Highway design raport(final) (group 2)

Highway Design Senior Project 2010

Part- I

Section-1: Introduction

There is a growing universal demand for well prepared professionals in all disciplines. In
addition, increased pressure has consequently been placed in educational institution to prepare
the required number of qualified professional to fulfill society’s need. It is imperative that there
is a large need in the industry for engineers with training and experience, and the academic
should move successfully to fill the need. This is especially true for in the situation of Ethiopia
where there is a lack of well trained and experienced urban engineer’s.

Therefore, the integration of academic program and exposing students to more practical project
results in well-seasoned and, well-educated professionals.

Thus, this high way design project is intended to equip the students with practical design
reinforcing what they have attained theoretically in the class.

It is already known that, for rapid economic, industrial and cultural growth of any country, a
good system of transportation is very essential. One of the transportation systems that are
economical for developing countries like Ethiopia is road. A well – designed road network plays
an important role in transporting people and other industrial products to any direction with in
short time. Roads, to satisfy their intended purpose, must be constructed to be safe, easy,
economical, environmentally friend and must full fill the needs of inhabitants. Being safe, the
number of accidents that can occur will be minimized. Easiness decreases operation cost,
pollution and even time cost. Economical roads assure their feasibility according to their plans
and initiate further construction of roads. Schemes that do not satisfy the needs of localities may
not get the maximum utilization of the surplus man power that is really to exist in the rural
community and also its economical value may also decrease. Therefore, from this project it is
expected to understand and to get acquainted with the above facts by going through on the
following design aspects.

1.1 General Background

1

ECSC, IUDS, Urban Engineering Department (UE)


This high way design project is taken from the Hargele - Afder – Bare - Yet road project, which
is located in the Eastern part of the country in Somali National Regional State, Afder
Administrative Zone, Afder and Bare Woredas. The project is intended to facilitate the existing
and for the expected traffic load in the future, because the town is developing.

From this road we have given a stretch of 3 km emanating from station 12+500 to 15+500 for
this project to do geometric and pavement design in general.

1.2 Objectives

This final year design project on high-way has the following major objectives:-

 To expose the prospective graduates to a detail and organized design on road projects;
 To implement the knowledge that the prospective graduates have learned theoretically in
classes;
 To ensure a good carrier development;

1.3 Brief Description of The Project Area

The Hargele - Afder – Bare - Yet road project, is located in the Eastern part of the country in
Somali National Regional State, Afder Administrative Zone, Afder and Bare Woredas. The
project starts at Hargele (5º13’N and 42º 11’E) and pass through Hargele, Afder, Bare, town and
ends at Yet. The project length is estimated to be 142.4km. The Location map together with the
topographic map of the project area is shown below.

Fig. 1.1 Project Location Map

2



Location of the Project Road

Fig. 1.3.3 Digitized Proposed Project Alternative Alignments

3



Climate:

One of the environmental factors that affect performance of pavements structures is climate.
Hence, climate data of the project area mainly rainfall intensity, in terms of mean monthly and
mean annual and, temperature are required. According to the map shown on National Atlas of
Ethiopian Atlas, the project area is located in the region of the lowest annual rainfall. The mean
annual rainfall in this region is 300mm per year. The rainfall of the project area is characterized
by the following rainfall distribution:

 April, May and October  The wettest Months
 And in the remaining months  The driest months.

Topography:

The terrain of the project area through which the road alignment traverses is rolling in substantial
section of the project which is intercepted by mountainous terrain in some sections.

Potential of the area:

In the project area limited crop production, livestock and livestock products are available in the
area of influence of the road project even though the area is under attention to reverse food
deficit. There is an initiative to change the area that the potential resources of oil mining and salt
production may attract private investors and governmental agencies.

1.4 Scope of the project

The scope of the project goes as far as designing the geometry and pavement of a given road
section, with its appropriate drainage structures.

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Section-2: Geometric design

2.1 Geometric design Control and Criteria

2.1.1 Terrain classification

2.1.1.1 Contour generation

The surveying data x, Y and Z coordinate taken from the road corridor using Hand Held GPS are
converted to a contour using GIS software.

2.1.1.2 Selection of center line

The center line of the road is delineated on the given road corridor using the contour elevations
by considering to have minimum earth work along the corridor.

2.1.1.3 Transverse terrain property
In order to know the type of the terrain along the selected center line or corridor, we took
horizontal distance perpendicular to the center line and vertical elevation measurements across
the road. Each measurement is taken longitudinally along the rod at 20m interval to get better
terrain classification. The values obtained are summarized in index table 2-1.
Slop= (vertical elevation / horizontal elevation)*100

Therefore, we generalize the following terrains classification along the road corridor:

STATION

From To TERRAIN AVG. SLOPE
CLASSIFICATION (%)

12+ 500 12+ 760 Rolling 23.14

12 + 760 13+ 080 Mountainous 26.63

13 + 080 13+ 520 Rolling 18.75

13 + 520 13+ 820 Mountainous 32.234

13 + 820 15 +500 Rolling 16.87

Table 2-2 Terrain Classification

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Fig 2-1 Generated contour.

2.1.2 Design traffic volume

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2.1.2.1 Traffic data analysis

In order to design the road, traffic data analysis is very important. Therefore, the secondary data
of traffic analysis we get from the project site comprises traffic volume before design, during
implementation and up to the design life time of the road. As the secondary data shows the
project life is 15 year. The traffic volume data and the design life time are expressed in the
following table.
T&
Year Car 4 WD S/ Bus L/ Bus S/ Truck M/ Truck L/ Truck TOTAL
T

2008 0 4 6 2 12 4 2 14 44

2009 0 5 7 2 13 5 3 16 51

2010 0 5 7 2 14 5 3 16 52

2011 0 6 8 3 14 5 3 17 56

2012 0 6 8 3 15 5 3 18 58

2013 0 15 16 6 31 20 28 34 149

2014 0 16 17 7 34 21 30 37 160

2015 0 19 19 8 36 22 32 39 174

2016 0 19 21 8 38 25 35 41 184

2017 0 19 21 9 40 26 36 44 193

2018 0 20 22 9 43 28 38 46 205

2019 0 21 25 11 44 31 42 49 221

2020 0 22 26 11 47 32 44 52 232

2021 0 22 26 12 49 34 46 53 241

2022 0 22 29 12 52 35 48 56 253

2023 0 25 30 13 55 36 51 59 267

2024 0 25 32 13 57 39 54 60 279

2025 0 26 33 14 60 40 57 64 292

2026 0 27 34 14 62 43 60 67 307

2027 0 28 37 16 66 44 63 70 323

Table 2-3 Traffic data analysis

From the above data,

o Traffic volume when the road open =149 veh/day
o Traffic volume at the end of the project life =323 veh/day
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2.1.3 Road functional classification

Some of the factors which affect road design control and criteria are functional classification of
the road. In Ethiopian case, we have five functional classes based on AADT and importance of
the road.

Since, AADT of the project lies between 200-1000, and the road expected to serve centers of
provisional importance, the road could be main access road (class II).

2.2 Geometric Design Standard

Based on the traffic data obtained from the above table we decide the project design standard to
be (DS4).

Because:-

a) Even if the AADT at the opening of the road (2013) is 149 veh/day it will be greater than
200 veh/ day after five year and it is 323 veh/day at the end of design life (15 years). So it
fulfills the requirements of DS4. Since the recommended traffic volume for DS4 is 200-
1000 veh/day.(ERA)
b) The second reason is that since the area is an oil mining area, we expect the road will
accommodate the expected traffic volume during the design life time.
c) Based on the above reason, we decide the road to be DS4, to get full knowledge from the
whole project since the project is for academic purpose.
Therefore, we took the entire design element based on DS4. Refer the above information from
ERA manual Table 2.1.

From Design Standards vs. Road Classification and AADT table of ERA for DS4,

AADT=200 – 1000 vehicle/day

Surface type = paved

Carriageway = 6.7m

Shoulder width =1.5m for rolling

= 0.5m for mountainous
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Design speed = 70km/hr for rolling

= 60km/hr =for mountainous

2.2.1 Horizontal Alignment
Based on our proposal of the center line of the road, we have tangents and curves. The curves are
curve1, curve2, curve3, curve4, curve5, and curve6.

Based on our terrain classification, the curves fall in to different terrain classification that leads
us to determine the radius and different elements of each curve.

Curve Terrain type

Curve 1 Rolling

Curve 2 Rolling

Curve 3 Rolling

Curve 4 Error! Not a
valid link.

Curve 5 Rolling

Curve 6 Rolling

Table 2-4 Horizontal curves and their terrain classification

Since our road is DS4, the minimum radius of each curve based on the terrain is:-

Minimum horizontal radius = 175m for rolling

= 125m for mountainous

Refer the following table for the rest of the design elements of DS4 (ERA standards)

Design Element Unit Flat Rolling Mountainous Escarpment Urban/Peri- Urban

Design Speed km/h 85 70 60 50 50

Min. Stopping Sight Distance m 155 110 85 55 55

Min. Passing Sight Distance m 340 275 225 175 175

% Passing Opportunity % 25 25 15 0 20

Min. Horizontal Curve Radius m 270 175 125 85 85

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Transition Curves Required Yes Yes No No No

Max. Gradient (desirable) % 4 5 7 7 7

Max. Gradient (absolute) % 6 7 9 9 9

Minimum Gradient % 0.5 0.5 0.5 0.5 0.5

Maximum Super elevation % 8 8 8 8 4

Crest Vertical Curve k 60 31 18 10 10

Sag Vertical Curve k 36 25 18 12 12

Normal Cross fall % 2.5 2.5 2.5 2.5 2.5

Shoulder Cross fall % 4 4 4 4 4

Right of Way m 50 50 50 50 50

Table 2-5: Table 2-6 of ERA Geometric Design Parameters for Design Standard DS4 (Paved)

2.2.1.1 Horizontal curve elements

Curve-1 Design computation

a) Terrain type = Rolling

b) Deflection angle Δ = 390 (by measurement)

c) Point of intersection P.I=12+717.4m

d) Calculation of radius of the curve

Vd 2
Rmin =
127(e + f )

Where, Rmin=minimum radius

Vd=70km/hr…………….ERA, table 2.6

ed= 8% (max design super elevation rate, ERA, table 2.6)

f=0.14 (ERA. Table 8.1 for ed=8%)

70 2
Then, Rmin = =175.3m
127(0.08 + 0.14)

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The calculated Rmin has no significant change from the recommended in ERA manual standard
(i.e., 175m), in addition to this, in order to minimize cut and fill, we use R min=175m from the
standard.

Therefore, radius of curve=Rc=175m

e) Tangent (T1)

 ∆
T1 = R * tan 
2

 39 
T1 = 175 * tan   = 61.97 m
 2 

f) Point of curvature (PC)

P.C1= P.I1 - T1

=12+717.4 – 0+061.97

=12+655.43m

g) Length of the curve (L)

 2Π 
L1 = ∆ * R *  
 360 

 2Π 
L1 = 390 *175 *   = 119.12m
 360 

h) Point of tangency (P.T)

P.T1= P.C1+L1

=12+655.43+119.12

=12+774.55m

i) External distance (E)

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 ∆ 
E1 = R * sec  − 1
 2 

  39  
E1 = 175 * sec  −1 = 10.65m
  2  

j) Middle ordinate (M)

  ∆ 
M 1 = R * 1 − cos 
  2 

  39 
M 1 = 175 * 1 − cos  = 10.04m
  2 

k) Chord (Chord from P.C to P.T)

∆
C1 = 2 R sin  
2

 39 
C1 = 2 *175 * sin   = 116.83m
 2 

Fig.2.2 elements 0f curve-1
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b) Deflection angle Δ = 330 (by measurement)



Vd 2
Rmin =
127(e + f )





70 2
127(0.08 + 0.14)

(i.e., 175m), in addition to this to prevent overlaps with curve 3, we use Rmin=175m from the
standard.


e) Tangent (T1)

Rmin = 175m

 ∆
T2 = R * tan  
2

 33 
T2 = 175 * tan   = 51.84m
 2 


13



P.C2= P.I2 – T2

=13+150.43– 0+051.84

=13+098.59m


 2Π 
L2 = ∆ * R *  
 360 

 2Π 
L2 = 330 *175 *   = 100.79m
 360 


P.T2= P.C2+L2

=13+98.59+100.79

=13+199.38m


 ∆ 
E2 = R * sec  − 1
 2 

  33  
E2 = 175 * sec  −1 = 7.52m
  2  


  ∆ 
M 2 = R * 1 − cos 
  2 

  33 
M 2 = 175 * 1 − cos  = 7.21m
  2 


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 ∆
C2 = 2 R sin  
2

 33 
C2 = 2 *175 * sin   = 99.41m
 2 

Fig 2.3 elements of curve-2



b) Deflection angle Δ = 59.620 (by measurement)



Vd 2
Rmin =
127(e + f )




15



70 2
127(0.08 + 0.14)

(i.e., 175m), in addition to this to prevent overlaps with curve 2, we use R min=175m from the
standard.


e) Tangent (T3)

Rmin = 175m

∆
T3 = R * tan  
2

 59.62 
T3 = 175 * tan   = 100.26m
 2 


P.C3= P.I3 - T3

=13+363.64– 0+100.26

=13+263.38m


 2Π 
L3 = ∆ * R *  
 360 

 2Π 
L3 = 59.62 0 *175 *   = 182m
 360 


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P.T3= P.C3+L3

=13+263.38+182m

=13+445.38m


 ∆ 
E3 = R * sec  − 1
 2 

  59.62  
E3 = 175 * sec  −1 = 26.69m
  2  


  ∆ 
M 3 = R * 1 − cos 
  2 

  59.62 
M 3 = 175 * 1 − cos  = 23.17 m
  2 


∆
C3 = 2 R sin  
2

 59.62 
C3 = 2 *175 * sin   = 173.99m
 2 





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Vd 2
Rmin =
127(e + f )





70 2
Then, Rmin = =175.37 m
127(0.08 + 0.14)

(i.e., 175m), so we use Rmin=175m from the standard.

But to make the curve smooth, we took R=236m, I.e. =RC=236m

e) Tangent (T4)

R = 236m

∆
T4 = R * tan 
2

 90.81 
T4 = 236 * tan   = 239m
 2 


P.C4= P.I4 – T4

=14+045.5– 0+239

=13+806.5m


 2Π 
L4 = ∆ * R *  
 360 

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 2Π 
L4 = 90.810 * 236 *   = 374.m
 360 


P.T4= P.C4+L4

=13+806.5+374m

=14+180.5m


 ∆ 
E4 = R * sec  − 1
 2 

  90.81  
E4 = 236 * sec  −1 = 100.12m
  2  


  ∆ 
M 4 = R * 1 − cos 
  2 

  90.810 
M 4 = 236 * 1 − cos
 2  = 70.31m

  


 ∆
C4 = 2 R sin  
2

 90.810 
C 4 = 2 * 236 * sin 
 2  = 336.10 m

 



19






Vd 2
Rmin =
127(e + f )





70 2
127(0.08 + 0.14)

standard.


e) Tangent (T5)

Rmin = 175m

∆
T5 = R * tan 
2

 44.15 
T5 = 175 * tan   = 70.97 m
 2 


P.C5= P.I5 – T5

=14+756.69– 0+70.97m

20



=14+685.72m


 2Π 
L5 = ∆ * R *  
 360 

 2Π 
L5 = 44.150 *175 *   = 134.85m
 360 


P.T5= P.C5+L5

=14+685.72+134.85m

=14+820.57m


 ∆ 
E5 = R * sec  − 1
 2 

  44.150  
E5 = 175 * sec
  −1 = 13.84m

  2  


  ∆ 
M 5 = R * 1 − cos 
  2 

  44.15 
M 5 = 175 * 1 − cos  = 12.83m
  2 


∆
C5 = 2 R sin  
2

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 44.150 
C5 = 2 *175 * sin 
 2  = 131.54m

 






Vd 2
Rmin =
127(e + f )





70 2
127(0.08 + 0.14)

standard.


e) Tangent (T6)

Rmin = 175m

 ∆
T6 = R * tan  
2

22



 32.48 
T6 = 175 * tan   = 50.97 m
 2 


P.C6= P.I6 – T6

=15+226.73m – 0+050.97

=15+175.76m


 2Π 
L6 = ∆ * R *  
 360 

 2Π 
L6 = 32.48 0 *175 *   = 99.20m
 360 


P.T6= P.C6+L6

=15+175.76m +99.20m

=15+274.96m


 ∆ 
E6 = R * sec  − 1
 2 

  32.480  
E6 = 175 * sec
  −1 = 7.27 m

  2  


  ∆ 
M 6 = R * 1 − cos 
  2 

23



  32.480 
M 6 = 175 * 1 − cos
 2  = 6.98m

  


∆
C6 = 2 R sin  
2

 32.48 0 
C6 = 2 *175 * sin 
 2  = 97.88m

 

2.2.1.2 Transition curve

When a vehicle traveling on a straight course enters a curve of finite radius, and suddenly
subjected to the centrifugal force which shock and sway. In order to avoid this it is customary to
provide a transition curve at the beginning of the circular curve having a radius equal to infinity
at the end of the straight and gradually reducing the radius to the radius of the circular curve
where the curve begins.

Mostly transition curves are introduced between:-

A/ between tangents and curves

B/ between two curves

Various forms of transition curves are suitable for high way transition, but the one most popular
and recommended for use is spiral.

Design of transition curve

Even if there are places to design transition curve, ERA design manual standard recommends
where and how to design this horizontal alignment design elements. Especially for Ethiopian
road, transition curves are a requirement for trunk and link road segments having a speed equal
to or greater than 80km/hr. (ERA)

But the characteristics of our project road segment is;-

Speed=60km/hr (for mountainous terrain)

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Speed=70km/hr (for rolling terrain)

Terrain= mostly rolling and mountainous

Functional classification=Main access road.

