NECESSITY OF HIGHWAY DRAINAGE
SYSTEM: -
[1] The surface water from the
carriageway and shoulder should effectively be drained off without allowing it
to percolate to sub grade.
[2] The surface water from the
adjoining land should be prevented from entering the roadway.
[3] The side drain should have
sufficient capacity and longitudinal slope to carry away all the surface water
collected.
[4] Flow of surface water across
the road and shoulders and along slopes should not cause formation of cross
ruts or erosion.
[5] Seepage and other sources of
underground water should be drained off by the sub surface drainage system.
SURFCAE DRAINAGE: - The surface water is to be collected and then disposed off. The
water is first collected in longitudinal drains, generally in side drains and
then the water is disposed off at the nearest stream, valley or water course.
Cross drainage structures like culverts and small bridges may be necessary for
the disposal of surface water from the road side drains.
SUB SURFACE DRAINAGE: - Change in moisture content of sub grade are caused by fluctuations
in ground water table seepage flow, percolation of rain water and capillary
water and even water vapour. In sub surface drainage of highways, it is
attempted to keep the variation of moisture is sub grade soil to a minimum.
STORM WATER DRAIN: - A storm drain,storm water or simply a drain is designed to drain excess rain and
ground water from impervious surface such as paved streets, car parks, parking
lots, footpaths, sidewalks and roofs. Storm drains vary in design from small residential dry wells to large municipal system.
They are fed by street gutters on most motorways,
freeways, and other busy roads, as well as towns in areas which experience
heavy rainfall, flooding and coastal towns which experience regular storms. Even the gutters from houses and buildings can be
connected to the Storm drain.