MU

1. DRAINAGE OF PAVEMENT
AND WATER PERCOLATION
Arsalan Jamal
Nipunna Raj Poudel
Dipesh Kafle
Amit Yadav

2. DRAINAGE OF PAVEMNT
 Surface drainage is concerned with removing all water that is present
on the pavement surface, shoulder surface or any other surface from
which it may flow onto the pavement. If not systematically removed,
this water can accumulate underneath and weaken the pavement
structure.
 The three principal types of highway drainage are:
 Surface drainage.
 Subsurface drainage.
 Cross drainage


3. .
 Dewatering” consists of following elements:
 – Cross fall
 – Road shoulders
 – Impermeable road surface materials
 A typical “drainage” system consists of following elements:
 – Outlet ditches
 – Side ditches
 – Culverts
 – Inner/outer slopes
 – Road structures
 – Underdrains

4.  4.3 Side ditches
 Side ditches collect road water and lead it onward to outlet ditches
are especially important when road is in cut. If the road is on a high
embankment, side ditches are not always necessary and their need
to be evaluated case by case.

5. DRAINAGE STRUCTURE SIZING
Steep slopes Bare, light
vegetation
Gentle slopes Heavy
vegetation
Drainage
area
(Hectares)
Round pipe
Ø (m)
Area (m2)
Round pipe
Ø (m)
Area (m2)
0..4 0.76 0.46 0.46 0.17
4..8 1.07 0.89 0.61 0.29
8..15 1.22 1.17 0.76 0.46
15..30 1.83 2.61 1.07 0.89
30..50 2.13 3.58 1.22 1.17
50..80 2.44 4.67 1.52 1.82
80..120 1.83 2.61
120..180 2.13 3.58

6. WATER PERCOLATION
 Percolation is the downward flow or seepage of water through the
pores of rocks and soil. AS the water percolates into the deeper layers
of the soil, it reaches ground water, which water below the surface. The
upper surface of this underground water is called “Water Table”.
 Example: Permeable pavement system allows percolation of rainfall
water. Interconnected void spaces in the pavement allow storm water
to filter through the soil below the paved surface, reducing the
numerous environmental issues associated with water runoff.

7. METHODOLOGY
The methodology contains
recommendations and requirements
for designing, performing, and
maintenance of drainage system on
road and bridge structures.

8. The slope of the pavement is crucial to keep water from pooling on
the surface of the pavement. A pavement with little to know
drainage slope will quickly develop many puddles (future potholes).
Bituminous roadways recommends constructing new pavements ,
with at least 1%slope.for existing pavements, routine maintenance is
crucial to protect pavements from water damage.

9. CAMBER
 We have seen almost all highways being raised in the middle portion of the road surface with respect to the edges. This cross slope in the
transverse direction is called as the Camber (or Cant). It is generally provided with the sole purpose of draining the rain water from the road
surface towards the edges.
 Other objectives of providing camber are:
 Protection of the road surface, especially for gravel and bituminous roads by draining the unwanted water as quickly as possible.
 Protection of the subgrade by providing good drainage conditions.
 For safety considerations, as wet pavement conditions are quite undesirable from safe driving point of view.
 The cross-section shape of the transverse or cross slope can be curved, straight or a combination of both. The central part of the road which is
raised is called the crown.
 The cross slopes can be expressed in slope as 1 in n or in percentages as n% (for example, 1 in 50 or 2%). The design values of cambers mainly
depend upon the type of the pavement and also on the average amount of the rainfall in the area. Steep cambers are effective in quick removal
of surface water but are undesirable as they will erode the surface. Generally, cambers of slope 2 to 3% are provided. On straight sections of
roads, shoulders are provided with higher cross fall than that of the carriageway by 0.5%.

10. A

11. THANK YOU