Roads have a very long history, Brick-paved streets were used in India as early as 3000 BC. Roads in the towns were straight and long, intersecting one another at right angles.
Only during the period of the Roman empire, roads were constructed in large scale. Many of the Roman roads were of elaborate construction. Some of these still exist after over 2000 years. The Appian Way was built in 312 BC extending over 580 KM which demonstrates the road building technique used by Romans.
Roman roads were built straight and they neglected the natural gradient. It was built after the soft soil was removed and hard strata were reached and that's why the depth of the pavement was as high as 0.75 m to 1.2 m although the load was very low. The wearing course was made of dressed large stone-blocks set in lime mortar.
The main feature of his method was that the thickness of construction need be only in the order of 30 cm. He considered the fact that drainage of water along the pavement surface and subsurface moisture content control the life of the pavement.
Tresaguet Construction (Source: Kullabs)
Telford Construction (Source: Kullabs)
Macadam Construction (Source: Kullabs)
Tresaguet Construction
In the18th century Pierre Tresaguet developed an improved method of construction of roads in France.
Telford Construction
Thomas Telford was the founder of the Institution of Civil Engineers in London. To keep the soil subgrade firm he used heavy foundation stones. He provided level subgrade of width 9m. He provided a definite cross slope for top surface by varying the thickness of the foundation stones.
Macadam Construction
John Macadam was a Scottish road builder. He was the first one to notice that the use of large stone foundation is baseless since the stress below the wheels decreases as the depth increases. He also gave importance to the subgrade drainage and compaction.
Macadam's method of construction was recognised as a scientific method of construction and hence adopted by various countries with slight modifications.
One of the most popular methods which is even now prevalent in many countries is the Water Bound Macadam (WBM) construction.
In this method broken stones of the base course and surface course, if any, are bound by the stone dust in presence of moisture. WBM roads are in use in India both as a finished pavement surface for minor roads and as a good base course for superior pavement carrying heavy traffic.
There are also bituminous bound macadam and penetration macadam which are adopted by our country.
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