Therefore, based on the ERA standard all curves in the project will not have transition curve. So,
it will be a simple curve with out transition curve.

2.2.1.3 Super elevation

Curve-1

When a vehicles moves in a circular path, it is forced radially by centrifugal force. The
centrifugal force is counter balanced by super elevation of the road way and/or the side friction
developed between the tire and the road surface. The centrifugal force is the result of design
speed, weight of car, friction, and gravitational acceleration having the following relation ship.

Wv 2
Fc =
gR

Where, Fc= centrifugal force

W=weight of the car

V=design speed

g= acceleration due to gravity

R= radius of the curve

So, super elevation rate is changing the road cross section from the normal road to elevate
towards the center of the curve. I.e., it counteracts a part of the centrifugal force, the remaining
part being resisted by the lateral friction.

Terms in super elevation:

 Tangent run out(Lt)
 Super elevation runoff(Lr)

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Tangent run out (Lt)

It is the longitudinal length along the road designed to remove the adverse crown to a zero slope.
i.e., the outer edge of the road is raised from a normal cross slope to a zero slope which equal to
the grade level of the road (the level of the center line of the road).

Super elevation runoff length (Lr)

Super elevation run-off is a length of the road section from the point of removal of adverse
crown of the road to the full super elevated point on the curve.

Super elevation is equal to the length of transition curve when there is a transition curve. When
there is no transition curve i.e., when it is a simple curve,1/3 rd of the length is placed on the curve
and 2/3rd of the length is placed on the tangent part(ERA). Therefore, we follow the second
standard to design our super elevation since all the curves do not have transition curve.

Design computation

A/ computation of super elevation run-off

Super elevation runoff length can be obtained from table 8.5 (ERA) using radius (Rc) and super
elevation rate (e), or it can be computed from the following formula. (AASHTO)

Lr =
( wn1 ) ed ( b )
w
G

Where,

Lr=minimum super elevation run-off (m)

G=maximum relative gradient (percent)

n1=number of lanes rotated

Bw=adjustment factor for number of lane rotated

w=width of one traffic lane (in our case, w/2)

ed=design super elevation rate, percent

26



Then, n1=1, since the number of lane rotated is =1(AASHTO, exhibit 3-31)

bw=1, for one lane rotated(AASHTO, exhibit 3-31)

G=0.55%, for Vd=70km/hr (AASHTO, exhibit 3-31)

Design speed(Km/h)(Vd) Maximum relative Equivalent maximum relative
gradient(%)(G) slope (%)

20 0.80 1:125

30 0.75 1:133

40 0.70 1:143

50 0.65 1:150

60 0.60 1:167

70 0.55 1:182

80 0.50 1:200

90 0.45 1:213

100 0.40 1:227

110 0.35 1:244

120 0.30 1:263

130 0.25 1:286

Table2-6 (Exhibit 3-27 Maximum relative gradients of AASHTO)

 6 .7 
 *1 * 0.08
Therefore,  2 
Lr = (1) = 48.87m
0.55

But ERA recommends Lr=52m for ed=8% and Rc=175m. Thus, take Lr=52m

B/ computation of tangent run out (Lt)

Tangent run-out can be computed using the following equation. (AASHTO)

eNC
Lt = * ( Lr )
ed

Where,
27



Lt =minimum length of tangent run-out

eNC=normal cross slope rate, percent

ed =design super elevation, percent

Lr=super elevation runoff length

0.025
Then, Lt = * ( 52 ) = 16.25m
0.08

C/ Location of super elevation run-off (Lr)

Since there is no transition curve (spiral) between the tangent and the curve in the project, 2/3 rd
of the super elevation length is placed on the tangent and 1/3rd of the length is placed on the
curve part.

1
i.e., * 52 =17.33m (on the curve)
3

2
* 52 = 34.67 m (On the tangent)
3

Then,

The beginning of the super elevation runoff length is:-

=P.C-34.67m

=12+655.43-0+034.67

=12+620.76m

The end of the super elevation runoff length is:-

=P.C+17.33m

=12+655.43+0+017.33m

=12+672.76m

28



D/ location of tangent run-out length

Beginning=beginning of Lr minus Lt

=12+620.76-16.25m

=12+604.51m

End=12+620.76m

E/ station where outer and inner edge of the road will have the same normal cross fall i.e., 2.5%

It is a length(R) where total crown removal is attained.

So, R=2*Lt

=2*16.25

=32.50m,

Then, the station is,

Beginning= station of beginning of adverse crown removal

=12+604.51m

End=station of beginning of adverse crown removal plus +R

=12+604.51+32.50m

=12+637.01m

On the same process we can do the super elevation at the exit of the curve.

We know that the length of curve 1=119.12m

Then the part of the curve to be full super elevated is

=119.12-2*(1/3*Lr)

=119.12-2*(1/3*52)

=84.46m
29



F/ Then, the station of end of full super elevation is

=12+672.76+84.46m

=12+757.22m

G/ station of end of super elevation runoff is

=12+757.22+52m

=12+809.22m

H/ station of recovering adverse crown is

=12+809.22+16.25m

=12+825.47

Attainment of full super elevation:-

From three methods attaining full super elevation we use the method in which rotating the
surface of the road about the center line of the carriageway, gradually lowering the inner edge
and raising the upper edge, keeping the center line constant.

Illustration:

30



Fig.2-4 Attainment of super elevation

Based on the above super elevation attainment, the results are shown on the following figure.

31



Fig.2-5 Super elevation at entrance and exit for curve 1



Lr =
( wn1 ) ed ( b )
w
G

n1=1, since the number of lane rotated is =1(AASHTO, exhibit 3-31)


G=0.55%, (AASHTO, exhibit 3-31)

 6.7 
 *1 * 0.08
Lr = * (1) = 48.78m
0.55



32




eNC
Lt = * ( Lr )
ed

0.025
Then, Lt = * ( 52 ) = 16.25m
0.08


curve part.

1
i.e., * 52 =17.33m (on the curve)
3

2
3

Then,


=P.C-34.67m

=13+98.59-0+034.67

=13+63.92m


=P.C+17.33m

=13+98.59+0+017.33m

=13+115.92m


33




=13+63.92 -16.25m

=13+47.67m

End=13+63.92m



So, R=2*Lt

=2*16.25

=32.50m,

Then, the station is


=13+047.67m


=13+47.67m +32.50m

=13+080.17m


We know that the length of curve-2=100.79m


=100.79-2*(1/3*Lr)

=100.79-2*(1/3*52)

=66.12m

34



=end of Lr+L

=13+115.92 +66.12m

=13+182.04m

G/ station of end of super elevation runoff is

=13+182.04 +52m

=13+234.04m

H/ station of recovering adverse crown are:

=13+234.04+16.25m

=13+250.29m




Lr =
( wn1 ) ed ( b )
w
G



G=0.55%, (AASHTO, exhibit 3-31)

 6.7 
 *1 * 0.08
Lr = * (1) = 48.78m
0.55



35




eNC
Lt = * ( Lr )
ed

0.025
Lt = * ( 52 ) = 16.25m
0.08


curve part.

1
i.e., * 52 =17.33m (on the curve)
3

2
3

Then,


=P.C-34.67m

=13+263.38 -0+034.67 m

=13+228.71m


=P.C+17.33m

=13+263.38 +0+017.33m

=13+280.71m



36



=13+228.71-16.25m

=13+212.46m

End=13+228.71m



So, R=2*Lt

=2*16.25

=32.50m,



=13+212.46m


=13+212.46+32.50m

=13+244.96m


We know that the length of curve 3=182m


=182-2*(1/3*Lr)

=182-2*(1/3*52)

=147.33m


=13+280.71m +147.33m
37



=13+428.04m

G/ station of end of super elevation runoff is:

=13+428.04 +52m

=13+480.04m

H/ station of recovering adverse crown is:

=13+480.04+16.25m

=13+496.29m




Lr =
( wn1 ) ed ( b )
w
G



G=.55%, for Vd=70km/hr, (AASHTO, exhibit 3-31)

 6.7 
 *1 * 0.08
Lr = * (1) = 48.7m
0.55

But from ERA for ed=8% and v=70m/sec, by interpolation Lr=49.12m for Rc=236m. Thus, take
Lr=49.12m



38



eNC
Lt = * ( Lr )
ed

0.025
Lt = * ( 49.12 ) = 15.35m
0.08


curve part.

1
i.e., * 49.12 =16.37 m (on the curve)
3

2
* 49.12 = 32.75m (On the tangent)
3

Then,


=P.C-32.75m

=13+806.5-0+032.75

=13+773.75m


=P.C+16.37

=13+806.5+0+016.37m

=13+822.87m



39



=13+773.75 -15.35m

=13+758.4m

End=13+839.25m



So, R=2*Lt

=2*15.35

=30.7m



=13+823.39m


=13+823.39m +30.70m

=13+854.10m




=374-2*(1/3*Lr)

=374-2*(1/3*49.12)

=341.25m

40



=13+822.87+341.25m m

=14+164.12m


=14+164.12m +49.12m

=14+213.24m


=14+213.24 +15.35m

=14+228.59m




Lr =
( wn1 ) ed ( b )
w
G




 6.7 
 *1 * 0.08
Lr = * (1) = 48.78m
0.55




41



eNC
Lt = * ( Lr )
ed

0.025
Lt = * ( 52 ) = 16.25m
0.08


curve part.

1
i.e., * 52 =17.33m (on the curve)
3

2
3

Then,


=P.C-34.67m

=14+685.72m -0+034.67m

=14+651.05m


=P.C+17.33m

=14+685.72+0+017.33m

=14+703.05m



42



=14+651.05-16.25m

=14+634.80m

End=14+651.05m

E/ Station where outer and inner edge of the road will have the same normal cross fall i.e., 2.5%


So, R=2*Lt

=2*16.25

=32.50m,

Then, the station is;

Beginning=station of beginning of adverse crown removal

=14+634.80m


=14+634.80m +32.50m

=14+667.30m




=134.35-2*(1/3*Lr)

=134.35-2*(1/3*52)

=99.68m


=14+703.05m +99.68m
43



=14+802.73m

G/ station of end of super elevation runoff are:

=14+802.73m +52m

=14+854.73m


=14+854.73m +16.25m

=14+870.98m


A/ computation of super elevation run-off:


Lr =
( wn1 ) ed ( b )
w
G




 6.7 
 *1 * 0.08
Lr = * (1) = 48.78m
0.55


44





eNC
Lt = * ( Lr )
ed

0.025
Lt = * ( 52 ) = 16.25m
0.08


curve part.

1
i.e., * 52 =17.33m (on the curve)
3

2
3

Then,


=P.C-34.67m

=15+175.76m -0+034.67m

=15+141.10m


=P.C+17.33m

=15+175.76m +0+017.33m

=15+193.10m

45





=15+141.10m -16.25m

=15+123.85m

End=15+123.85m



So, R=2*Lt

=2*16.25

=32.50m,



=15+123.85m

End=station of beginning of adverse crown removal plus + R

=15+123.85m +32.50m

=15+156.35m




=99.20-2*(1/3*Lr)

=99.20-2*(1/3*52)

=64.53m
46




=15+193.10+64.53m

=15+257.63m


=15+257.63m +52m

=15+309.63m


=15+309.63m +16.25m

=15+325.88m

Super elevation overlaps:

The end of tangent run out (super elevation runoff length) for curve 2 and the beginning of
tangent run out (super elevation runoff length) of curve 3 overlaps with an amount of:

Over lap= (13+250.29)-(13+212.46)

=42.83m

Therefore, this overlap length has to distribute on the curve part of each curve according to the
following.

Half of the overlap distance has to be added to the part of the curve. I.e. if the overlap length is d,
the part of super elevation on the curve will be

=1/3rd (Lr) +d/2

=17.33+42.83/2m

=38.475m

But this length has to be 40% of length of the corresponding curve.

47



Check:

Lc of curve 2=100.79m

Then, 40%*100.79=40.32>38.745m…………….OK!

Lc of curve 3=182m,

Then, 0.4*182=72.8>38.475m………………………OK!

Re-adjustment for super elevation stations.

Curve-2

1. The beginning of the super elevation runoff length is:-

=P.C-(34.67-21.415) m

=13+98.59-(0+013.25)

=13+085.34m

2. The end of the super elevation runoff length is:-

=P.C+17.33m

=13+98.59+ (0+017.33+21.415) m

=13+137.34m

3. Location of tangent run-out length


=13+085.34m -16.25m

=13+069.09m

End=13+085.34m

4. Station where outer and inner edge of the road will have the same normal cross fall i.e., 2.5%

48



So, R=2*Lt

=2*16.25

=32.50m,



=13+069.09m


=13+069.09m +32.50m

=13+101.59m


We know that the length of curve-2=100.79m


=100.79-2*(1/3*Lr+21.415)

=100.79-2*(1/3*52+21.415)

=23.29m

5. Then, the station of end of full super elevation is

=end of Lr+23.29

=13+137.34m +23.29m

=13+160.63m

6. Station of end of super elevation runoff is

=13+160.63+52m

=13+212.63m
49



7. Station of recovering adverse crown is:

=13+212.63m +16.25m

=13+228.88m

Curve-3

1. The beginning of the super elevation runoff length is:-

=P.C-(34.67-21.415) m

=13+263.38 – (0+013.25) m

=13+250.13m

2. The end of the super elevation runoff length is:-

=P.C+ (17.33+21.415) m

=13+263.38 + (0+38.75) m

=13+302.13m

3. Location of tangent run-out length


=13+250.13m -16.25m

=13+233.88m

End=13+250.13m

4. Station where outer and inner edge of the road will have the same normal cross fall i.e., 2.5%


So, R=2*Lt

=2*16.25

=32.50m,
50





=13+250.13m


=13+250.13m +32.50m

=13+282.63m




=182-2*(1/3*Lr+d/2)

=182-2*((1/3*52) +42.83/2)

=104.50m

5. Then, the station of end of full super elevation is

=13+302.13m +104.50

=13+406.63m

6. Station of end of super elevation runoff is:

=13+406.63m + 52m

=13+458.63m

7/ station of recovering adverse crown is:

=13+458.63m +16.25m

=13+474.88m

51



Fig 2-6 profile, section and station of super elevation, tangent run out for all curves

52



STATIONS

CURVE NUMBER
A B C D E F G H

Curve 1 12+604.51 12+620.76 12+637.01 12+672.76 12+757.22 12+792.97 12+809.22 12+825.47

Curve 2 13+069.09 13+085.34 13+101.59 13+137.34 13+160.63 13+196.38 13+212.63 13+228.88

Curve 3 13+233.88 13+250.13 13+282.63 13+302.13 13+406.63 13+442.38 13+458.63 13+474.88

Curve 4 13+756.4 13+773.75 13+789.10 13+822.87 14+164.12 14+197.89 14+213.24 14+228.59

Curve 5 14+634.80 14+651.05 14+667.30 14+703.05 14+802.73 14+838.48 14+854.73 14+870.98

Curve 6 15+123.85 15+141.10 15+156.35 15+193.10 15+257.63 15+293.38 15+309.63 15+325.88

Table 2-7 stations of super elevation, tangent run out for all curves.

53



2.2.1.4 Curve widening

Widening on a curve is giving extra width on a road curves. This is because:-

 It has been found that the drivers on curves have difficulty in steering their
vehicles to outer edge of road as they are able to on the straight because the rear
wheels do not follow precisely the same path as the front wheels when the
vehicles negotiates a horizontal curve or makes a turn.
 Also there is psychological tendency to drive at greater clearance, when passing
vehicle on curved than on straights. Hence, there is dire necessity for widening
the carriage way on curves.
 On curves the vehicles occupy a greater width because the rear wheels track
inside the front wheels.
Analysis of extra widening on horizontal curves

When vehicles negotiate a curve, the rear wheel generally do not follow the same track as
that of the front wheels. It has been observed that except at very high speed, the rear axle
of a motor vehicles remains in line with the radius of the curve. Since the body of the
vehicle is rigid, therefore, the front wheel will twist themselves at one angle to their axle,
such that vertical plane passing through each wheel is perpendicular to the radius of the
curve in order to trace the path on the curve. This is known as ‘off tracking’.

To determine width (W) it is necessary to select an appropriate design vehicle. The
design vehicle should usually be a truck because the off tracking is much greater for
trucks than for passenger car. (AASHTO) There fore, widening on horizontal curves
depend on:

 The length and width of the vehicle
 Radius of curvature

54



Fig 2-7 widening of pavements on horizontal curves

Let;

L= length of wheel base of vehicle in m.

b=width of the road in m,

w=extra width in m,

R1=radius of the outer rear wheel in m,

R2= radius of the outer front wheel in m,

n=number of lanes

Rc= radius of curvature

The formula obtained from the above geometries for extra widening for more than one
lane (mechanical widening) is:-

n * L2
mechanical..widening = wm =
2 * Rc

The extra widening needed for psychological reasons mentioned above is assumed as:-

55



v
psycho log icalwidening = w p =
10 Rc

There fore, total widening w will be:-

n * L2 v
w= +
2 * Rc 10 Rc

Widening attainment on curves

The following rules apply for attaining widening on both ends of the curve. (AASHTO)

A. widening should be done gradually and has to be realized on the inside edge of un-
spiraled curve (on simple curve) pavements.

B. In the case of a circular curve with transition curves, widening may be applied on the
inside edge or divide equally on either side of the center line.

C. On highway curves without transition curves widening should preferably be attained
along the length of super elevation runoff. A smooth fitting alignment would result from
attaining widening on-one half to two-third along the tangent and the remaining along the
curve.

