blocks The Great Pyramid is made from 2 3 million separate blocks of stone each weighing about 2 5 tons 2 3 metric tons the weight of an Asian elephant Some of this stone was cut from quarries 560 miles 900 km away and transported to the building site along the Nile River The blocks were precisely carved using copper chisels to fit together along joints just 0 02 inches 0 5 mm wide
A B C The ramps may have zig-zagged up one side of the pyramid A been built inside an incomplete part of the pyramid B or spiraled on top of the structure C How was it built Historians still debate how the Great Pyramid was built It is likely that tens of thousands of workers were involved and that it took many years to complete The stones were dragged into position along ramps but we do not know how they were raised up the ramps since the Egyptians did not use wheels or pulleys Burial chambers The pyramids were built as tombs for the pharaohs kings The Great Pyramid is Pharaoh Khufu’s tomb Inside the Great Pyramid three chambers or rooms have been found a large chamber known as the King’s Chamber a smaller one known as the Queen’s Chamber and an unfinished Lower Chamber In 2017 scientists discovered a hidden passage in the pyramid What this passage was used for is still a mystery Queen’s Chamber King’s Chamber Shaft Lower chamber The Great Pyramid stands beside smaller ones Subterranean chamber 7 project RAMP IT UP The steeper a ramp is the more force you need to drag an object up Let’s investigate this further You will need a flat piece of wood some books a cup a piece of string an apple and some coins 1 Make a ramp by resting the wood on a pile of books 2 Attach the cup to the string and wrap it around the apple 3 Hang the cup over the high end of the ramp and start adding coins How many coins does it take to move the apple Change the slope of the ramp by taking some books away How many coins are needed now
