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Monday, January 30, 2017

PROJECT REPORT ON HIGHWAY DRAINAGE SYSTEM


Project Report
On
“Highway Drainage System”



Submitted By
Mr. Manoj Kumar
Civil Engineer


Abstract


This project attempts to design an efficient, economic and easy-to-maintain “Drainage System” for the road construction.


It is also necessary because the installation of suitable surface and sub-surface drainage system is an essential part of highway design and construction.



                                                                                                                                 Contents
Sr. No.

Contents

Page No.

1

Introduction
1

1.1
Historical Background
1

1.2
Problem Statement
1

1.3
Objectives
2
2

Literature review
3

2.1
Introduction
3

2.2
Types of Drainage
3

2.3
Measures Adopted For Surface Drainage

5

2.4
Collection Of Surface Water


5

2.5
Classification Of Side Drainage

5

2.6
Requirement Of Highway Drainage System
6

2.7
Design Of Surface Drainage

6

2.8
Hydraulic Design

7
3

Data Analysis
10

3.1
Rainfall Data
10

3.2
Data Representation
11

3.3
Determination of Runoff

12

3.4
Peak design Flow
12
4

Design of New Side Drainage
14

4.1
Design For Trapezoidal section


14

4.2
Design for Rectangular section
17
5


Conclusion & Recommendation
19
6


References
  
20
















































1. Introduction
         Drainage is the process of interception and removal of water from over, and under the vicinity of the road surface. Drainage can be surface (where water is conveyed on the road surface and drainage channels) or sub-surface (water flows underneath the pavement structure).

Surface and sub-surface drainage of roads critically affects their structural integrity, life and safety to users and is thus important during highway design and construction. Road designs therefore have to provide efficient means for removal of this water; hence the need for road drainage designs.
Drainage facilities are required to protect the road against damage from surface and sub-surface water. Traffic safety is also important as poor drainage can result in dangerous conditions like hydroplaning. Poor drainage can also compromise the structural integrity and life of a pavement. Drainage systems combine various natural and man-made facilities e.g. ditch, pipes, culverts, curbs to convey this water safely.
1.1.         Historical Background:

This road is located along “G.T. Highway” in Sikandrabad, Bulandshahr, Uttar Pradesh. It is unpaved road and is under the Sikandrabad Municipal Council.

1.2     Problem Statement:
According to this problem of lacking side drainage along this road, the soil surrounding the GT Highway fence has been eroded by the water flowing during the rain, also because the water during the rain is passing on the road, potholes has occurred on top of this road.
Therefore a drainage system has to be designed. However, the existing road along this street is showing signs of failure, caused mainly by lacking of drainage. Also it is better to have good method of designing a side drainage in order to overcome these problems arises on this road.


1.3    Objectives:
Main objective:
To design an efficient Drainage System along this road.
Specific Objectives:
Ø To determine the catchment area and the expected flow.
Ø To collect design information for drainage system.
Ø To determination of runoff onto the road and discharge of water.
Ø To design of the drainage channels using results obtained.
Scope of the project:
This project is confined only to designing a drainage system for the road along the road.
Significance of the project:
The outcome of this project shall help to propose the lay out for the new side drainage in order to fulfill its requirements as a drainage, such as to drain off excess water on shoulder and pavement edge which cause considerable damage and improve pedestrian safety using side walk ways near side drainage.
 Methodology:
Ø Site visiting
Ø Visiting web sites and Internet
Ø Literature review
Ø Questionnaire method
Ø Photographing
Ø Leveling 


2.0           Literature Review

2.1            Introduction:
                              
        Highway drainage is the process of interception and removal of water from over, under and in the vicinity of the pavement.

Highway drainage is one of the most important factors in road design and construction. If every other aspect of the highway design and construction is done well but drainage is not, the road will quickly fail in use due to ingress of water into the pavement and its base.

The damaging effects of water in the pavement can be controlled by keeping water out of places where it can cause damage or by rapidly and safely removing it by drainage methods.