D. Widening is not necessary for large radius greater than 250m.

Curve-1, 2, 3, 5, and 6 Design computations

Design data: Rc = 175m, n=2

L= take 6m (for the design vehicle usually a truck, corresponding to AASHTO, Single
unit (SU))

V=70m/sec

n * L2 v
w= +
2 * Rc 10 Rc

2 * 62 70
w= + = 0.73m
2 *175 10 175
56



For all curves having a radius between 120 to 250m ERA recommends a minimum of
widening width equal to 0.6m. But we recommend the calculated value 0.73m. So, all the
curves will have the corresponding value unless they are no less than the recommended
value by ERA. Therefore, this widening will be introduced at the inner edge of the
curves. Because all the curves are un spiraled curves.

Fig2-8.widening of pavement on curves

WIDENING STARTING STARTING LAST PT OF END POINT REMARK
WIDTH(M) POINT OF POINT OF FULL OF
WIDENING FULL WIDENING WIDENING
WIDENING

0.73 12+620.76 12+672.76 12+757.22 12+809.22 12+620.76

Table 2-8 widening stations for curve 1


Design data: Rc=236m, N=2, L= take 6m, V=70m/se

57



n * L2 v
w= +
2 * Rc 10 Rc

2 * 62 70
w= + = 0.61m
2 * 236 10 236

CUR WIDENI STARTING STARTING LAST PT OF END POINT
VE NG POINT OF POINT OF FULL OF
NO. WIDTH( WIDENING FULL WIDENING WIDENING
M) WIDENING
C1 0.73 12+620.76 12+672.76 12+757.22 12+809.22

C2 0.73 13+085.34 13+137.34 13+160.63 13+212.63

C2 0.73 13+250.13 13+302.13 13+406.63 13+458.63

C3 0.73 13+839.25 13+822.87 14+164.12 14+213.24

C4 0.61 14+651.05 14+703.05 14+802.73 14+854.73

C5 0.73 15+141.10 15+193.10 15+257.63 15+309.63

C6 0.73 12+620.76 12+672.76 12+757.22 12+809.22

Table2-9 Widening length and stations for all curves.

2.2.1.4 Site distance

Another element of horizontal alignment is the site distance across the inside of the
curves. Sight distance is the distance visible to the driver of a passenger car or the
roadway ahead that is visible to the driver. For highway safety, the designer must provide
sight distances of sufficient length that drivers can control the operation of their vehicles.
They must be able to avoid striking an unexpected object on the traveled way.

Where there are site obstruction( such as walls, cut slops, buildings and longitudinal
barriers) on the inside of curves or the in side of the median lane on divided highways, a
design may need adjustment in the normal high way cross section or change in the
alignment if removal of the obstruction is impractical to provide adequate site distance.
Because of the many variables in alignment, in cross section and in the number, type and
58



location of potential obstructions, specific study is usually need for each individual curve.
With site distance for the design speed as a control, the designer should check the actual
conditions on each curve and make the appropriate adjustment to provide adequate
distance.

Two-lane rural highways should generally provide such passing sight distance at frequent
intervals and for substantial portions of their length.

Stopping site distance

Stopping sight distance is the distance required by a driver of a vehicle traveling at a
given speed to bring his vehicle to a stop after an object on the road way becomes visible.
The minimum stopping sight distance is determined from the following formula, which
takes into account both the driver reaction time and the distance required to stop the
vehicle. The formula is:

d= (0.278) (t) (v) +v2/ 254f

Where:

d = distance (meter)

t = driver reaction time, generally taken to be 2.5 seconds

V = initial speed (km/h)

F = coefficient of friction between tires and roadway (see Table 7-1)

OR the stopping site distance is given in ERA manual in the following table.

Design Speed Coefficient Stopping Sight Passing Sight Reduced Passing
Sight Distance
(km/h) of Friction (f) Distance (m) Distance (m) for design (m)
from formulae

20 0.42 20 160 50

30 0.40 30 217 75
59



40 0.38 45 285 125

50 0.35 55 345 175

60 0.33 85 407 225

70 0.31 110 482 275

85 0.30 155 573 340

100 0.29 205 670 375

120 0.28 285 792 425

Table 2-10: Sight Distances

The coefficient of friction values shown in Table 2-10 have been determined from test
using the lowest results of the friction tests. The values shown in the third column of the
above table for minimum stopping sight distance are rounded from the above formula.
For the general use in the design of horizontal curve, the sight line is a chord of the curve,
and the stopping site distance is measured along the center line of the inside lane around
the curve.

The horizontal site line offset needed for clear site areas that satisfy stopping site distance
can be derived from the geometry for the several dimension explained in the following
figure.

60



Fig 2-9 Site distance for horizontal curves

Relevant formulae are as follows:

∆
Siteline( S ) = 2 R sin
2

 ∆
Middle..ordinate(d ) = R1 − cos 
 2

Where ∆ = Deflection angle

R=radius (from the center line of the inner lane)

Design computation

Using the above formulas the stopping site distance(d), the line of site(S) and middle
ordinate(M) of each horizontal curves can be calculated from the data’s of each curve
organized in the following table below.

driver
deflection Radius speed(V) reaction Coefficient of
curve no time
angle(D) (R),m km/hr friction(f)
(t) in sec.
Curve 1. 39 173.325 70 2.5 0.31

Curve 2. 33 173.325 70 2.5 0.31

Curve 3. 59.62 173.325 70 2.5 0.31

Curve 4. 90.81 234.325 70 2.5 0.31

Curve 5. 44.15 173.325 70 2.5 0.31

Curve 6. 32.48 173.325 70 2.5 0.31

Table 2-11 different data about each curve

∆
Siteline( S ) = 2 R sin
2

61



 ∆
Middle..ordinate( d ) = R1 − cos 
 2

v2
Stoppingsitedist..(d ) = 0.278vt +
254 f

Curve Site line (S) Middle Stopping site distance(m)
in m. ordinate (M)
in m. Calculated Recommended by
distance in m ERA

curve 1 115.714 9.94 510.55 110

curve 2 98.454 7.14 510.55 110

curve 3 172.329 22.93 510.55 110

curve 4 333.72 69.81 510.55 110

curve 5 130.278 12.76 510.55 110

curve 6 96.945 6.92 510.55 110

Table2-12 Site distance elements

62



Fig 2-10 stopping site distance of curve 1

Passing site distance

Passing sight distance is the minimum sight distance on two-way single roadway roads
that must be available to enable the driver of one vehicle to pass another vehicle safely
without interfering with the speed of an oncoming vehicle traveling at the design speed.
Within the sight area the terrain should be the same level or a level lower than the
roadway. Otherwise, for horizontal curves, it may be necessary to remove obstructions
and widen cuttings on the insides of curves to obtain the required sight distance. The
passing sight distance is generally determined by a formula with four components, as
follows:

d1 = initial maneuver distance, including a time for perception and reaction

d2 = distance during which passing vehicle is in the opposing lane

d3 = clearance distance between vehicles at the end of the maneuver

d4 = distance traversed by the opposing vehicle

The formulae for these components are as indicated below:
63



d1 = 0.278 t1 (v – m + at1/2)

Where,

t1 = time of initial maneuver, s

a = average acceleration, km/h/s

v = average speed of passing vehicle, km/h

m = difference in speed of passed vehicle and passing vehicle, km/h

d2 = 0.278 vt2

Where,

t2 = time passing vehicle occupies left lane, sec.

v = average speed of passing vehicle, km/h

d3 = safe clearance distance between vehicles at the end of the maneuver, is dependent on
ambient speeds as per Table 7-2 of ERA standard:

Table 7-2: Clearance Distance (d3) vs. Ambient Speeds

Speed Group (km/h)

Speed group(km/hr) 50-65 66-80 81-100 101-120

D3(m) 30 55 80 100

d4 = distance traversed by the opposing vehicle, which is approximately equal to 2/3 rd of
d2 whereby the passing vehicle is entering the left lane, estimated at:

d4 = 2d2/3

The minimum Passing Sight Distance (PSD) for design is therefore:

PSD = d1+ d2 + d3 + d4

64



Even if it is calculated using the above formula ERA recommends passing site distance,
so we use the value given by ERA design manual.

Sample calculation

Curve 1

Data:

Design speed=70km/hr=v of passing vehicle

Assume the following values

T1=3.5 sec, T2=3sec, a=1.0m/sec2

V of passing vehicle=70km/hr

V of passed vehicle=65km/hr

i.e., m=70-65=5km/hr

Then,

d1= 0.278 t1 (v – m + at1/2)

d1 = 0.278 *3.5* (70 – 5 + (1*3)/2) =64.71m

d2= 0.278 vt2= 0.278 *70*3 =58.38m

d3=55m, for design speed group=66km/hr-80km/hr

d4= 2d2/3 = (2*58.38)/3 =38.92m

Therefore, total passing site distance is,

PSD=d1+d2+d3+d4 = Error! Not a valid link.Error! Not a valid link.Error! Not a valid
link.Error! Not a valid link. =218.95m

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Fig 2-11 Components of passing maneuver used in passing site distance.

2.2.2 Design of vertical alignment

The two major aspects of vertical alignment are vertical curvature, which is governed by
sight distance criteria, and gradient, which is related to vehicle performance and level of
service. The purpose of vertical alignment design is to determine the elevation of selected
points along the roadway, to ensure proper drainage, safety, and ride comfort. So it is
important to use different series of grades and to create a smooth transition between these
grades parabolic curves are used. The vertical alignment includes:

 Joining the grades with smooth curve.
 Location of appropriate gradients.
2.2.2.1 Design consideration

2.2.2.1.1 Gradient and grade controls

Changes of grade from plus to minus should be placed in cuts, and changes from a minus
grade to a plus grade should be placed in fills.Highway should be designed to encourage
uniform operation throughout the stretch.In the analysis of grades and grade control, one
of the most important considerations is the effect of grades on the operating of the motor

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vehicle.Determination of grades for vertical alignment the following are taken in to
consideration for;

1. The maximum limit of grades.

 Visibility related to sight distance.
 Stopping sight distance.
 Passing sight distance.
 Rider and passenger comfort.
 Cost of vehicle operation
 General appearance
 Cut and fill (earth work)

2. The minimum limit of grades.

 Drainage purpose
In this project the two cases are taken in to account as recommended by ERA 2001.

2.2.2.1.2 Vertical curves

A vertical curve provides a smooth transition between two tangent grades. There are two
types of vertical curves. Crest vertical curves and sag vertical curves.

 When a vertical curve connects a positive grade with a negative grade, it is
referred to as a crest curve.
 When a vertical curve connects a negative grade with a positive grade, it is
termed as a sag curve.
In this project crest and sage curves are applied to create a smooth transition between
these grades.

Length of vertical curves

Crest curves:

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For crest curves, the most important consideration in determining the length of the curve
is the sight distance requirement.

 Sight distance
— stopping and
— passing sight distance
Sag curves:

For sag curves, the criteria for determining the length of the curve are:

 vehicle headlight distance,
 rider comfort,
 drainage control and
 General appearance.
When the computed curve length for the above requirements is less than the minimum
curve length recommended by ERA2001, this recommended value is taken as curve
length.

Error! Not a valid link.Site distance (Both stopping and passing)

For Crest Vertical Curve
The stopping sight distance is the controlling factor in determining the length of a crest
vertical curve.
Minimum Length required for safe stopping calculated (from AASHTO)

When Sd ≥ Lvcmin

When Sd ≤ Lvcmin

The 100 in the above equations are to convert A from % into decimals.
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Where Lvc min = Minimum length of vertical curve compute

Sd = Min. Stopping Sight Distance = 85 m for mountainous terrain.

Psd = Min. Passing Sight Distance = 225 m for mountainous terrain.

Sight distances should be checked during design, and adjustments made to meet the
minimum requirements. The following values should be used for the determination of
sight lines. Shown in the figures below:

Fig 2-12 Site distance for crust curve

ERA Manual recommends that:

h1= Driver's eye height = 1.07 meters

h2 = Object height for stopping sight distance = 0.15 meters

= Object height for passing sight distance: = 1.30 meters

For sag Vertical Curve
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Figure below shows the driver’s sight limitation when approaching a sag vertical curve.
The problem is more obvious during the night time when the sight of the driver is
restricted by the area projected by the headlight beams of vehicle. Hence, the angle of the
beam from the horizontal plane is also important. This design control criteria is known as
headlight sight distance. The headlight height of h = 0.6 m and upward angle for the
headlight projection cone of β =1° is normally assumed. The governing equations are
(from AASHTO)

When Sd ≥ Lvcmin

When Sd ≤ Lvcmin

Fig 2-13 Site distance for sag curve

A driver may experience discomfort when passing a vertical curve. The effect of
discomfort is more obvious on a sag vertical curve than a crest vertical curve with the
same radius, because the gravitational and centripetal forces are in the opposite
directions. Some of the ride discomfort may be compensated by combination of vehicle
weight, suspension system and tire flexibility. The following equation has been

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recommended by AASHTO as the minimum length of a vertical curve that will provide
satisfactory level of ride comfort.

Design standards from ERA manual:

Urban/Peri- Urban
Design Element Unit Flat

Mountainous

Escarpment
Rolling

Design Speed km/h 85 70 60 50 50

Min. Stopping Sight Distance m 155 110 85 55 55

Min. Passing Sight Distance m 340 275 225 175 175

% Passing Opportunity % 25 25 15 0 20

Max. Gradient (desirable) % 4 5 7 7 7

Max. Gradient (absolute) % 6 7 9 9 9

Minimum Gradient % 0.5 0.5 0.5 0.5 0.5

Crest Vertical Curve k 60 31 18 10 10

Sag Vertical Curve k 36 25 18 12 12

Table 2-13 Design Parameters for Design Standard DS4 (Paved)

Phasing: Even if we face phasing problem on vertical curve 1 with horizontal curve 3
and vertical curve 3 with horizontal curve 5, we took a corrective action by separating
them again vertical curve 2 and horizontal curve 4 corrected by making the ends of the
curves to end at a common station in the design process according to ERA.

2.2.2.2. Computation of gradients
1. Gradient of the first alignment (g1)
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To calculate the first gradient;
Elevation of the first point = 1386 m
Elevation of the second point = 1395.4 m
Elevation difference = 1395.4-1386 = 9.4 m
Horizontal distance b/n the two points = (13+572)-(12+500) = 1072 m
Gradient (Slope) = elevation difference/horizontal distance
= (9.4/1072) = 0.0088
Gradient (Slope) g1 = 0.88 %
2. Gradient of the second alignment (g2)
To calculate the second gradient;

Elevation of the first point = 1395.4 m

Elevation of the second point = 1375 m

Elevation difference = 1375-1395.4 = -20.4 m

Horizontal distance b/n the two points = (14+000)-(13+572) = 428 m

Slope (gradient) = elevation difference/ horizontal distance

= -20.4/430 = -0.0477

Gradient (Slope) g2 = -4.77 %

3. Gradient of the third alignment (g3)

To calculate the third gradient



Elevation difference = 1377-1375 = 2m

Horizontal distance b/n the two points = (14+480)-(14+000) = 480m

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Gradient (Slope) = elevation difference/ horizontal distance

= (2/480) = 0.0042

Gradient (Slope) g3 = 0.42 %

4. Gradient of the forth alignment (g4)

To calculate the forth gradient



Elevation difference = 1352-1377 = -25

Horizontal distance b/n the two points = (15+500)-(14+480) = 1020m

Slope (gradient) = elevation difference/ horizontal distance

= -25/1020 = -0.0245

Gradient (Slope) g4= -2.45%

Elevation station
Horizontal
second Second Slope
Grade First point point Elev. diff. First point point distance(m) (%)

g1 1386 1395.4 9.4 12500 13572 1072 0.88

g2 1395.4 1375 -20.4 13572 14000 428 -4.77

g3 1375 1377 2 14000 14480 480 0.42

g4 1377 1352 -25 14480 15500 1020 -2.45

Table 2-14: Summery of gradients of vertical alignment

2.2.2.5 Computation of vertical curve elements

There are three vertical curves in this project;

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The first vertical curve is a crest curve connects a positive grade with a negative grade;
i.e. 0.88 % and -4.77 %.

The second curve is a sag curve connects a negative grade with a positive grade ;

i.e. -4.77 % and 0.42 %.

The third curve is a crest curve connects a positive grade with a negative grade;

i.e. 0.42 % and -2.45 %.

1. For Curve one (crest curve)
Station of PVI = 13+572

Elevation PVI = 1395.4 m

Gradient, g1 = 0.88 %

Gradient, g2 = -4.77 %

Grade Algebraic difference of grades (A)

A = g2-g1 =0.88 - (-4.77) = /5.64/ = 5.64 %

Computation of the curve length

a) Curve length required for minimum curvature, k

The value of K = 18 for DS4 from design standard, and Mountainous

Lvcmin = AK = 5.64*18 = 101.58 m

But to get smooth vertical curve to different safety purpose we increase LVC from
101.58 to 120 m

b) Length required for safe stopping

When Sd ≥ Lvcmin

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c) Length required for safe passing

When Sd ≥ Lvcmin

d) Length required for ride comfort

e) Length required for aesthetic (appearance)

Lvcmin = 30 *A = 30*5.64 =169m

There fore the maximum of the above values Lvcmin = 301.90 m is to be provided as
curve length, but this curve length over lap with one side of horizontal curve. Therefore
we provide minimum curve length recommended by ERA2001, which is LC = 200m. So
this value is provided as curve length and we post traffic sign that prevent passing for that
specific area.

