History of road development can be studied under the following headings:
1.History of the road in Early Development stage( Early Development)
The oldest mode of travel was on the footpath. Animals were widely used to transport men & materials. Later -an invention of wheels leads to the development of vehicles run by the help of animals. This type of vehicles becomes the most popular mode of transportation for a very long period of time.
2. Roman Roads
These are the development of the road by the Roman civilization some are still in existence.
Roman roads were up elaborate construction built with stones block of considerable thickness.
The main features of the Roman road are:
-They were built straight reagents of gradients (Slope).
-They were built after soft soil is removed and a hard status was reached.
-The total thickness of the construction was as height as 0.75 m to 1.2 m.
fig: 2300 years old road in Itlay
3.Tresaguet Construction :
After the fall of the Roman empire, their technique of Road construction didn’t gain popularity in other countries.
Development & improved method of construction in France by the year 1964 AD.
Pierre Trezeguet (1716 – 1796 AD) developed several methods of construction which were considered to be quiet advantageous meritorious.
The main features of his proposal were that the thickness of construction needs to be only in the order of 30 cm.
Besides due consideration was given to subgrade moisture condition & drainage of surface water.
4. Metcalf Construction:
John Metcalf 1717-1810 was engaged in road construction in England during the period when Trezeguet was working in France.
He apparently followed the recommendations made by Robert Phillips.
Metcalf was responsible for the construction of 290 km of road in northern England.
Thomas Telford 1751 – 1834 AD founder of the institution of civil engineers at London began the world of road construction in the early 19 century.
He believed in using a heavy foundation above the soil subgrade to keep the road foundation formed also insisted on providing definite cross slope for the top surface of the pavement by varying the thickness of foundation on stones.
He proposed to provide cross drains at an interval of almost of 90m which were usually laid below the foundation level.
There are different stages of road development. But among all of them, Macadam road is the most successful type of road. Some detail features about macadam road are:
-John Macadam 1756 -1836 AD was the surveyor of general of a road in England who put forward an entirely new method of road construction.
-The macadam method is the first method based on scientific thinking.
-It realized that the stresses due to wheel load get decrease at the lower layers & so it is not necessary to provide large layer pavement.
-The importance of subgrade drainage and compaction was recognized so the subgrade was compacted and was prepared with across slope (1 in 36 ).
There are four types of Macadam roads and they are:
a. Water Bound Macadam
In this type, broken stones are bounded with the help of stone dust and water during the construction process.
b.Traffic Bound Macadam
Broken stones or gravels are generally used as a wearing. Multi-layers of stones and gravels are provided in this type.
Bitumen is used as a binding material to bind stone chips and also to bind base and sub-base courses.
d. Cement Macadam
Cement macadam is quite similar to bitumen macadam. Cement is used as a binding material instead of bitumen.