Types of Highway Construction
the highway construction types are various given below.
(1) Earth roads. (2) Gravel road
(3) Soil Stabilized Roads
(4) Water Bound Macadam (WBM) Roads
(5) Bituminous Roads
(6) Cement Concrete Roads
Construction of Earthen Roads
an earthen road is the cheapest type of road prepared from natural soil.
the pavement Section is totally made up of the soil available at site.
the maximum cross slope 1 in 2 is recommended to avoid erosion due to rain water and formation of cross ruts. the steep cross slope helps to keep the pavement surface free of standing water, otherwise the soil being previous the water would damage the pavement Section by softening.
the Construction of Earthen Roads may be divided into following steps.
(a) Construction Material
the pavement Section is totally made up of the soil available at site or nearby which is free from organic substances.
(b) Alignment Location
the centre line and road edges are marked on the ground along the road alignment by dividing wooden pegs .
the spacing of reference pegs depends on the estimated length of road Construction in a day.
(c) Preparation of Sub- Grade
the various operations involved in the Construction of sub Grade are clearing site, Excavation and Construction of soil fills to bring the road to a desired grade and shaping of sub grade.
(d) Construction of Pavement Structure
the soil is mixed, spread and rolled in Layers such that the Compacted thickness of each layer does not exceed 10 Centrimeter.
At least 95% of maximum dry density (MDD) is considered desirable
(e) Opening to traffic
The Compacted earth road is allowed to dry out for a few days before opening to traffic.
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