Curve grade tabulation

From above table 2-14; g1=0.88 %, g2 = -4.77 % and LVC = 200 m,
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Elev.PVI = 1395.4 m

Elev.PVC = Elev.PVI – (g1* LVC/2 )

= 1395.4 – (0.0088*200/2) = 1394.52 m

Finished grade = (Ele.PVC +g1x) + ((g2-g1) x2)/2LV

Tangent Finished
STA.PVC X g1*X% (g2- g1)x2)/2LVC
grade(Ele.PVC+g1x) grade

13472 0 0 1394.62 0 1394.52

13492 20 0.16 1394.77 -0.06 1394.64

13512 40 0.31 1394.93 -0.22 1394.65

13532 60 0.47 1395.09 -0.50 1394.54

13552 80 0.63 1395.24 -0.89 1394.32

13572 100 0.78 1395.40 -1.39 1393.99

13592 120 0.94 1395.56 -2.00 1393.54

13612 140 1.10 1395.71 -2.72 1392.99

13632 160 1.25 1395.87 -3.55 1392.31

13652 180 1.41 1396.03 -4.50 1391.53

13672 200 1.57 1396.18 -5.55 1390.63

Table 2-15 finished grade tabulation for curve-1

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Fig. 2-14 elements of vertical curve-1

2. Curve Two (sag curve)
Elements of sag curve.


Elevation PVI = 1383.63 m


Gradient ( g1) = -4.77 % , Gradient(g2) = 0.42 %

A = g2-g1 = 0.42-(-4.77) = /5.18/ = 5.18 %


The value of K = 25 for DS4 design standard, and Rolling.

L =AK=5.18*25 = 129.50 m

But to get smooth vertical curve for different safety purpose we increase L VC from
129.50 to 150 m


When Sd ≥ Lvcmin

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When Sd ≥ Lvcmin


Lvcmin = 30 *A = 30*5.18 =155 m

curve length. But to get smooth vertical curve for different safety purpose we increase
LVC from 352.92 to 362 m.


From above table 2-14 ; g1= 0.42 , g2 = -4.77 , and LVC = 362 m, Elev.PVI = 1375 m

Elev.PVC = Elev.PVI – (g1* LVC/2)

= 1395.4 – (0.0042*362/2) = 1383.63 m

Finished grade= (Ele.PVC +g1x) + ((g2-g1) x2)/2LVC)
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Tangent grade ((g2-g1)x2)
STA.PVC X g1*X% Finished grade
(Ele.PVC +g1x) 2LVC

13819 0 0 1383.63 0 1383.63

13839 20 -0.95 1382.67 0.03 1382.70

13859 40 -1.91 1381.72 0.11 1381.84

13879 60 -2.86 1380.77 0.26 1381.03

13899 80 -3.81 1379.81 0.46 1380.27

13919 100 -4.77 1378.86 0.72 1379.58

13939 120 -5.72 1377.91 1.03 1378.94

13959 140 -6.67 1376.95 1.40 1378.36

13979 160 -7.63 1376.00 1.83 1377.83

13999 180 -8.58 1375.05 2.32 1377.37

14019 200 -9.53 1374.09 2.86 1376.96

14039 220 -10.49 1373.14 3.46 1376.61

14059 240 -11.44 1372.19 4.12 1376.31

14079 260 -12.39 1371.23 4.84 1376.07

14099 280 -13.35 1370.28 5.61 1375.89

14119 300 -14.30 1369.33 6.44 1375.77

14139 320 -15.25 1368.37 7.33 1375.71

14159 340 -16.21 1367.42 8.28 1375.70

14179 360 -17.16 1366.47 9.28 1375.75

14181 362 -17.25 1366.37 9.38 1375.75


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Curve Three (Crest curve)


Elevation PVI = 1377m

Gradient (g1) = 0.42 %

Gradient (g2) = -2.45 %


A = g2-g1 =0.42 - (-2.45) = /2.87/ = 2.87 %


The value of K = 31 for DS4 design standard, and Rolling

Lvcmin = AK = 2.87*31 = 88.90 m

80



But to get smooth vertical curve to different safety purpose we increase LVC from

88.90 to 120


When Sd ≤ Lvcmi


When Sd ≤ Lvcmi


Lvcmin = 30 *A =30*2.87 = 86 m

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curve length. But to get smooth vertical curve to different safety purpose we increase
LVC from 220.47 to 240m.


From above table: - g1=0.42, g2 = -2.45 and LVC = 240 m, Elev.PVI = 1377 m

Elev.PVC = Elev.PVI – (g1* LVC/2) = 1377– (0.0042*240/2) = 1376.50m

Finished grade= (Ele.PVC +g1x) + ((g2-g1) x2)/2LVC)

Tangent grade
(g2-g1)x2) Finished
STA.PVC X g1*X% (Ele.PVC
2LVC grade
+g1x)

14360 0 0 1376.50 0 1376.50

14380 20 0.083 1376.58 -0.02 1376.56

14400 40 0.167 1376.67 -0.10 1376.57

14420 60 0.250 1376.75 -0.22 1376.53

14440 80 0.333 1376.83 -0.38 1376.45

14460 100 0.417 1376.92 -0.60 1376.32

14480 120 0.500 1377.00 -0.86 1376.14

14500 140 0.583 1377.08 -1.17 1375.91

14520 160 0.667 1377.17 -1.53 1375.64

14540 180 0.750 1377.25 -1.94 1375.31

14560 200 0.833 1377.33 -2.39 1374.94

14580 220 0.917 1377.42 -2.89 1374.53

14600 240 1.000 1377.50 -3.44 1374.06


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Vertical LVC
A K LVCmin LVC adj Sta. PVI Sta.PVC Sta.PVT Elev.PVI Elev.PVC
Curve provide

VC1 5.64 18 101.58 120 200 13+572 13+472 13+672 1395.4 1394.52

VC2 5.18 25 129.50 150 362 14+000 13+819 14+181 1375 1383.63

VC3 2.87 31 88.90 120 240 14+480 14+360 14+600 1377 1376.50

Table 2-18 summery of vertical curves

2.2.3 Road cross sections

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A cross sectional elements in the high way design pertains to those features which deals
with its width. They will normally consist of the carriage way, shoulders, right of way,
roadway width, pavement width, the median, side slopes, drainage features and earth
work profiles.

Carriage way:

The part of the road constructed for use by moving traffic as traffic lanes. For our project
for DS4 and main access road ERA recommends 6.7m.

Lane width

Feature of a high way having great influence on safety and comfort in the width of the
carriage way, due to this we use a lane width of 3.35 m which is recommended for DS4
road are shown in table 2.6 ERA 2001 for all roads design standards.

Shoulders

Shoulder is:-

 Is the portion of the road between the outer edges and the edges of the carriage-
way are called shoulders.
 Is the portion of the roadway contiguous to the carriageway for the
accommodation of stopped vehicles; traditional and intermediate non-motorized
traffic, animals, and pedestrians; emergency use; the recovery of errant vehicles;
and lateral support of the pavement courses. It will provide wherever possible for
emergency stopping and lateral support of the carriageway pavement.
Where the carriageway is paved, the shoulder should also be sealed with a single
bituminous surface treatment. This has several advantages. It would prevent edge
raveling and maintenance problems associated with parking on a gravel shoulder.
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Sealing of the shoulder is recommended under the following conditions:

• Where the total resulting gradient exceeds 25 per cent, it is recommended for
paved shoulder as the width is only 1m; this will reduce the frequent
maintenance needs in mountainous and escarpment terrains.
• Where the shoulder material is readily erodible or where the availability of
material for shoulder maintenance is restricted.
• Wherever there is significant pedestrian traffic in town and village areas.
Based on the above idea, ERA recommends a shoulder width based on design standard
and terrain classification. So, for this project since most of the route has a terrain of
rolling we took 1.5m for shoulder width as recommended by ERA manual. So, we took
1.5m shoulder throughout the route simplicity of the construction.

Road way:

It consists of the carriage way and shoulders and parking lanes. I.e., for this project road
way width will be 6.7+1.5+1.5=9.7m

Right-of-way

It is the width of the land secured and preserved to the public for road purposes. The
right-of-way should be adequate to accommodate all the elements that make-up the cross
section of the high way and may reasonably provide future development.

For this project having design standard of DS4, ERA recommends a right of way width to
be 50m for all terrain type.

Normal cross fall

Normal cross fall should be sufficient to provide adequate surface drainage whilst not
being so great as to make steering difficult, but it should facilitate drainage of the
pavement. It is depend up on the smooth of the surface and the intensity of the rain fall.

Therefore, we took 2.5% for normal cross fall for design standard of DS4 as
recommended by ERA.

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Shoulder cross fall

It should be designed steeper than the pavement to facilitate quick drainage. Therefore we
took 4% for shoulder cross slope as recommended by ERA.

Side slope and back slope

Side slopes and back slopes should be designed to insure the stability of the road way and
to provide a reasonable opportunity for recovery of an out-of-control vehicle.

The selection of a side slope and back slope is depending on safety consideration, height
of cut or fill and economic consideration. ERA 2001 table 6.1 indicates the side slope
recommended for use in the design according to the height of cut and fill and the
material.

Side slope Back
material Height of slope
cut fill slope

Earth or 0.0-1.0m 1:4 1:4 1:3
soil
1.0-2.0m 1:3 1:3 1:2

Over 2m 1:2 1:2 1:1.5

rock Any height See standard details

Table2-19 Side and back slope

Depending to the given standard ratio our project is designed and set out the appropriate
and economical road section.

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Fig 2-17 Elements of road cross section

Section-3: Drainage Standards and Structure Design
3.1 General

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• 






• 




• 
















88



89



90



2.2 Minor drainage analysis and design

2.2.1 Hydrological/ Hydraulic Analysis of Ditch





• 

• 

• 

• 



• 

 

 





- 

- 

- 





91





 runoff 
  
 ra inf all 








a) 

 



- 


- 



overlandtraveldis tan ce
 velocityoflow



2 1
 V = 1 R 3 S 2
n






92



- 


- 




- 

- 




















93














• 




 Ө





 







94





1) 

2) 
3) 












 



 

 












95











 2 1
1
V = R3S 2
n
























96









• 
• 
• 







2.2.2 Structural design of ditch









• 
• 
• 
• 







97





a) 
b) 
























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Catchment upper lower TC
A(ha) Cc L(m) s(%) Tc(s) I Q(m3/s)
Area elev. elev. provide

1 2.18 0.25 1410.5 1385 312.84 0.08 4.27 7.0 180 0.27

2 3.22 0.25 1408.5 1385 306.53 0.08 4.31 7.0 180 0.40

3 7.88 0.25 1406.5 1387 365.89 0.05 5.68 7.0 180 0.99

4 14.00 0.25 1410.5 1387 500.26 0.05 7.58 7.6 149 1.45

5 6.11 0.25 1410 1386 334.31 0.07 4.72 7.0 180 0.76

6 3.70 0.25 1408 1386 400.79 0.05 6.02 7.0 180 0.46

7 9.75 0.25 1400 1366 431.99 0.08 5.55 7.0 180 1.22

8 7.57 0.25 1393.5 1366 367.12 0.07 4.99 7.0 180 0.95

9 32.57 0.25 1391 1346 1082.8 0.04 14.40 14.4 135 3.06

10 0.82 0.25 1352 1346 354.64 0.02 8.62 8.6 165 0.09

Cath. L(m) W(m) A ha Cp Bed L(m) Tc (s) Tcprovide I Qasp(m3/s)
Q,asphalt(m3/s) Q,the Q total n d
Slope% B( bott B(top) Velocit Free D
land(m3/s) om) y board provide
(m)

1 95.35
0.031 6.85 0.0653 0.30 0.95
0.27 0.016 0.025
0.26 93.8 2.6633
0.30 0.61 7
2.53 180 0.3 0.031273
0.56
2 133.18
0.044 6.85 0.40.0912 0.44 0.95
0.016 0.025
0.30 130.9 3.4425
0.35 0.70 7
2.79 180 0.3 0.04368
0.60
3 318.91
0.105 6.85 0.2185 1.09 0.95
0.99 0.016 0.025
0.42 310.62 6.6964
0.49 0.98 7
3.51 180 0.3 0.104595
0.72
4 526.1
0.149 6.85 0.3604 1.60 0.95
1.45 0.016 0.025
0.49 495.06 9.5877
0.57 1.13 9.6
3.85 155 0.3 0.148584
0.79
5 213.72 6.85 0.1464
0.070 0.76 0.83 0.95
0.016 0.025
0.38 206.78 4.8952
0.44 0.89 7
3.27 180
0.3 0.070095
0.68
6 85.79 6.85 0.0588 0.95 0.025 93 2.6458 7 180 0.028137
0.028 0.46 0.49 0.016 0.31 0.36 0.73 2.86 0.3 0.61
7 188.37 6.85 0.129 0.95 0.025 190.74 4.6001 7 180 0.061781
0.062 1.22 1.28 0.016 0.45 0.52 1.04 3.65 0.3 0.75
8 183.74 6.85 0.1259 0.95 0.025 183.94 4.4733 7 180 0.060263
0.060 0.95 1.01 0.016 0.41 0.48 0.96 3.44 0.3 0.71
9 1206.4 6.85 0.8264 0.95 0.025 1136.71 18.184 18.2 110 0.241794
0.242 3.06 3.30 0.016 0.64 0.74 1.49 4.63 0.3 0.94
10 31.8 6.85 0.0218 0.95 0.025 45.68 1.5304 7 180 0.01043
0.010 0.09 0.10 0.016 0.17 0.20 0.40 1.92 0.3 0.47

99









3.3.3 Hydraulics design of
culvert

A culvert is a type of structure that can transmit water as full or partly full. It is a
structure that is designed hydraulically to take advantage of submergence to increase
hydraulic capacity. It is also used to convey surface runoff through embankments. A
culvert can be a structure, as distinguished from bridges, that is usually covered with an
embankment and is composed of structural material around the entire perimeter.

A culvert can be a structure that is 6 meters or less in centerline span length, or between
the extreme ends of openings for multiple boxes.

Full flow is not common for culverts unless governed by a high downstream water
surface elevation. Full flow can be described by fundamental pipe flow. Partly full flow

100



culverts follow the law of open channel flow and need to be classified as either sub
critical or supercritical flow to accomplish the design procedure.

The following are concepts that are important in the hydraulics of culvert design:

Critical depth- the depth at which the specific energy of a given flow rate is at a
minimum. For a given discharge and cross-section geometry, there is only one critical
depth.

Crown- the inside top of the culvert.

Outlet- has tail water equal to or lower than critical depth. For culverts with free outlets, a
lowering of the tail water has no effect on the discharge or the backwater profile
upstream of the tail water.

Improved Inlet- has an entrance geometry that decreases the flow constriction at the inlet
and thus increases the capacity of culverts. These inlets are referred to as either side- or
slope-tapered (walls or bottom tapered).

Invert- is the flow line of the culvert (inside bottom).

Normal flow- occurs in a channel reach when the discharge, velocity, and depth of flow
do not change throughout the reach. The water surface profile and channel bottom slope
will be parallel. This type of flow will exist in a culvert operating on a steep slope if the
culvert is sufficiently long enough.

Slope - Steep water surface slope occurs where the critical depth is greater than the
normal depth. Mild slope occurs where critical depth is less than normal depth.

Submerged- A submerged outlet occurs where the tail water elevation is higher than the
crown of the culvert. A submerged inlet occurs where the headwater is greater than 1.2D.

Design criteria

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Listed below by categories are the design criteria that should be considered for all culvert
designs.

Site criteria

Structure Type Selection

The type of drainage structure specified for a particular location is often determined
based on economic considerations. The following can serve as a guide in the selection of
the type of structure, proceeding from the most expensive to the least expensive. Culverts
are used where bridges are not hydraulically required, where debris is tolerable, and
where they are more economical than a bridge. Culverts can be concrete box culverts,
reinforced concrete pipe culverts, or corrugated metal culverts.

Length and Slope

The culvert length and slope should be chosen to approximate existing topography, and to
the degree practicable:

 the culvert invert shall normally be aligned with the channel bottom and
the skew angle of the stream, and

 the culvert entrance shall match the geometry of the roadway.

Design Features

Culvert Sizes and Shape—the culvert size and shape selected is to be based on
engineering and economic criteria related to site conditions. In evaluating the suitability
of alternate materials, the selection process shall be based on a comparison of the total
cost of alternate materials over the design life of the structure that is dependent upon the
following:

 durability (service life),

102



 cost

 availability

 construction and maintenance ease

 structural strength,

 traffic delays

 abrasion and corrosion resistance, and

 water tightness requirements.

Inlet and Outlet Control

Inlet Control

For inlet control, the control section is at the upstream end of the barrel (the inlet). The
flow passes through critical depth near the inlet and becomes shallow, high velocity
(supercritical) flow in the culvert barrel. Depending on the tail water, a hydraulic jump
may occur downstream of the inlet.

Typical shapes are rectangular, circular, elliptical, and arch.

Nomographs—The inlet control flow versus headwater curves, which are established
using the above procedure, are the basis for constructing the inlet control design
nomographs. Note that in the inlet control nomographs, HW is measured to the total
upstream energy grade line including the approach velocity head.

Outlet Control

Outlet control has depths and velocity that are subcritical. The control of the flow is at the
downstream end of the culvert (the outlet). The tailwater depth is assumed to be critical
depth near the culvert outlet or in the downstream channel, whichever is higher.

103



In a given culvert, the type of flow is dependent on all of the barrel factors. All of the
inlet control factors also influence culverts in outlet control.

Tailwater Elevation—based on the downstream water surface elevation. Backwater
calculations from a downstream control, a normal depth approximation, or field
observations are used to define the tailwater elevation.