Improper drainage of roads can lead to:-

Ø Loss of strength of pavement materials
Ø Hydroplaning
Ø Mud pumping in rigid pavement

Ø Stripping off the bituminous s surface in flexible pavements

2.1               Types of Drainage:



2.1.1    Sub-Surface Drainage

Subsurface drainage is concerned with the interception and removal of water from within the pavement. Some of the sources of subsurface water include; infiltration through surface cracks, capillary rise from lower layers, seepage from the sides of the pavement to mention but a few.

Application of side slopes on the road surface, installing of drainage beds in the pavement and use of transverse drains are some of the measures of effecting subsurface drainage.

2.1.2    Surface Drainage

Surface drainage deals with arrangements for quickly and effectively leading away the water that collects on the surface of the pavement, shoulders, slopes of embankments, cuts and the land adjoining the highway. 

The main source of surface water in most places is precipitation in form of rain. When precipitation falls on an area, some of the water infiltrates in to the ground while a considerable amount remains on top of the surface as surface run off.

2.1.3    Cross Drainage

When stream have to cross a roadway or when water from a side drainage have to be diverted to water course across the roadway, then a cross drainage work such as culvert or small bridge is provided.

On less important roads, in order to reduce the construction cost of drainage structures, sometimes submersible bridges or course way are constructed. During the flood the water will flow over the road



2.2            Measures Adopted For Surface Drainage

Ø The proper cross slope should be provided for both to pavement and shoulders
Ø The subgrade should be sufficiently above the highest level of ground water table or the natural ground level
Ø Side drainage should have to be provided at edges of right-of-way where the road is in embankment and the edge of the roadway in cutting
Ø On hill roads, water may flow towards the road depending on the slope and rainfall
Ø Catch water drains should be provided to intercept the flow down.

2.3            Collection Of Surface Water

The water collected is lead into natural channels or artificial channels so that it does not interfere with the proper functioning of any part of the highway.

Surface drainage must be provided to drain the precipitation away from the pavement structure.


                                         2.4            Classification Of Side Drainage




2.6 Requirement of Highway Drainage System

Ø The surface water from the carriage way and shoulder should effectively be drained off without allowing it to percolate to sub grade
Ø The surface water from the adjoining land should be prevented from entering the roadway.
Ø The surface drainage should have sufficient capacity and longitudinal slope to carry away all the surface water collected.
Ø Flow of surface water across the road and shoulders and along slopes should not cause formation of erosion.

2.7  Design Of Surface Drainage

Ø  Hydrological analysis
Ø  Hydraulic analysis


2.7.1      Hydrological analysis

This deals mainly with precipitation and runoff in the area of interest. When rainfall, which is the main source of water, falls onto an area some of the water infiltrates into the soil while the remaining portion either evaporates or runs off.

The portion that remains as runoff is the one of major importance in the design of surface drainage facilities.

2.7.2     Determination of runoff

Runoff at a particular point is determined with respect to a given catchment area and depends on a number of factors such; type and condition of the soil in the catchment, kind and extent of vegetation or cultivation, length and steepness of the slopes and the developments on the area among others.

The following formula known as the rational formula is used for calculation of runoff water for highway drainage.
        
Q = 0.028*C*I*A 




Where:
            Q = maximum runoff in m3 per sec
            C = runoff coefficient depending upon the nature of the surface
             I = the critical intensity of storm in mm per hour occurring                                   during the time of concentration.
            A = the catchment area in km2
                     
2.8 Hydraulic Design

Once the design runoff  Q is determined, the next is the hydraulic design of drains. The side drainage and other structures are designed based on the principles of flow through open channels.

If Q is the quantity of surface water (m3/sec) to be removed by a side drainage and V is allowable velocity of flow (m/s) on the side drainage, the area of cross section A of the channel (m2) is found from the relation below:
Q=A*V                                              
                                                     

The velocity of unlined channel must be high enough to prevent silting and it should not be too high as to cause erosion. The allowable velocity should be greater than one (1m/sec) for lined channel.

