Road Drainage

The objective of road drainage may be broadly classified as:

-Prevention of accumulated surface water on or by the roadway and flowing onto the roadway.

-Interception of groundwater from entering the road structure from beneath.

-Prevention of abrasion of the roadway edges, drains, embankment slopes, cut slopes and therefore the roadside itself.

-Conveying river and stream water across the roadway in an appropriate manner.

Requirements Of Road Drainage

-Camber.

-Gradient.

-Cross drainage work.

-Side drains.

-Intercepting drain – just in case of hill road.

-Water table.

-Highest flood level.

-Adjoining land.

(a)Camber and shoulder:

The surface water from the carriageway and shoulder should effectively be drained off without allowing it to percolate to subgrade and weaken the soil.

(b)Adjoining land:

The surface water from the adjoining land should be prevented from entering the roadway.

(c)Side drains:

The side drain should have sufficient capacity and longitudinal slope to hold away all the surface water collected from the roadway.

(d)Intercepting drain:

Seepage and other sources of underground water should be effectively intercepted and drained off by an acceptable subsurface system.

(e)Water table and sub-surface drainage:

The highest level of the groundwater
the table should be kept well below the extent of the subgrade, preferably by a minimum of 1.2m. If the best level geological formation is closer than 1.12m, it's desirable to lower the identical with a well-planned and laid subsurface system.

(f)Special precaution for water-logged areas:

In water-logged areas, special precautions should be taken, especially if detrimental salts are present or if flooding is probably going to occur.