Hydraulics—Full flow in the culvert barrel is assumed for the analysis of outlet control
hydraulics. Outlet control flow conditions can be calculated based on an energy balance
from the tailwater pool to the headwater pool.

Design Equations

Equations and Definitions

Losses

HL = HE + Hf+ Hv + Hb + Hj + Hg

Where:

HL = total energy loss, m

HE = entrance loss, m

Hf = friction losses, m

Hv = exit loss (velocity head), m

Hb = bend losses, m

Hj = losses at junctions, m

Hg = losses at grates, m

Velocity

V = Q/A Where:

104



V = average barrel velocity, m/s

Q = flow rate, m3/s

A = cross sectional area of flow with the barrel full, m2

Velocity Head

Hv = V2/2g where g = acceleration due to gravity, 9.8 m/s2

Entrance loss

He = Ke (V2/2g) where Ke = entrance loss coefficient,

Friction Loss

Hf = [(19.63n2L)/R1.33] [V2/2g)

Where:

n = Manning’s roughness coefficient

L = length of the culvert barrel, m

R = hydraulic radius of the full culvert barrel = A/P, m

P = wetted perimeter of the barrel, m

Exit Loss

Ho = 1.0 [(V2/2g) - (Vd2/2g)]

Where: Vd = channel velocity downstream of the culvert, m/s (usually neglected)
& Ho = Hv = V2/2g

Barrel Losses

H = He + Ho+Hf

H = [1 + Ke + (19.63n2L/R1.33)] [V2/2g]

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Energy Grade Line—the energy grade line represents the total energy at any point along
the culvert barrel. Equating the total energy upstream and downstream of the culvert
barrel in the following relationship results:

HWo + ( Vu2/2g) = TW + (Vd2/2g) + HL

Where:

HWo = headwater depth above the outlet invert, m

Vu = approach velocity, m/s

TW = tailwater depth above the outlet invert, m

Vd = downstream velocity, m/s

HL = sum of all losses

Hydraulic Grade Line—the hydraulic grade line is the depth to which water would rise in
vertical tubes connected to the sides of the culvert barrel. In full flow, the energy grade
line and the hydraulic grade line are parallel lines separated by the velocity head except at
the inlet and the outlet.

Nomographs (full flow)—The nomographs were developed assuming that the culvert
barrel is flowing full and:

 TW > D, Flow Type IV Outlet Control or

 dc > D, Flow Type VI Inlet Control

 Vu is small and its velocity head can be considered a part of the available
headwater (HW) used to convey the flow through the culvert.

 Vd is small and its velocity head can be neglected.

HW = TW + H - SoL

Where:

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HW = depth from the inlet invert to the energy grade line, m

H = is the value read from the nomographs, m

SoL = drop from inlet to outlet invert, m

TW should be used if higher than (dc + D)/2.

The following equation should be used:

HW =ho+ H -SoL

Where:

ho = max of(TW ,(dc + D)/2)) m

Adequate results are obtained down to a HW = 0.75D. For lower headwaters,
backwater calculations are required.

Outlet Velocity

Culvert outlet velocities should be calculated to determine the need for erosion protection
at the culvert exit. Culverts usually give outlet velocities that are higher than the natural
stream velocities. These outlet velocities may require flow readjustment or energy
dissipation to prevent downstream erosion. If outlet erosion protection is necessary, the
flow depths and Freud number may also be needed.

In Inlet Control

If water surface profile (drawdown) calculations are necessary, begin at dc at the entrance
and proceed downstream to the exit. Determine at the exit the depth and flow area. Use
normal depth and velocity. This approximation may be used since the water surface
profile converges towards normal depth if the culvert is of adequate length. The outlet
velocity may be slightly higher than the actual velocity at the outlet.

107



In Outlet Control

 The cross sectional area of the flow is defined by the geometry of the outlet and
either critical depth, tailwater depth, or the height of the conduit:

 Critical depth is used when the tailwater level is less than critical depth.

 Tailwater depth is used when tailwater is greater than critical depth, but below the
top of the barrel.

 The total barrel area is used when the tailwater level exceeds the top of the barrel

Roadway Overtopping

Roadway overtopping will begin when the headwater rises to the elevation of the
roadway. The overtopping will usually occur at the low point of a sag vertical curve on
the roadway. The flow will be similar to flow over a broad crested weir.

Qr= Cd L HWr 1.5

Where:

Qr = overtopping flow rate, m3/s.

Cd = overtopping discharge coefficient (weir coefficient) = kf Cr.

kt = submergence coefficient.

Cr = discharge coefficient.

L = length of the roadway crest, m.

HWr = the upstream depth, measured above the roadway crest, m.

108



Total Flow—calculated for a given upstream water surface elevation using equation. In
this equation, roadway overflow plus culvert flow must equal total design flow. A trial
and error process is necessary to determine the flow passing through the culvert and the
amount flowing across the roadway.

Performance Curves

A performance curve is a plot of flow rate versus headwater depth or elevation, velocity,
or outlet scour. The culvert performance curve is made up of the controlling portions of
the individual performance curves for each of the following control sections.

Design Procedure

Step 1 Assemble Site Data and Project File

Hydrographic Survey - Data include

 topographic, site, and location maps

 embankment cross section

 roadway profile

Step 2 Determine Hydrology. Minimum data required—drainage area maps and
discharge-frequency plots

Step 3 Designs Downstream Channel. Minimum data are cross section of channel and the
rating curve for channel

Step 4 Summarize Data on Design Form use data from Steps 1-3

Step 5 Select Design Alternative

Step 6 Select Design Discharge Qd

Step 7 Determine Inlet Control Headwater Depth (HWi)

 for a box shape use Q per foot of width

109



Locate HW/D ratio using a straightedge

 extend a straight line from the culvert size through the flow rate

 mark the first HW/D scale. Extend a horizontal line to the desired scale, read
HW/D, and note on Charts

Calculate headwater depth (HW)

 multiply HW/D by D to obtain HW to energy grade line

 neglecting the approach velocity HWi = HW

 including the approach velocity HWi = HW - approach velocity head

Step 8 Determine Outlet Control Headwater Depth at Inlet (HWoi)

Calculate the tail water depth (TW) using the design flow rate and normal depth (single
section) or using a water surface profile

Calculate critical depth (dc)

 locate flow rate and read dc

 dc cannot exceed D

Calculate (dc + D)/2

Determine (ho)

 ho = the larger of TW or (dc + D/2)

Determine entrance loss coefficient (KE) from ERA design manual Table7-2

Determine losses through the culvert barrel (H):

- use (L) if Manning’s n matches the n value of the culvert and- use (L1) to adjust
for a different culvert n value

110



L1 = L(n1/n)2

Where:

L1 = adjusted culvert length, m

L = actual culvert length, m

n1 = desired Manning n value

n = Manning n value on chart

 mark point on turning line

- use a straightedge and

- connect size with the length

 read (H)

- use a straightedge

- connect Q and turning point and

- Read (H) on Head Loss scale

Calculate outlet control headwater (HW)

 use equation above, if Vu and Vd are neglected

HWoi = H + ho - SoL

if HWoi is less than 1.2D and control is outlet control

- the barrel may flow partly full

- the approximate method of using the greater tailwater or (dc+ D)/2 may not be
applicable

- backwater calculations should be used to check the result and

111



- if the headwater depth falls below 0.75D, the approximate

- method shall not be used

Step 9 Determine Controlling Headwater (HWc)

 compare HWi and HWoi, use the higher

 HWc = HWi, if HWi > HWoi

- the culvert is in inlet control

 HWc = HWoi, if HWoi > HWi

- the culvert is in outlet control.

Step 10 Compute Discharge over the Roadway (Qr)

1. Calculate depth above the roadway (HWr)

HWr = HWc - HWov

HWov = height of road above inlet invert

2. If HWr 0, Qr = 0

If HWr > 0, determine Qr

Step 11 Compute Total Discharge (Qt)

Qt = Qd + Qr

Step 12 Calculate Outlet Velocity (Vo) and Depth (dn)

If inlet control is the controlling headwater

1. Calculate flow depth at culvert exit

use water surface profile

2. Calculate flow area (A)
112



3. Calculate exit velocity (Vo) = Q/A

If outlet control is the controlling headwater

1. Calculate flow depth at culvert exit

 weuse (dc) if dc > TW

 weuse (TW) if dc < TW< D

 weuse (D) if D < TW

2. Calculate flow area (A)

3. Calculate exit velocity (Vo) = Q/A

Step 13 Review Results

Compare alternative design with constraints and assumptions, if any of the

following are exceeded, repeat Steps 5 through 12

Step 14 Plot Performance Curve

Repeat Steps 6 through 12 with a range of discharges

 Qmax if no overtopping is possible

 Qmax = largest flood that can be estimated

Step 15 Related Designs

Culverts out let velocities

The high out let velocities observed at the culvert out let may results in excessive scour of
the channel in the vicinity of the outlet. The variety in the soil type of natural channels
and varying flowing characteristics at the culvert outlet enforces the use different
methods to control or protect the channel against potential damaging effects. Some of the
common used techniques to provide protection against scour are:

113



1. Minor structural element

2. Velocity protection devices

3. Velocity control devices

Minor structural element

Provision of this Minor structural element is done when the culverts exit velocity is 30%
greater than that of the velocity in its natural channel. It minimizes the structural
instabilities. Example Cutoff walls.

Velocity protection devices

For exit velocity greater than 1.3 of velocity in natural channel and less than 2.5 of the
velocity in natural channel.In this case armoring riprap is used. This may be;
Concrete riprap, Vegetation,Synthetic sodding.

Velocity control device

For exit velocity greater than 2.5 of that of natural channels velocity. (In this case energy
dissipater is required.

Nomograph Design

Detail design for channel 4

The following steps show the procedures we followed step by Step to design a culvert for
channel-4 for in the project area especially near the station 15+440.

Step 1 Assemble Site Data and Project File

a. Site survey project file contains:

 roadway profile and

 embankment cross section

 no sediment or debris problems and
114



Cross-Section

Design criteria we have used 25yrs return period for our design purpose because our road
to be designed is DS4.

Step 2 Determining Hydrology using

Rational method equations yield

Q25=16.5m3/s, Q50=17.9m3/s

Step 3 Design Downstream Channel

Point Station, m Elevation, m

1 15+400 1346.3

2 15+410 1346.5

3 15+420 1346.7

4 15+430 1346.9

5 15+440 1346.9

6 15+450 1347.1

7 15+460 1347.2

8 15+470 1347.3

9 15+480 1347.4

10 15+490 1347.5

11 15+500 1347.6

Table 3-2 down stream station

Culvert Design-Example

X-Section At
Tail Water

115



Chainage Dist, m Level

15+400 0 1350.50

15+410 10 1350.30

15+420 20 1349.60

15+430 30 1348.00

15+440 40 1346.30

15+450 50 1348.20

15+460 60 1350.20

15+470 70 1352.00

15+480 80 1353.00

15+490 90 1354.20

15+500 100 1355.00

Table 3-3 X-Section At Tail Water

Step 3 Design downstream channel

0.00

116
v:h =1:2
ECSC, IUDS, Urban Engineering Department (UE) v:h =1:2

b=10m


The stream channel can be approximated to trapezoidal channel
B= 10m Slope 2:1 H:V
Channel material- clean straight, no rims or deep pools n =0.03
no sediment debris problem
Slope (s) 0.006
Table 3-4 Down stream chanal

The rating curve for the channel calculated by normal depth yields:

Width Q=AV,
Depth,m (B), m Area,m2 P, m R,m S N V=(1/n)R^2/3S^1/2 m3/s

0.10 10 1.02 12.24 0.08 0.006 0.03 0.49 0.50

0.30 10 3.18 12.24 0.26 0.006 0.03 1.05 3.34

0.50 10 5.50 12.24 0.45 0.006 0.03 1.52 8.33

0.70 10 7.92 12.24 0.65 0.006 0.03 1.93 15.29

117



0.73 10 8.30 12.24 0.68 0.006 0.03 1.99 16.55

0.76 10 8.70 12.24 0.71 0.006 0.03 2.06 17.91

0.90 10 10.62 12.24 0.87 0.006 0.03 2.35 24.95

1.00 10 12.00 12.24 0.98 0.006 0.03 2.55 30.58

1.05 10 12.71 12.24 1.04 0.006 0.03 2.65 33.64

1.10 10 13.42 12.24 1.10 0.006 0.03 2.75 36.85

1.20 10 14.88 12.24 1.22 0.006 0.03 2.94 43.77

1.50 10 19.50 12.24 1.59 0.006 0.03 3.52 68.69

1.700 10 22.78 12.24 1.86 0.006 0.03 3.91 89.01

Table 3-5 The rating curve for the channel calculated by normal depth yields:

Q (m3/s) TW (m) Elev,m asl Velocity(m/s)

0.5 0.1 1346.3 0.49

3.34 0.3 1346.5 1.05

8.33 0.5 1346.9 1.52

15.29 0.7 1346.9 1.93

16.55 0.73 1347.1 1.99

24.95 0.9 1347.2 2.06

30.58 1.0 1347.3 2.35

36.85 1.05 1347.3 2.55

Downstream

Q m3/s Depth,m Elev,masl

0.50 0.10 1346.3

3.34 0.30 1346.5

8.33 0.50 1346.7

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15.29 0.70 1346.9

16.55 0.73 1346.9

24.95 0.90 1347.1

30.58 1.00 1347.2

33.64 1.05 1347.3

36.85 1.10 1347.3

43.77 1.20 1347.4

68.69 1.50 1347.7

89.01 1.700 1347.9

Table 3-6 down stream rating curve

Step 5 Select Design Alternative

Shape - box Size - 3000 mm by 2000 mm

Material – concrete Entrance- Wingwalls, for 30o flare

Step 6 Select Design Discharge

Qd=16.5m3/5

Step 7 Determine Inlet Control Headwater Depth (HWi)

Use inlet control nomograph - Chart 7-6

a. D = 2 m

b. Q/B = 16.5/3 = 5.5

c. HW/D = 1.2, for 30o flare

d. HWi = (HW/D)*D

= (1.2)(2m)

= 2.4m (Neglect the approach velocity)

119



Step 8 Determine Outlet Control Headwater Depth at Inlet (HWoi)

a. TW =0.73 m for Q50 = 16.5 m3/s

b. dc = 1.43 m from Chart 7-7 (ERA design manual)

Or, by using the formula we obtain the critical depth as follows:

dc=0.467*(Q÷B)2/3

=0.467*(16.5÷3) 2/3

= 1.46m which is similar to the value obtained from the nomogragh in
previous case. So let us take our dc=1.43, so that

(dc + D)/2 = (1.43 + 2)/2 = 1.71 m

And, ho = max(TW , (dc + D/2)),but our Tw=0.73m from step 8 above

ho = (dc + D)/2 = 1.71 m =>maximum value of the two.

e. Ke = 0.2 from Table 7-2 ERA mannual

f .Determine (H) - use Chart 7-8 (ERA design manual)

 Ke scale = 0.2

 culvert length (L) = 80 m

 n = 0.012 same as on chart

 area = 6.0m2

 H = 0.67m (from nomogragh 7-8)

g. HWoi = H + ho - SoL = .67 + 1.71 - (0.006)80 = 1.9 m

HWoi is less than 1.2D, but control is inlet control, outlet control

120



computations are for comparison only

Step 9 Determine Controlling Headwater (HWc)

 HWc = HWi = 2.4 m > HWoi = 1.9

 The culvert is in inlet control

Step 10 Compute Discharge over the Roadway (Qr)

a. Calculate depth above the roadway:

HWr = HWc – Hwov

= 2.4 – (1352.9-1348)

= -2.5m (This result shows that there is no any water flowing over the road).In
other word the level of water is 2.5m below the roadway.

Step 11 Compute Total Discharge (Qt)

In our calculation above we have determined the discharge over the road is (Qt=0)
because it has negative value. So the total discharge (Qt) is calculated

As follows:

Qt = Qd + Qr = 16.5 m3/s + 0 = 16.5 m3/s

Step 12 Calculate Outlet Velocity (Vo) and Depth (dn)

Inlet Control

a. Calculate normal depth (dn):

Where we have used trial error method to calculate the normal depth of the flow in the
culvert

Q = (1/n)A* R2/3 S1/2 ,but A=B*dn,

where A=cross sectional area
121



B=width of the culvert

R=A/Pw, where A=cross sectional area

R=hydraulic radius of the culvert

Pw=wetted perimeter of the clvert

Pw=B+2dn ,B=3

16.5 m3/s= (1/0.012)(3*dn)[(3*dn)/(3+2dn)]2/3(0.05)0.5

= (3*dn)[3*dn/(3+2dn)]2/3 *(0.05)0.5

=>dn=1.08m as it is shown in the following table in order to convey the total
discharge (Qt=16.5). So our trials and their corresponding results are given in the table
below.

dn 1/n A R^2/3 S^1/2 V Q

0.2 83.33 0.60 0.3 0.1 2.2 1.3

0.25 83.33 0.75 0.4 0.1 2.5 1.9

0.3 83.33 0.90 0.4 0.1 2.8 2.5

0.4 83.33 1.20 0.5 0.1 3.2 3.9

0.50 83.33 1.50 0.5 0.1 3.6 5.4

0.90 83.33 2.70 0.7 0.1 4.8 12.8

1.00 83.33 3.00 0.7 0.1 5.0 14.9

1.05 83.33 3.15 0.7 0.1 5.1 15.9

1.08 83.33 3.24 0.7 0.1 5.1 16.6

1.10 83.33 3.30 0.7 0.1 5.1 17.0

1.15 83.33 3.45 0.8 0.1 5.2 18.1

122



1.20 83.33 3.60 0.8 0.1 5.3 19.2

1.50 83.33 4.50 0.8 0.1 5.8 25.9

2.00 83.33 6.00 0.9 0.1 6.3 37.7

2.20 83.33 6.60 0.9 0.1 6.5 42.6

2.30 83.33 6.90 0.9 0.1 6.5 45.1

2.50 83.33 7.50 1.0 0.1 6.7 50.1

2.60 83.33 7.80 1.0 0.1 6.7 52.6

3.00 83.33 9.00 1.0 0.1 7.0 62.7

Table 3-7 Discharge trial

From the table above we determined our dn =1.08m.