The slope S of the longitudinal drain of known or assumed cross section and depth of flow, may determined by using Manning’s formula for the design value of velocity of flow V, roughness coefficient n and hydraulic radius R.


Manning’s Formula

 V={1/n}*R2/3*S1/2


              
Where:
              V = Average velocity m/sec
              n = Manning’s roughness coefficient
              R = Hydraulic radius
              S = Longitudinal slope of channel.




Manning’s Roughness coefficient

              n = 0.02 for unlined ordinary ditches
                 = 0.05 to 0.1 for unlined ditches with heavy vegetation
                 = 0.013 for rough rubble
                 = 0.04 for stone riprap
                 = 0.015 for pipe culverts

Hydraulic Radius


Hydraulic radius  =   [Cross sectional area]
                                   [Wetted perimeter]

Time of concentration (Tc)

Time of concentration is that time required for water to travel all al the way from catchments area to the designed element.

The time taken by water to flow along the longitudinal drain is determined from the length of the longitudinal drain L of the nearest cross drainage or a water course and allowable velocity of the flow V in the drain.
T = V/L



The total time for inlet flow and flow along the drain is taken as Time of concentration or the design value of rain fall duration.
Tc   = T1 + T2
                              
                               
               
  Where,
                                T1 = overland flow time in minute

                                T2 = is channel flow time in minute
 

T1 =[0.885(L)3/H]0.385
                             

Where,
                       L = the length of overland flow in km from critical point of the mouth of the drain.                                      .
                        H = total fall of level from the critical point to the mouth of the drain in meters.
   
Note: -    From the rainfall intensity –duration- frequency curves the rainfall I is found in mm/sec. Corresponding to duration T and frequency of return period.

The required depth of flow in the drain is calculated for convenient bottom width and side slope of drain. The actual depth of the open channel drain may be increased slightly to give a free body. The hydraulic mean radius of flow R is determined.

The required longitudinal slope S of the drain is calculated using Manning formula adopting suitable value of roughness coefficient. 


2.0           Data Analysis

2.1            Rainfall Data

The following are the rainfall data in Sikandrabad, which obtained from the Hydrological Department. The data are of 11 years from 2000 to 2010 {in mm/hr}.

Maximum Rainfall Intensity Duration Frequency Data In One Day Per Year (mm/Hour)

YEAR
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
2000
28.2
26.7
44.6
143.8
30.1
10.5
3.8
15.8
3.9
1.0
102.6
120.7
2001
225.1
23.5
179.1
108.5
47.7
16.9
1.0
3.0
0.4
0.2
43.3
55.7
2002
124.8
136.3
151.6
220.3
103.8
7.6
1.6
15.8
43.0
97.8
36.8
131.9
2003
33.0
49.2
53.0
39.4
128.3
14.3
2.8
0.1
7.3
23.0
18.1
76.2
2004
79.6
75.9
52.8
97.6
10.5
10.2
0.5
1.0
7.3
30.9
28.3
80.4
2005
14.0
13.2
120.9
130.1
68.5
6.8
3.1
2.2
2.9
58.7
86.5
23.1
2006
36.5
79.4
214.1
291.7
117.9
17.6
7.2
3.7
41.0
58.4
186.9
186.2
2007
70.2
26.0
150.2
112.3
94.0
8.2
4.3
36.1
12.4
21.4
59.5
79.9
2008
27.6
77.7
3.1
2.3
22.6
6.3
4.4
1.2
4.2
0.0
84.2
20.2
2009
47.0
47.6
36.1
123.8
49.7
6.4

0.0
0.0
52.9
144.9
128.5
2010
83.6
106.2
95.9
314.3
49.7
1.3
6.3
0.8
3.0
0.8
11.6
78.0
Maximum Monthly Rainfall



2.1            Data Presentation

In case of this road, open side drain of trapezoidal and rectangular have to be provided for disposing of surface water collected. The first step will be to estimate the amount of surface water flowing, the amount of surface water depend upon the intensity of rainfall, amount of rainfall, nature of the soil and topographical of the area. Therefore the quantity of water that can be handled by this ditch or drain can be estimated.


