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2. Evolution of roads

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2. Evolution of roads

  1. 1. “Necessity is the mother of invention.” By Plato  Roads and highways become one of the important part of today’s social and economical development.  But how does it come into existence?  From where did it all started?  It is interesting to know evolution of roads happened only after the development of different modes of transportation.
  2. 2.  At the earliest roads was nothing but just a trail formed by people moving on the same path repeatedly.  It can be called as footpaths. Animals were also used for carrying men and materials. The paths then formed were muddy and can be affected by changing weather.
  3. 3.  After the invention of wheel, the animals were used by the men with different carts to move or to carry things around. So, the walking trails were not enough during times of heavy rains or dry. This brought up the necessity of hard surface roads.  Such paved roads are first said to be discovered around 4000 B.C. in Mesopotamia, now known as Iraq. Those were hard and made up of stones.
  4. 4. Romans-  Romans are known as the pioneer of road construction on a large scale. They constructed about 9,000 km of length in order to move their soldiers around the country  The main characteristics of Roman Roads –  They constructed as straight as possible regardless the gradients, in order to travel as quickly as they could.  The base of roads was prepared by hard sedimentary rocks (stratum).  The second layer was prepared by pebbles and crushed stones  The next to second layer was prepared crushed stones mixed with soil.  The final or the upper layer was formed by hard paved stones.  Kerb was given to both sides of road.
  5. 5. Tresaguet Construction-  Pierre-Marie-Jerome Tresaguet (1716 – 1796) - He was a French engineer and best known for his new improved methodology for road construction. According to him it is not necessary to prepare the top with heavy stones, instead small and broken stones can be used.  The benefit of this top-layer was that it was rammed or rolled by traffic the stones jammed into one another forming a strong wear resistant surface which offered less obstruction to traffic.
  6. 6. John Metcalf  John Metcalf (1717–1810) - John Metacalf also known as Blind Jack of Knaresborough or Blind Jack Metcalf. He was responsible for the construction of about 290km of road in the northern region of England.  Metcalf realized the importance of good drainage systems beside the roads. He believed that a good must have a good drainage system, knowing it was rain that caused most problems on the roads.
  7. 7. Telford construction (1757-1834)  Thomas Telford was the founder of Institution of Civil Engineers in London.  He believed that by using heavy foundation stones above the sub grade, the road will be more firm.  He proposed to provide cross drains a intervals about 80-90 meters.  They were usually laid below foundation level as the intersects were large enough to allow the water to percolate from top to bottom of the construction and thus soften the level of sub grade.
  8. 8. MACADAM CONSTRUCTION  Macadam’s method gained recognition as the most scientific method of construction.  It was realized that the stress due to wheel load of traffic get decreased at the lower level of pavement., therefore it is not necessary to provide large stones as foundation.  Instead the sub grade was used with a cross slope of 1 in 36 to facilitate sub grade drainage.  This method became very popular. Various subsequent methods were based on Macadam’s construction are still used after his name such as water bound macadam (WBM), penetration macadam and bituminous macadam.
  9. 9. THANK YOU

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