A = (3)*1.08 = 3.24 m2

Vo = Q/A = 16.5/3.24

= 5.093 m/s >2.5*1.99m/s (down stream velocity).So energy dissipater is required to
the damage of adjacent structure and to protect scouring outlet of culvert.

Step 13 Review Results

This step is the step of comparison of alternative design with constraints and
assumptions, if any of the following are exceeded we repeat, Steps 5 through 12 in order
to have a convenient and safe design.

 barrel has:

((1352.9-1346.2) m-2.4m) = 2.5m of cover

 L = 80m is OK, since inlet control

 headwalls and wing walls fit site

 allowable headwater (4.9 m) > 2.5 m is ok and

 overtopping flood frequency > 25-year
123



So the design is ok!

3.3.4 Structural Design of Culvert

The following principles are specific to structural design of culverts:

 All culverts shall be hydraulically designed.

 Overtopping flood selected is generally consistent with the class of highway and the
risk at the site

 Culvert location in both plan and profile shall be investigated to avoid sediment
build-up in culvert barrels.

 Material selection shall include consideration of materials availability, and the service
life including abrasion and corrosion potentials.
Design Criteria

Listed below by categories are the design criteria that should be considered for all culvert
designs. The type of drainage structure specified for a particular location is often
determined based on economic considerations; Culverts can be concrete box culverts,
reinforced concrete pipe culverts, or corrugated metal culverts; Concrete box culverts are
constructed with a square or rectangular opening, and with wing walls at both ends.

Design Computation

In this project we propose four culverts and one bridge based on the topography and the
flow direction.

Culvert 1 is at station =12+592.31m




Bridge 1 is at station =14+089m
124



For design purpose we took culvert number 4 at station15+471.12m as a sample for the
hydraulics and structural design of the culvert. We choose box culvert for our design
since it is easy to construction, to prevent scouring and settlement due to the soil type of
that area.

Fig 3-3 station of culvert 4

Structural design of box culvert

Design data

Geometric data

Internal dimension=h=2

W=3m… (From the hydraulics)

Height of fill above the culvert=4.6m (from the profile)

125



Thickness of the slab=300mm (thickness is normally taken

as 1/10th to 1/15th of the span)

External dimensions =h=2.3m and w=3.3m

Road width=6.7m

Span=3.3m

Concrete: take C25

Reinforcement

Take steel: S460

Geotechnical data

Unit weight of the soil =18kN/m3 (assumed)

Angle of repose of the soil, Ø=300 (assumed)

Design type

 A live load of design truck.
 Dead load, live load with water pressure from inside.
Design procedure

1/ Load

Dead load= (1*4.6) m*18kN/m3

=82.8KN/m2

2/ Tire contact area calculation:-

Contact area =L*w

Where w=500mm

126



L=2.28*10-3**(1+IM/100)*p

Where =load factor for the limit state under consideration

=1.75(ERA, table 3-2)

IM= dynamic load allowance percent

=33% for other limit state

P=72.5KN for design truck

There fore, L= 2.28*10-3*1.75*(1+.33/100)*72.5 =290mm.

Fig 3-4 wheel load distribution

Distribution of wheel load:-

For height of fill > 0.6m

L’=L+1.15hf

W’=w+1.15hf (ERA section 3.8.6)

There fore, L’=0.29+1.15*4.6 =5.58m

W’=0.50+1.15*4.6 = 5.79m

127



But L’ is greater than the span of the culvert. There fore the intensity of the live loading
needs to be reduced proportionally.

Reduced load= (72.5*3.6)/5.58 =46.77KN

Load with impact factor=1.25*46.77 =58.47KN

Intensity of live load on the slab:

Intensity=load/area

=load/ (culvert span*w’)

=58.47/ (3.6*5.79)=2.805KN/m2 =2805N/m2

3/ Load and reaction calculation

Dead load of the top slab:-

=0.3*1*25000=7500N/m2=75KN/m2

Total load on the culvert=Dead load +Live load

=82.8KN/m2+2.805kN/m2=85.605KN/m2=85605N/2

There fore,

Total design load on the top slab=85605N/2+7,500N/m2

=93,105N/m2

Weight of each wall (side wall) =2.3*0.3*25000=17,250N/m

Then, up ward reaction at the base

= [(93,105*3.3) + (2*17250)]/3.3*1

=103,559N/m2

128



4/ Lateral pressure

Coefficient of active pressure (Ka) =

1 − sin 30 1
Ka = =
1 + sin 30 3

Lateral pressure due to dead and live load

=Total vertical load*Ka =85605*1/3 =28535N/m2

Lateral pressure due to the soil at depth of 2.6m:

=Ka**h =1/3*18000*2.6=15600N.m2

There fore,

Lateral intensity at top=28535N/m2

Lateral intensity at the bottom=28535+15600N.m2 =44135N/m2

Fig 3-5 Pressure diagram for live and dead load

129



Fig3-5 Pressure diagram due to water

Fig 3-6 Final pressure diagram of the forces or loadings on the components of the culvert.

6/ Moments and shear force calculation

On account of symmetry, it is enough to consider half the frame AEFD for moment
distribution. As all members are of uniform thickness and have the same dimensions,
their moments of inertia are equal.
130



Relative stiffness of members is:

KAD=1

KAE=KDF=1/2

Distribution factors are:

1
1 2
D AD = DDA = = 1
1 3 ; D AB = DDC = 2 =
1+ 1 3
2 1+
2

Fixed end moments are:

wl 2 93105 * 2.6 2
MFAB = − = = −52449 N .m = −52.499 KN .m
12 12

wl 2 103559 * 3.6 2
MFDC = + = = +111843.7 N .m = +111.843KN .m
12 12

MFAD = +
pl 2 wl 28535 * 2.6 2
+ = +
( 12 * 2.6 *15574) * 2.6 = + 19584.06N .m = + 19.584KN .m
12 15 12 15

MFDA = −
pl 2 wl
− =−
28535 * 2.6 2
−
( 12 * 2.6 *15574) * 2.6 = − 21338.73N .m = − 21.338KN .m
12 10 12 10

Joint member D A

DC DA AD AB
131



DF 1/3 2/3 2/3 1/3

Fixed E.Mome.(KN.m) 111.8 -21.34 19.58 -52.49

balance -30.15 -60.31

-30.15

balance 42.04 21.02

carryover 21.01

balance -7. -14.01

carryover -7.005

balance 4.67 2.33

carryover 2.335

balance -0.778 -1.557

carryover -0.778

balance 0.519 0.259

carryover 0.259

balance -0.86 -0.173

carryover -0.086

balance 0.058 0.029

carryover 0.029

balance -0.01 -0.019

carryover -0.01

balance 0.007 0.003

carryover 0.003

balance -0.001 -0.002

Final end moments(KN.m) 73. -73. 28.85 -28.85

Then the final end moments are:-

132



MDC=73.001KN.m;

MDA=-73.77KN.m

MAD=28.83KN.m

MAB=-28.85KN.m

7/ Reactions

For horizontal slab AB, carrying distributed load of 93105N/m2,

Vertical reaction RA=RB is:-,

1
R A = RB = * 93105 * 3.6 = 167589 N
2

For bottom slab DC, carrying distributed load of 103559N/m2,

Vertical reaction RD =RC is:-

1
RD = RC = * 103559 * 3.6 = 186406.21N
2

For vertical member AD, the horizontal reaction HA at A is found by taking moments
about D. Thus,

( − H A * 2.6) + 28850 − 73000 +  28535 * 2.6 * 2.6  +  ( 44109 − 28835) * 2.6 * 2.6  = 0
   
 2   2.6 * 2 
H A = 29005.6 N

133



 28535 + 44109 
HD =  * 2 .6 − H A
 2 
= 94437.2 − 29055.6
= 65431.6 N

Fig3-7Shear force and axial forces

Bending moment calculation

93105 * 3.6 2
Free bending moment at mid point E = =150830.10 N.m
8

Then, net bending moment at E,(top slab)=150830.10-28850

=121980.10N.m

Again,

Free bending moment at mid point F (bottom slab) =

134



103559 * 3.6 2
= =167765.58 N.m
8

Then, net bending moment at F=167765.58-73000

=94765.58N.m

For vertical member AD, which is simply supported bending moment at mid span, is=

28535 * 2.6 2 ( 44109 − 28535) * 2.6 2
= +
8 16
= 30692.12 N.m

Then, net bending moment=

 73000 + 28850 
=  − 30692.12
 2 
= 20232.88 N.m

Components of the culvert Bending moment at the Bending moment at ends(N.m)
center(N.m)

Top Slab 121980.10 28850.00

Bottom slab 94765.58 73000.00

Side walls 20232.88 73000.00

Table3-8 Summary of bending moments of the culvert components

135



Fig3-8 Bending moment for the components of the culvert

Reinforcement

Overall depth=300mm

Cover=50mm

Effective depth=d=300-50=250mm

Fcd= (0.68*fck)/c= (0.68*25)/1.5=11.33MPa

fyd=fyk/1.15=460/1.15=400MPa

Width (b) =1000mm

Top slab

 At span/center
Depth checking

M
d check =
0.2952 * b * f cd

136



121980.10 *1000
d check = =190mm
0.2952 *1000 *11.33

There fore, the depth is adequate.

Area of steel (Ast,cal)=

 2M  f cd
Ast ,cal = 1 − * *b * d
 b * d 2 * f cd  f yd

 2 * 121980 * 1000  11.33
Ast ,cal = 1 − * * 1000 * 250
 1000 * 250 2 * 11.33  400
= 4641.65mm 2

Spacing(S) =

as * b
S=
As

=
(Π * 20 4 ) *1000 = 67.68mm
2

4641.65
Provide 20mm diameter bars with minimum c/c spacing 250mm.

 Support reinforcement

 2 * 28850 *1000  11.33
Ast ,cal = 1 − * *1000 * 250
 1000 * 250 2 *11.33  400
= 6504.25mm 2

as * b
Spacing ( S ) =
As

=
(Π * 20 4 ) *1000 = 48.30mm
2

6504.25


137



Bottom slab

 At span/center
Depth checking=

M
d check =
0.2952 * b * f cd

94765.58 *1000
d check = =168.33mm
0.2952 *1000 *11.33

There fore, the depth required is adequate.


 2M  f cd
Ast ,cal = 1 − 2 * *b*d
 b * d * f cd  f yd

 2 * 94765.58 *1000  11.33
Ast ,cal = 1 − * *1000 * 250
 1000 * 250 2 *11.33  400
= 5185.94mm 2

as * b
Spacing ( S ) =
As

=
(Π * 20 4 ) *1000 = 60.58mm
2

5185.94


 2 * 73000 * 1000  11.33
Ast ,cal = 1 − * * 1000 * 250
 1000 * 250 2 * 11.33  400
= 3865.88mm 2

138



as * b
Spacing ( S ) =
As

=
(Π * 20 4 ) *1000 = 81.26mm
2

3865.88


Side walls

 At span/center
Depth checking=

M
d check =
0.2952 * b * f cd

20232.88 *1000
d check = = 77.78mm
0.2952 *1000 *11.33

There fore, the depth required is adequate.


 2M  f cd
Ast ,cal = 1 − * *b*d
 b * d 2 * f cd  f yd

 2 * 20232.88 *1000  11.33
Ast ,cal = 1 − * *1000 * 250
 1000 * 250 2 *11.33  400
= 5388.48mm 2

Spacing(S) =

as * b
S=
As

=
(Π * 20 4 ) *1000 = 60.58mm
2

5388.48

139




 2 * 73000 * 1000  11.33
Ast ,cal = 1 − * * 1000 * 250
 1000 * 250 2 * 11.33  400
= 3865.88mm 2

as * b
Spacing ( S ) =
As

=
(Π * 20 4 ) *1000 = 81.26mm
2

3865.88


Section-4. Earth Work and Mass Haul Diagram

4.1 Earth Work

Earth work is conversion of natural ground condition to required sections and grades.
Earth work in high way design includes determination of cuts and fills, location of
borrow, waste sites, the free haul and over haul distance determination.

The careful attentions to limiting earthwork quantities through the preparation of a mass
haul diagram are essential elements in providing the best-combined horizontal, vertical,
and cross-sectional design. This is especially true when the design includes consideration
of the least cost in relation to earth works. Key terms associated with this process, as
listed in definitions, include:

Borrow - material not obtained from roadway excavation but secured by widening cuts,

flattening back slopes, excavating from sources adjacent to the road within the

Right-of-way, or from selected borrow pits as may be noted on the plans.

Waste - material excavated from roadway cuts but not required for making the

140



embankment.

Free Haul - the maximum distance through which excavated material may be transported

without the added cost above the unit bid price.

Overhaul - excavated material transported to a distance beyond the free haul distance.

Economic Limit of Haul - distance through which it is more economical to haul
excavated material than to waste and borrow.

Clearing and garbing (m2) - the removal of top soil, trees, bushes and e.t.c

Excavation (m3) - the process of loosing and removal of soil and rocks. It can be done
for three reasons.

 In order to maintain the grades for roads and drainage
 For structure foundation
 For borrow excavation
Embankment /compaction (m3k.hr) - densification of fill section of the road.

The steps involved in the computation of earthwork quantities and the development of the

optimal mass haul diagram are:

• End area calculations
• Earthwork calculations
• Preparation of mass haul diagram.
• Balancing earthworks using the mass haul diagram
Purpose of the preparation of earth work quantities and mass haul diagram

• To estimate cost of the (to limit the cost of construction)
• For the proper distribution of excavated material
• To determine amount and location of waste and borrow.
• Amount of over haul in kilometer cubic meter can be determined.

141



• To determine direction of haul.

Computation of earthwork

There are several ways of calculating earthwork but the most common is the average end

area method. This method consists of averaging the cut and fill quantities of adjacent

stations and multiplying by the distance between stations to produce cubic meters of

excavation and embankment between the two stations.

End Area Calculations

In this project we took 25 cross section that covers total distance of 500 m (from station
12 + 500 to 13+000 m)

Calculation procedure followed

 Area at different cross section along the road with an interval of 20m station
is taken.
 Read the elevations of existing profile along the right of way (50 m) from the
contour to plot the points.
 Design proposed carriage way by providing a cross fall of 2.5% from the
center to both direction. Then the amount of cut and fill are determined at
each 20m stations (to calculate the end area areas we use AutoCAD software
program)
 Preparation of mass haul diagram.
Volume calculation

The volume of earth work from the successive cross sections can be computed by
different formulas like average end area method, (trapezoidal method) or primordial
formula.

Average end Area Method (trapezoidal method)

142



 A1 + A2 
V=  * L
 2 

Where :

 V= volume in m3
 A1and A2 is area of successive cross-section in m2
 L= distance between successive cross section in m in this case 20 m.
The average end area method is simple and is generally preferred, so we choose this
method for this particular project.

The volume computed by this formula is likely to be higher than the true value in the case
of the section changing rapidly.

Estimation of earth work quantities

Based on:-

o Estimate of quantities
o Rate of abstract of work
Shrinkage and swelling should be included in estimating the quantities. According to
ERA 2001 there is a recommended shrinkage and swelling factor there fore the following
tables show the recommended values of Shrinkage factors

Type of soil Shrinkage factor

Light soil (ordinary ground) 10-25%

Light soil(swamp ground) 20-40%

Heavy soil up to10%

Table 4-1 Soil shrinkage factor

4.2 Mass haul diagram
143



It is a graphical representation of the amount of earth work and embankment involved in
a project and the manner in which the earth is to be moved.

The mass haul diagram shows excavation (adjusted) and embankment quantities from
some point of beginning on the profile, considering cut volumes positive and fill volumes

negative. At the beginning of the curve the ordinate is zero, and ordinates are calculated

continuously from the initial station to the end of the project.

Mass haul diagram is a continuous curve showing the accumulated algebraic sum of the
cut (+ve) and fill (-ve) volume from some initial station for any succeeding section. The
horizontal axis represents distance and is usually expressed in meters or stations. The
vertical axis represents the cumulative quantity of earth work in cubic meter (m3).

The mass haul diagram allows determining direction of haul and the quantity of earth
taken from or hauled to any location. It shows balance point the station between which is
the volume of excavation. In this project horizontal axis represents stations from 12+500
to 13+000 and the vertical axis represents the cumulative volume.

Use of mass haul diagram

The mass haul diagram can be used to determine:

 Proper distribution of excavated material
 Amount and location of waste
 Amount and location of borrow
 Amount of overhaul in kilometer-cubic meters
 Direction of haul.
 In proportion and enabling suitable plant, equipment or machinery.
For our project the mass haul diagram is drawn according to the following data. We use
swelling factor of 0 % and factor shrinkage 85 % because we assume the soil is ordinary
common soil so we consider only swelling.