Year
Maximum rainfall per month (mm)
2000
143.8
2001
225.1
2002
220.3
2003
128.3
2004
80.4
2005
130.1
2006
291.7
2007
150.2
2008
84.2
2009
144.9
2010
314.3

 

From the graph the maximum rainfall intensity in the given years (2000-2010) is 314.3mm/hr.

2.2      Determination of Runoff

Run off at a particular point is determined with respect to a given catchment area and depends on a number of factors such as type and condition of the soil, kind and extent of vegetation (cultivation), length and steepness of the slope and development of the area among the others.

2.3            Peak Design Flow

This is the maximum flow rate of a flood wave passing a point along a stream. As the wave passes the point, its flow increases to the maximum and recedes. It is a major factor in culvert designs, and its magnitude is dependent on the section of the return period.

Catchment Areas (Area Data)

v Unpaved gravel road surface and shoulders:
Length of the area=0.685km
Width of the area=0.008km
Area = Length*Width
= 0.685*0.008
= 0.00548km2

v Area of land on the other side drain:
(Build up area) = 0.021*0.8
                                            = 0.02km2

v Area covered with grass:
= 0.0234*0.214
= 0.005km2

v Total catchment area (A) = 0.03km2

           
 Surface runoff coefficient (C)

Ø Coefficient of gravel surface=0.35
Ø Coefficient of build up=0.8
Ø Coefficient of soil covered with grass=0.1
Therefore C1=0.35, C2=0.8, C3=0.1

Weighted value of runoff Coefficient:

C = {C1A1 + C2A2 + C3A3}/{A1 + A2 + A3}


    = {0.35*0.00548 + 0.8*0.02 + 0.1*0.005}/{0.00548 + 0.02 + 0.005}= 0.614 

Therefore the runoff coefficient (C) =0.614

Peak flow (Q)

From the formula :         Q=0.278*C*I*A

Where: 
                    Q= Quantity of rain water surface runoff in m3/sec
                    C= Surface runoff coefficient
                    I= Maximum rainfall intensity in mm/hour
                    A= Size of surface area to be drained in km2

     Now,      C= 0.614
                    I= 314.3 mm/hour
                    A= 0.03km2
                     
  Q= {0.278 * 0.614 * 314.3 * 0.030 * 106}/{60 * 60}
 Q= 0.447m3/sec

Therefore, Quantity of rain water surface runoff (Q) = 0.447 m3/sec

4.0  Design of New Side Drainage

4.1 Design For Trapezoidal section

Cross section area (A) of the side drainage required will be obtained from the formula below;
             Q = A*V
Where;
             Q = Quantity of rain water surface runoff in m3/sec
             A = Cross section area in m2
             V = Velocity of flow in m/sec
Now we have
             Q = 0.447m3/sec
             V = 1.5m/sec for lined structure
             A =?
Therefore,
             A = Q/V
             A = 0.447/1.5
             A = 0.298m2
Therefore, the required cross section area is 0.298m2
 Consider the trapezoidal section below:
f=free water body=150mm

Required Dimensions:

Ø Suppose the bottom width (b) =0.5m
Ø Side slope (S) =1:1
Ø Free water body = 0.15m
Ø Vertical height (d) =?
Ø Horizontal length (B1) =?

From the formula
                  Area = 0.5*(B1 + b)*d
                
                  Area (A) = 0.298m2
                  B1 = 2d+0.5m
                  b = 0.5m
                  d =?
                