Calculation of mass ordinates is performed and the results are shown below on the table.
144



145



End Area(m2) Dist
Mass
Station cut Fill ance(m) Adj.factor Adj.cut Tot.Adj.cut vol. fill vol. ordinet(m3)

12+500 15.64 48.35 0.85 13.29 0.00

12+520 11.95 81.06 20 0.85 10.16 234.49 1294.05 -1059.56

12+540 2.98 89.72 20 0.85 2.53 126.91 1707.81 -2640.46

12+560 0.00 125.60 20 0.85 0.00 25.34 2153.18 -4768.30

12+580 0.00 115.74 20 0.85 0.00 0.00 2413.38 -7181.68

12+600 0.24 79.78 20 0.85 0.21 2.08 1955.22 -9134.82

12+620 9.06 36.18 20 0.85 7.70 79.13 1159.64 -10215.34

12+640 2.35 43.15 20 0.85 2.00 97.05 793.37 -10911.67

12+660 60.34 0.86 20 0.85 51.29 532.86 440.18 -10818.99

12+680 95.33 0.00 20 0.85 81.03 1323.19 8.64 -9504.44

12+700 115.38 0.87 20 0.85 98.07 1791.02 8.74 -7722.15

12+720 123.29 6.48 20 0.85 104.80 2028.70 73.58 -5767.03

12+740 111.28 19.05 20 0.85 94.59 1993.91 255.35 -4028.47

12+760 108.40 29.66 20 0.85 92.14 1867.26 487.10 -2648.32

12+780 107.95 45.24 20 0.85 91.76 1838.95 748.97 -1558.34

12+800 151.88 50.51 20 0.85 129.10 2208.56 957.43 -307.21

12+820 99.01 76.88 20 0.85 84.16 2132.54 1273.84 551.49

12+840 104.34 78.86 20 0.85 88.69 1728.42 1557.42 722.49

12+860 95.42 82.83 20 0.85 81.11 1697.94 1616.97 803.47

12+880 82.88 101.51 20 0.85 70.45 1515.58 1843.46 475.59

12+900 72.19 101.21 20 0.85 61.36 1318.07 2027.19 -233.53

12+920 77.90 111.42 20 0.85 66.22 1275.74 2126.26 -1084.05

12+940 72.59 125.25 20 0.85 61.70 1279.14 2366.72 -2171.63

12+960 60.88 128.38 20 0.85 51.75 1134.47 2536.32 -3573.48

12+980 51.63 152.34 20 0.85 43.89 956.37 2807.19 -5424.30

13+000 49.85 165.54 20 0.85 42.37 862.60 3178.82 -7740.53

Table 4-2 mass ordinate
146



Fig.4-1 Mass haul diagram

The direction of haul:

 From station 12+640 to 12+740 to the left.
 From station 12+740 to 12+860 to the right.
Economical Over Haul Distance

When costing the Earth moving, there are basic costs which are usually included in the
contracts for the project.

Cost of free haul :- any earth moved over distances not greater than the free haul
distance is cost only on the excavation of its volume.

Cost of over haul: - any earth moved over distances greater than the free haul distance is
charged both for its volume and for the distance in excess of the free haul distance over
which it is moved. This charge can be specified either for units of haul or for units of
volume.

Cost of waste: - any surplus or unsuitable material which must be removed from the site
and deposited in a tip is usually charged on units of volume. This charge can vary from
one section of the site to another depending on the nearness of tips.

147



Cost of borrow: - any extra material which must be brought on to the site to make up the
deficiency is also usually charged on units of volume.

This charge can also vary from one section of the site to another depending on the
nearness of borrow pits.

ELH = FH distance + (Unit Price of Borrow/ Unit Price of Overhaul)
Where: ELH = Economic limit of haul

FH = Free haul distance

Assume that

 Ec = cost of excavation per unit volume(m3)
Hard excavation to embankment = 273 birr/m3
Excavation an unsuitable = 62 birr/m3
 Bc = cost of borrow per cubic meter per station = 15 birr/m3
 OHc = cost of over hauling per unit volume-station = 12 birr /m3
 FH = Free haul distance = 120m (6 station)
ELH = FH + (Bc / OHc)

= 120/20 + 15/12 = 7.25 station or 145 m

Therefore the economic haul distance is 145 m.

Total free haul volume = VD + FW

= 3500 +1500 =5000 m3 from mass haul diagram

Total borrow =AB + LH = 4000 +7800 = 11800m3

Cost of earth work = cost of borrow +cost of excavation + cost of over haul

Cost of borrow = Total volume of borrow *cost of borrow per meter cubic

=11800m3*15 birr/100m3 = 1770 birr

Cost of excavation = volume of excavation * cost of excavation per meter cubic
148



Volume of excavation = DJ + FI = 7000 +4900 = 11900m3

Cost of excavation = 11900*273 birr/100m3 =32,487 birr

Cost of over haul = over haul volume *cost of over haul per station meter.

For loop 1

Over haul volume 1 = area CJM + area UEO

= 43,750 + 70,000 = 113750 m3

For loop 2

Over haul volume 2 = area ESP+ area QRG

= 96,250 + 87,500 = 183,750 m3

Total Over haul volume = 113750 + 183,750 = 297,500 m3

Cost of over haul = 297,500 m3 *12 birr/100m3

= 35,700 birr.

Total cost of earth work = cost of borrow +cost of excavation + cost of over haul

= 1770 birr + 32,487 birr + 35,700 birr.

= 69,957 birr

Section-5: Pavement design
Pavement design is the process of developing the most economical combination of
pavement layers (thickness, type) to suit the soil foundation and withstand the load due to
cumulative traffic during the design life or period.

149



The design standard described here presents the pavement design standard which will be
utilized in the course of the design works all in accordance with ERA Pavement Design
manuals and other internationally recognized Pavement Design Standards. The main
design parameters for the pavement design include:

 Estimating the amount of traffic
 Assessing and evaluating the strength of sub grade soil
 Locally available construction materials
 Drainage Conditions
 Environment factors
In this standard, traffic volume, Sub grade type, construction materials and local factors
are the main design inputs.

The traffic volume will be determined from the traffic counts in terms of AADT
(Average Annual Daily traffic) we take this value from the given data. We determine the
Sub grade type and strength from the given CBR % (California Bearing Ratio) Values.

The basic idea in building a pavement for all-weather use by vehicles is to prepare a
suitable Sub grade, provide necessary drainage and construct a pavement that will:

 Have sufficient total thickness and internal strength to carry expected traffic
loads;
 Have adequate properties to prevent or minimize the penetration or internal
accumulation of moisture, and
 Have a surface that is reasonably smooth and skid resistant at the same time, as
well as reasonably resistant to wear, distortion and deterioration by weather.
The sub grade ultimately carries all traffic loads.

The basic idea in building a pavement for all weather use by vehicles is:

• To prepare a suitable sub grade
• Provide necessary drainage and

150



• Construct a pavement that will have sufficient total thickness and internal strength
to carry expected traffic loads, and distribute them over the sub grade soil without
overstressing.
Design inputs

In this pavement design, the design inputs are summarized into two main parameters,
traffic load in terms of cumulative ESA and Subgrade strength interim of CBR. The
overall required strength is read from charts or graphs which preset pavement catalogues
in which each pavement composition is classified based on ranges of traffic loading (T 1-
T8) and Subgrade strength (S1-S6) maximum CBR value. Therefore we provide flexible
pavement for our road project.

Flexible pavements

Flexible pavements are intended to limit the stress created at the sub grade level by the
traffic traveling on the pavement surface, so that the sub grade is not subject to significant
deformations. In effect, the concentrated loads of the vehicle wheels are spread over a
sufficiently larger area at sub grade level.

A flexible pavement is one, which has low (bending) flexural strength, and the load is
largely transmitted to the sub grade soil through the lateral distribution of stresses with
increasing depth.

The pavement thickness is designed such that the stresses on the sub grade soil are kept
with in its bearing capacity and the sub grade is prevented from excessive deformation.

The strength and smoothness of flexible pavement structure depends to a large extent on
the deformation of the sub grade soil.

A flexible pavement must satisfy a number of structural criteria or considerations;

 The sub grade should be able to sustain traffic loading without excessive
deformation; this is controlled by the vertical compressive stress or strain at this
level.

151



 Bituminous materials and cement-bound materials used in road base design
should not crack under the influence of traffic; this is controlled by the horizontal
tensile stress or strain at the bottom of the road base.
 The road base is often considered the main structural layer of the pavement,
required to distribute the applied traffic loading so that the underlying materials
are not over stressed. It must be able to sustain the stress and strain generated
within it with out excessive or rapid deterioration of any kind.
 In pavements containing a considerable thickness of bituminous materials, the
internal deformation of these materials must be limited; their deformation is a

function of their creep characteristics.

 The load spreading ability of granular sub base and capping layers must be
adequate to provide a satisfactory construction platform.
Elements of the conventional flexible pavement

Tack coat

 Is a very light application of asphalt usually asphalt emulsion diluted with water
used to ensure the bond between the surface being paved (surface course) and the
overlying course.
Essential requirements of tack coat

• It must be very thin.

• It must uniformly cover the entire surface to be paved.

• It must be allowed to break or cure before the HMA is laid.

Prime coat

 Is an application of low viscosity cut-back asphalt to an absorbent surface, such as
un treated granular base on which an asphalt layer will be placed.
 Its purpose is to bind granular base to the asphalt layer.

152



 The prime coat penetrates the underlying layer, plugs the voids, and forms water
tight surface.
Surface course

 The surface course is the top course of an asphalt pavement, sometimes called the
wearing course
 It is usually constructed by dense graded hot-mix asphalt
It must be:

 Tough to resist distortion under traffic and provide a smooth and skid-resistant
riding surface.
 Waterproof to protect the entire pavement and sub grade from the weakening
effect of water.
Binder course

 Sometimes called the asphalt base course is the asphalt layer below the surface
course.
It is placed for two reasons:

• First, the HMA is too thick to be compacted one layer, so it must be placed in two
layer.

• Second the binder course generally consists of larger aggregates and less asphalt
and does not require a high quality as the surface so replacing a part of the
surface course by the binder course results in a more economical design.

Base course

The base course is the layer of material immediately beneath the surface course.

It may be composed of well graded crushed stone (unbounded), granular material
mixed with binder, or stabilized materials. It is the main structural part of the
pavement and provides a level surface for laying the surface layer.

Sub base course
153



Construct using local and cheaper materials for economic reason on top of the
sub grade. It provides additional help to the base and the upper layers in
distributing the load. It facilitates drainage of free water that might get
accumulated below the pavement.

Sub grade

It is the foundation on which the vehicle load and the weight of the pavement
layers finally rest. It is an in situ or a layer of selected materials compacted to the
desirable density near the optimum moisture content.

Fig 5-1 Road layer

The basic key elements for designing of pavements are:

• Traffic class
154



• Sub grade strength

5.1 Traffic volume analysis

Traffic classes are depends on ESAs & vehicle classification;

Where ESAs are based on:

 Vehicle classification
 Cumulative traffic volume ( T )
 Equivalency factor (EF)
Vehicle classification from the give data

Passenger vehicles Freight vehicles

Cars Small trucks

4WD Medium trucks

Small bus Heavy trucks

Large bus Articulated trucks

Cumulative traffic volume ( T )

T = AADT1*(p)*(D)*365((1+i)N -1)/i

Where, AADT1 traffic volume when the road is open (2013)

i = growth rate = 7 %, it is given

N = design period = 15, it is given

P = lane distribution factor =1 (100%) ERA/AASHTO

D = directional distribution factor = 0.5 this accounts for any
directional variation in total traffic volume or loading pattern.

Equivalency factor (EF)

155



EF= (Axle i/8160)n

Where, n is usually 4.5

Axles i = load in kg

 The Cumulative number of vehicles are depends on AADT (2013) & Diverted
traffic (2013), then we use the sum of both traffic volume.
 To calculate equivalent standard axles (ESAs) by using, Cumulative number of
vehicle (T) and Equivalency factor (EF).
5.2 Axle load survey and equivalent factor computation

From the axle load survey data of each vehicle, the equivalent factor is computed and
summarized in the following table. Refer to annex for the detail computation.

Day 13 Day 14 Day 15 Day 16 Day 17 Day 18 T0TAL
Classificatio
n of vehicles NO. EF NO. EF NO. EF NO. EF NO. EF NO. EF NO. EF EF

car 0.00

4 WD 0.00

0.3 0.5 0.5 0.7
S/Bus 10 0.3 10 1 10 4 10 4 10 0.44 10 5 60 2.87 0.05

8.8 3.8 10.
L/Bus 10 8.3 10 9 10 9 10 10 10 8.90 10 9 60 50.86 0.85

S/Truck 5 0.0 5 0.02 0.00

0.9 0.0 3.8 0.1
M/Truck 10 0.3 10 1 10 9 10 6 10 6.02 10 6 60 11.28 0.19

55. 46. 49. 91.4 58. 385.0
L/Truck 10 83.3 10 5 10 7 10 8 10 0 10 4 60 2 6.42

192. 145. 878.3
T/Trailer 10 6 10 165 10 117 10 145 10 5 10 112 60 9 14.64

5.3 Traffic class determination

156



Calculation of ESAs by using the above Axle load survey

EF= (Axle i/8160)^4.5 T = AADT1*(p)*(D)*365((1+i)N -1)/i

i= 7% P= 1 D= 0.5

Day 13 Day 14 Day 15 Day 16 Day 17 Day 18 T0TAL Cumula.
Classification No. ESAs
of vehicles NO. EF NO. EF NO. EF NO. EF NO. EF NO. EF NO. EF EF AADT1 Veh. (10^6)

car 0.00 0 0 0.00

4 WD 0.00 21 96307 0.00

0.3 0.5 0.5 0.7
S/Bus 10 0.3 10 1 10 4 10 4 10 0.44 10 5 60 2.87 0.05 18 82549 0.00

8.8 3.8 10.
L/Bus 10 8.3 10 9 10 9 10 10 10 8.90 10 9 60 50.86 0.85 7 32102 0.03

S/Truck 5 0.0 5 0.02 0.00 38 174270 0.00

0.9 0.0 3.8 0.1
M/Truck 10 0.3 10 1 10 9 10 6 10 6.02 10 6 60 11.28 0.19 31 142167 0.03

55. 46. 49. 91.4 58. 385.0
L/Truck 10 83.3 10 5 10 7 10 8 10 0 10 4 60 2 6.42 51 233888 1.50

192. 145. 878.3 14.6
T/Trailer 10 6 10 165 10 117 10 145 10 5 10 112 60 9 4 38 174270 2.55

Sum 4.11

Table 5-1 ESAs computation

ESAs = 4.11*10^6

Based on this traffic analysis the main access belongs to the traffic class T 5 which is in the
range of (3 to 6)*10^6 ESAs.

CBR test from the given data is 4% from 0 km to 24km and our road project is between
12.5 km to 15.5 km. According to ERA 2002 design manual CBR test (3-4) % fails in to
the soil class sub grade strength S2 .Therefore our road project design is based on traffic
class T5 and sub grade strength S2.

5.4 Selection of economical section

157



By using T5 and S2 the economical pavement selected from the catalog of pavement types
and configuration for design of road section. Chart (1, 2, 3, 4, 7 and 8) selected for
comparison purpose.

pric(m3)inbi
Materials abbreviation rr

Double surface dressing DSD 1000

Flexible bituminous surface FBS 2050

Bituminous surface BS 900

Bituminous road base, RB BRB 1045

Granular road base, GB1-GB3 GRB(1-3) 560

Granular sub base GS GSB 250

Granular capping layer, or selected sub grade fill, GC GCL or SSF 200

Cement or lime stabilized road base1, CS1 C or LSRB1

Cement or lime stabilized road base2, CS2 C or LSRB2 810

Cement or lime stabilized sub base, CS C or LSSB 860

Table 5-2 Material and price

Chart 1 Chart 2

SD SD

158



Chart 3 Chart 4

Chart 7 Chart 8

SD

159



160



THICKNESS OF THE CHARTS (mm) Price Price (Birr )

Materials chart1 chart2 chart3 chart4 chart7 chart8 Birr/m3 chart1 chart2 chart3 chart4 chart7 chart8

DSD 50 50 50 1000 50 50 50

FBS 50 50 50 2050 102.5 102.5 102.5

BRB 125 1045 130.63

GRB(1-3) 200 150 175 150 560 112 84 98 84

GSB 275 275 225 250 68.75 68.75 56.25

GCLorSSF 200 200 200 200 200 225 200 40 40 40 40 40 45

CorLSRB2 250 225 200 810 202.5 182.25 162

CorLSSB 225 860 193.5

Total 270.75 376.5 309.25 408.75 329.38 400.5

Table 5-3 Economical section

161



From the above charts, chart 1 is more economical than others but it is not technically
feasible, because mostly it is used for maintenance purpose. Therefore, we choose chart 3
with bituminous surface (HMA). The thickness of each layer summarized as follows:

Materials Layer
thickness(mm)
Station(km)

FBS 50

GRB(1-3) 175
12 +500- 15+ 500
GSB 275

GCL or SSF 200

Table 5-4 selected section

Section-6: Provision of traffic controls

Signings and Markings

They are directly related to the design of the highway or street and futures of traffic
control’s and operation that the designer should consider in the geometric layout of such
facilities. The potential for future operational problems can be significantly reduced if
signing and marking are treated as an integral part of the highway design.

The extent to which signs and markings are used depends on the traffic volume, type of
facility and the extent of traffic control appropriate for save and efficient operation.

Generally highway signs are three types as per AASHTO practice

• Regulatory signs: to indicate the rules for traffic movement (prohibitory and
mandatory).
Mandatory signs for stop and yielding.

Prohibitory signs for curve movements, weight and speed limitation etc

162



• Warning or danger or cautionary signs: to indicate conditions that may involve
risk to highway users.
• Guide or information signs: to direct traffic along a route or towards a distention.
Physical obstructions in or near our road way project should be removed in order to
provide the appropriate clear zone. Where removal is impossible, such objects should be
adequately marked by painting or by use of other highly visible material.