                  0.298 = 0.5*(2d + 0.5+ 0.5)*d
                  0.298 =0.5 (2d + 1)*d
                  d2 +0.5 d-0.298 = 0
                  d = 0.35m
             
                  B = (2* 0.35) + 0.5 =1.2m
                  D = (0.35+0.15) = 0.5m

   Wetted perimeter is equal to the total length of the wetted area
                = Length of two side slope + Bottom length
Where Bottom length = 0.5m

         And Length of side slope is calculated below
From Pythagoras theorem,

S2 = d2+d2
S = (0.352+0.352)1/2
S = 0.495m
Wetted perimeter = 0.495+0.495+0.5
                             = 1.49m
Longitudinal slope

From Manning’s formula
         V = 1/n*R2/3*S1/2


And therefore         S = (n*V/R2/3)2

Where;
             S = Longitudinal slope
             V = Velocity of flow in m/sec
             R = Hydraulic Radius
             n = Manning’s roughness coefficient

Hydraulic Radius = Cross section area ÷ Wetted perimeter
               
                R = 0.298 ÷ 1.49
                R = 0.2m
                n = 0.04
                V = 1.5m/sec

S = [0.04*1.5 / (0.2)2/3]2
S = 0.0307

Therefore, the proposed slope for the side drainage is 0.0307

4.2 Design for rectangular section

From the formula

          Q = A* V

Where Q, A and V are already defined before
            Q = 0.447m3/sec
            V = 1.5m/sec
            A = ?

Q = A*V
0.447 = A*1.5
A = 0.298m2

Required dimension

Ø Suppose the bottom width = 1.2m
Ø Free water body = 0.15m
Ø Vertical height =?
Consider the formula of rectangular section:
      Area (A) =Height * Width
      
      Now, Height (d) =?
      Width (b) =1.2m
      Area = 0.298m2

0.298 = 1.2*d
d =0.25m
      D =0.25 + 0.15m
      D =0.4m


Longitudinal slope is also calculated from the Manning’s formula:

         V = 1/n*R(2/3)*S(1/2)

         R =               Area  divided by Wetted Perimeter


Wetted perimeter = (1.2*2) + (0.25*2) = 2.9
        
R =      0.298/2.9

R = 0.103,
n =0.04,
V =1.5m/sec

Now by S = (n*V/R2/3)2

S = {0.04*1.5/0.1032/3}2
S = 0.0745

5.0 Conclusion

After this research many problems were discovered such as potholes, corrugations, water lodging, ruts ,erosion on the edge of the road as the result of inspection, practical checking of the whole road and all areas surrounding the road.

In order to maintain the life span and purpose of the road as designing Road side drainage of adequate size and capacity, the discharge and all dimensions produced can be used for the construction as it designed.



Recommendation

Since the condition of the drainage along G.T. Road is not satisfactory, therefore this problem must be taken into consideration together with the information gathered on the road conditions.


6.0           References

[1] IRC, “Road Drainage Practice  Around The World”, Special publication, Indian Road Congress.

[2] Luthin J.N., “Drainage Engineering”, Wiley Eastern (P) Ltd.

[3] DSIR, “Soil Mechanics for Road Engineers” HMSO London.

[4] Khanna S.K, “Highway Engineering”, Nem Chand & Brothers.

[5] Cedergren, H.R., “Design of Highway & Airfield Pavements”, John Willey & Sons.


Appendices
1.    Booking Sheet For Leveling
BS
IS
FS
RISE
FALL
RL
REMARKS
0.08
BM 0.080
0.235
0.08
0+000
1.16
0.925
0.845
0+030
1.372
0.212
0.633
0+060
1.465
0.093
0.54
0+090
1.71
0.245
0+120
0.71
0+120
1.173
0.463
0+150
1.513
0.34
0+180
2.169
0.656
0+210
0.115
0+210
0.989
0.874
0+240
1.825
0.836
0+270
2.621
0.796
0+300
3.3
0.679
0+330
0.249
0+330
2.179
1.93
0+360
0.949
0.933
0+360
1.882
0+390
3.349
1.467
0+420
0.12
0+420
1.687
1.567
0+450
3.232
1.545
0+480
0.232
0+480
1.559
1.327
0+510
2.323
0.764
0+540
2.87
0.547
0+570
3.672
0.802
0+600
1.295
0+600
1.773
0.478
0+630