Where the object is in the direct line of traffic, the obstruction and marking there on
preferably should be illuminated at night by flood lighting; where there is not practical,
the object markings should be effectively reflectorized.

Post mounted delineators are another type of marking devises used to guide traffic,
particularly at night. Reflector units are installed at certain height & spacing to delineate
the road way where alignment changes may be confusing & not clearly defined.

The importance of traffic control devices

• Give timely warning of hazardous situation when they are not self evident
• Regulating traffic by imparting messages to the drivers about the need to
stop, give way or yielding & limit their speed
• Give information as to highway routes, directions & point of intersection.
The general guide lines for the provision of traffic signings

• It should be installed only by the authority of law with proper enforcement
measures to respecting the signs.
• It should be provided only after traffic engineering studies & sound judgments.
• Excessive use of signs should not be resorted to.
• They should be legible & understood to those who using it (visibility, lettering,
symbols, locations, simplicity, uniformity & standard size).
Location, height & maintenance of traffic signs

The location, reflecting & lighting of signs are important considerations.

163



The signs should be located on the risk side of the road where the drivers will be looking
at them. On hill roads, they should be fixed on the valley side of the road & mounted on
the posts. According to AASHTO practice the signs in rural areas shall be mounted at a
height of at least 1.5m measured from the bottom to the pavement.

The sign posts should be maintained in proper position & legible at all time. Damaged
signs should be replaced immediately. Periodic painting of signs should be a routine part
of maintenance.

Road markings provisions

These markings are used as a means of controlling & guiding traffic of roads & safety.

These are:

• Carriage way marking-which includes center line strip, traffic line strip, no over
taking zone, stop lines , pedestrian &cyclist crossings , route directions etc.
• Object markings-which should contains Krebs markings, culvert head wall
markings, & other objects adjacent to the carriage way.
The general guide lines of longitudinal pavement markings

• Solid lines are restrictive & cannot be crossed.
• Broken lines are restrictive in character & vehicle can cross it safely.
• Double lines indicate maximum restrictions.
• When combination of solid & broken lines are used, and the traffic moves to the
right(left), a vehicle should not cross the continuous line adjacent to the
right(left) of broken lines on the lane which the vehicle moving.
• Pavement marking colors shall be white (optional crossing) & yellow (not
crossing).
On rural areas the center line marking of the pavement segment & gaps shall be doubled
in length than an urban location, due to less traffic congestions. In addition the length of
gaps shall be shorter near approaches, intersections & on curves than on straight reaches.
The gap shall be half the value on straight sections.

164



Traffic lane lines

The division of the carriage way in to separate lanes for traffic traveling in the same
directions on either side of the center line or median strip helps to promote travel in
proper lanes by promoting safety & ensuring maximum capacity.

No overtaking zone marking

These markings shall be provided on summit curves, horizontal curves & tangents in two
or three lane highways where overtaking & passing maneuvers must be prohibited,
because of non availability of safe overtaking sight distance or other hazardous
conditions. The marking for “No overtaking” zone consists of a combination lines along
the center line. The combination lines consist of a double line, the left hand element of
which shall be a solid barrier line & the right hand element also either a normal broken
center line or solid barrier governing the traffic from the opposite direction. Where a olid
barrier line is to the right of the broken line, the overtaking restriction shall apply only to
the opposing the traffic. If both lines are solid lines, “No overtaking” is permitted in both
directions.

165



Fig 6-1. For areas on which “No overtaking” is permitted in both directions.

Fig.6-2 a normal broken center line for areas on which passing is permitted safely in both
directions.

166



Fig.6.3 solid barrier line & the right hand element broken center line for areas on which
a solid barrier line is to the right of the broken line, the overtaking restriction in one
direction

Pavement edge lines or strips

These shall be used to indicate the edges of carriageway on which no Krebs are provided.

They serve as a visual guidance for the drivers, indicating to them the limits up to which
the driver can safely venture. They especially are useful during adverse weather & poor
visibility. Where the paved shoulder is of a lesser structural strength than the main
pavement, the edge lines are used to promote travel on the main pavement itself.

Edge lines shall be in the form of single continuous lines placed about 15cm from the
edge & the width of the lines shall be 15-20cm. Based on the above guide lines &
principles as per AASHTO & ERA manuals we recommended that:

• On the crest curve, from station (PC)=13+472 to (PT) =
13+672 “overtaking” is not permitted hence the solid barrier
marking lines along with center line must be provided. In
addition to this post mounted traffic signs that show ascent or
descent summit curve must be provided on the risk side of
the road.
• On horizontal curves, from PC=12+655.43 to
PT=12+774.55, from PC=13+098.59 to PT=13+199.38,
PC=13+263.38 to PT=13+445.38, from PC=13+806.5 to
PT=14+180.50, from PC=14+685.72 to 14+820.57, and from
PC= 15+175.76 to PT=15+274.96 , here also “overtaking” is
not permitted therefore the solid barrier marking lines along
with center line must be provided. And post mounted traffic
signs that show speed limitation, to the right hand & to the

167



left hand horizontal curve sign must be provided on the risk
side of the road & visible to the traffic.
• On the tangent curve, from station (PT) = 12+774.55 to
station (PC) =13+098.59, similar manner as to horizontal
curves.
Section-7: Environmental consideration

Environmental assessment: the identification and evaluation of the likely effects of a
proposed policy, program, or project on the environment; alternatives to the proposal;
measures to be adopted to protect the environment; a standard tool for decision making.

Environmental Issues Include

• Noise from all types of equipment and traffic
• Air quality / emissions and dust problems from all types of equipment and traffic
• Impact on natural and planted vegetation: removal or trimming of only those plants
and trees directly affected by the implementation of the Project will be permitted.
• Provisions for pedestrians and non-motorized traffic.
• Access to properties /access to the site
• Soil stability and earthworks
• Effect on watercourses and water quality
• Effects on adjacent land.
• Material disposal
• Equipment operation and disposal
• Disposal of waste and reinstatement of land
Therefore the above factors will considered during construction of this project.

Erosion

When natural conditions are modified by the construction of a road, it marks the start of a
race between the appearance of erosion and the growth of vegetation. Disturbance during
construction can upset the often delicate balance between stabilizing factors, such as
168



vegetation, and others which seek to destabilize, such as running water. In some cases
erosion might result in cumulative impacts far beyond the road itself, affecting slopes,
streams, rivers, and dams at some distance from the initial impact.

Side-tipping of spoil materials

Spoil material from road cuttings can kill vegetation and add to erosion and slope
stability problems. Large amounts of spoil can be generated during construction in
mountainous terrain. Sometimes it is difficult to design for balances between cut and fill
volumes of earth at each location, and haulage to disposal sites may be expensive. This
creates a need for environmental management of tipped material.

During construction we shall not interrupt or interfere with the flow of irrigation waters
without making prior arrangements with and obtaining the agreement of the irrigation
authorities. The contractor shall allow in his program for the construction of those works
which might interface with the flow of irrigation waters to be carried out at such times as
will cause the least disturbance to irrigation operations.

The contractor shall comply with the following: Meet the requirements of regulations.
Consult, with the engineer before locating and constructing project offices and sheds and
installing construction plant. Prevent pollution of any kind to adjacent property resulting
from the construction operation. Sites containing cement, line and similar items shall be
suitably protected from rain and flood. Natural streams or channels adjacent to the works
of this contract shall not be disturbed without the approval of the engineer.

Management of Waste Materials
Management of waste materials: all excavated material to be disposed off-site in
locations approved by the local regulatory agency. No material is to be disposed down
slope without specific approval of the site engineer, and will be approved only if existing
drainage, agricultural land, housing, and slope stability is not affected. All waste oils to
be disposed of in accordance with existing environmental regulations.

Remedial Measures

169



Prevention

When planning new roads or changes in width or alignment, sensitive natural
environments should be identified early in the planning process so that alternate routes
and designs may be considered. Wherever possible, road developments should be located
more than one kilometer away from sensitive areas to avoid severe impacts on flora and
fauna. Water crossings should be minimized, and buffer zones of undisturbed vegetation
should be left between roads and after courses. Groundwater recharge areas should be
avoided, and major roads should not be constructed through national parks or other
protected areas. Advantage should be taken of opportunities to twin new road corridors
with previously established transport rights-of-way, such as railway lines.

Animal crossings

As we know Somale region has a lot of camel and goat and other wild animal .Animal
crossings can be used to assist the migration of these animals. At important crossing
points, animal tunnels or bridges have sometimes been used to reduce collision rates,
especially for protected or endangered species. Tunnels are sometimes combined with
culverts or other hydraulic structures. These measures are expensive and used only at a
few locations where they are both justified (by the importance of the animal population
and the crossing route) and affordable (relative to the cost of the project and the funds
available.

170



Annexes

Annexe-1 terrain classification data

station Elv.diff.(m) H.distance(m) Slope (%) Terrain Remarks
classification

12+500 10 64.62 15.48 Rolling

12+520 12 49.09 24.44 Rolling

12+540 12 44.14 27.19 Mountainous

12+560 16 72.95 21.93 Rolling

12+580 16 61.61 25.97 Mountainous

12+600 20 88.62 22.57 Rolling

12+620 22 104.2 21.11 Rolling

12+640 24 109.36 21.95 Rolling

12+660 24 94.49 25.40 Mountainous

12+680 24 96.69 24.82 Rolling

12+700 26 109.72 23.70 Rolling

171



12+720 26 115.4 22.53 Rolling

12+740 26 111.19 23.38 Rolling

12+760 26 106.85 24.33 Rolling

12+780 28 106.19 26.37 Mountainous

12+800 30 110.63 27.12 Mountainous

12+820 30 107.58 27.89 Mountainous

12+840 30 108.26 27.71 Mountainous

12+860 28 100.08 27.98 Mountainous

12+880 28 102.46 27.33 Mountainous

12+900 28 107.74 25.99 Mountainous

12+920 26 114.21 22.77 Rolling

12+940 26 95.19 27.31 Mountainous

12+960 24 85.46 28.08 Mountainous

12+980 24 92.68 25.90 Mountainous

13+000 20 76.43 26.17 Mountainous

13+020 22 89.62 24.55 Mountainous

13+040 28 101.46 27.60 Mountainous

13+060 26 92.29 28.17 Mountainous

13+080 26 92.76 28.03 Mountainous

13+100 24 97.52 24.61 Rolling

13+120 26 118.78 21.89 Rolling

13+140 24 104.16 23.04 Rolling

13+160 26 136.26 19.08 Rolling

13+180 26 116.46 22.33 Rolling

13+200 26 104.63 24.85 Rolling

13+220 26 95.84 27.13 Mountainous

13+240 26 103.46 25.13 Mountainous

172



13+260 26 98.53 26.39 Mountainous

13+280 24 91.86 26.13 Mountainous

13+300 20 112.18 17.83 Rolling

13+320 4 99.49 4.02 Rolling

13+340 8 115.2 6.94 Rolling

13+360 10 126.58 7.90 Rolling

13+380 12 101.27 11.85 Rolling

13+400 12 100.37 11.96 Rolling

13+420 14 105.34 13.29 Rolling

13+440 16 104.77 15.27 Rolling

13+460 18 99.32 18.12 Rolling

13+480 22 112.79 19.51 Rolling

13+500 22 103.12 21.33 Rolling

13+520 24 100.46 23.89 Rolling

13+540 26 102.99 25.25 Mountainous

13+560 26 93.67 27.76 Mountainous

13+580 26 86.25 30.14 Mountainous

13+600 30 98.06 30.59 Mountainous

13+620 30 92.25 32.52 Mountainous

13+640 28 80.12 34.95 Mountainous

13+660 28 75.52 37.08 Mountainous

13+680 28 72.91 38.40 Mountainous

13+700 30 81.44 36.84 Mountainous

13+720 32 98.29 32.56 Mountainous

13+740 32 103.67 30.87 Mountainous

13+760 32 102.5 31.22 Mountainous

13+780 32 104.98 30.48 Mountainous

173



13+800 32 93.3 34.30 Mountainous

13+820 32 104.76 30.55 Mountainous

13+840 30 128.59 23.33 Rolling

13+860 30 135.71 22.11 Rolling

13+880 30 145.89 20.56 Rolling

13+900 28 145.95 19.18 Rolling

13+920 28 141.63 19.77 Rolling

13+940 26 152.86 17.01 Rolling

13+960 22 153.32 14.35 Rolling

13+980 20 131.94 15.16 Rolling

14+000 16 115.77 13.82 Rolling

14+020 14 107.45 13.03 Rolling

14+040 12 96.56 12.43 Rolling

14+060 8 45.36 17.64 Rolling

14+080 8 30.59 26.15 Mountainous

14+100 4 41.6 9.62 Rolling

14+120 4 24.73 16.17 Rolling

14+140 8 42.08 19.01 Rolling

14+160 8 54.93 14.56 Rolling

14+180 8 58.2 13.75 Rolling

14+200 10 76.44 13.08 Rolling

14+220 10 67.47 14.82 Rolling

14+240 12 69.23 17.33 Rolling

14+260 12 62.82 19.10 Rolling

14+280 12 63.81 18.81 Rolling

14+300 14 72.11 19.41 Rolling

14+320 14 71.83 19.49 Rolling

174



14+340 14 70.36 19.90 Rolling

14+360 14 72.4 19.34 Rolling

14+380 12 65.94 18.20 Rolling

14+400 12 66.38 18.08 Rolling

14+420 12 65.11 18.43 Rolling

14+440 12 64.56 18.59 Rolling

14+460 12 64.36 18.65 Rolling

14+480 12 66.09 18.16 Rolling

14+500 12 65.26 18.39 Rolling

14+520 12 65.94 18.20 Rolling

14+540 12 68.3 17.57 Rolling

14+560 12 67.52 17.77 Rolling

14+580 12 68.97 17.40 Rolling

14+600 12 69 17.39 Rolling

14+620 12 62.41 19.23 Rolling

14+640 12 61.49 19.52 Rolling

14+660 12 61.43 19.53 Rolling

14+680 12 60.15 19.95 Rolling

14+700 12 58.29 20.59 Rolling

14+720 14 83.74 16.72 Rolling

14+740 14 85.15 16.44 Rolling

14+760 14 101.46 13.80 Rolling

14+780 12 90.01 13.33 Rolling

14+800 12 95.51 12.56 Rolling

14+820 14 110.72 12.64 Rolling

14+840 14 108.07 12.95 Rolling

14+860 14 105.75 13.24 Rolling

175



14+880 14 103.65 13.51 Rolling

14+900 14 100.27 13.96 Rolling

14+920 14 94.31 14.84 Rolling

14+940 14 87.69 15.97 Rolling

14+960 14 81.65 17.15 Rolling

14+980 14 79.81 17.54 Rolling

15+000 16 96.04 16.66 Rolling

15+020 16 93.13 17.18 Rolling

15+040 16 88 18.18 Rolling

15+060 16 85.64 18.68 Rolling

15+080 16 83.05 19.27 Rolling

15+100 16 78.25 20.45 Rolling

15+120 16 76.14 21.01 Rolling

15+140 16 74.54 21.46 Rolling

15+160 16 73.3 21.83 Rolling

15+180 16 71.11 22.50 Rolling

15+200 16 62.19 25.73 Mountainous

15+220 16 61.9 25.85 Mountainous

15+240 16 62.19 25.73 Mountainous

15+260 16 60.52 26.44 Mountainous

15+280 16 60.96 26.25 Mountainous

15+300 12 59.21 20.27 Rolling

15+320 12 67.21 17.85 Rolling

15+340 10 61.63 16.23 Rolling

15+360 8 55.67 14.37 Rolling

15+380 8 71.14 11.25 Rolling

15+400 6 55.63 10.79 Rolling

176



15+420 4 35.66 11.22 Rolling

15+440 6 89.63 6.69 Rolling

15+460 6 99.54 6.03 Rolling

15+480 8 86.28 9.27 Rolling

15+500 6 59.36 10.11 Rolling

Annexe-2 Natural ground profile and the finished road grade elevation

177


Grade Grade
Station Natu. Elevation Station Natu. Elevation
Elevation Eleation

12+500 Design Senior Project
Highway 1384.30 1386.00 13+360 1398.60 2010
1393.60

12+520 1384.50 1386.18 13+380 1398.00 1393.80

12+540 1384.30 1386.36 13+400 1396.70 1393.98

12+560 1384.50 1386.53 13+420 1395.30 1394.16

12+580 1384.30 1386.71 13+440 1394.20 1394.33

12+600 1385.00 1386.89 13+460 1394.00 1394.51

12+620 1386.10 1387.06 13+480 1394.00 1394.67

12+640 1387.30 1387.24 13+500 1393.40 1394.73

12+660 1388.40 1387.42 13+520 1393.00 1394.68

12+680 1389.50 1387.60 13+540 1393.00 1394.51

12+700 1390.20 1387.77 13+560 1392.50 1394.23

12+720 1390.30 1387.95 13+580 1391.80 1393.84

12+740 1390.30 1388.13 13+600 1390.50 1393.34

12+760 1390.00 1388.31 13+620 1390.00 1392.73

12+780 1389.90 1388.48 13+640 1389.50 1392.00

12+800 1390.10 1388.66 13+660 1388.90 1391.18

12+820 1389.70 1388.84 13+680 1387.70 1390.24

12+840 1389.00 1389.01 13+700 1386.00 1389.28

12+860 1389.00 1389.19 13+720 1385.40 1388.32

12+880 1388.80 1389.37 13+740 1385.00 1387.30

12+900 1388.60 1389.55 13+760 1385.00 1386.40

12+920 1388.90 1389.72 13+780 1384.00 1385.40

12+940 1388.60 1389.90 13+800 1383.50 1384.50

12+960 1388.40 1390.01 13+820 1384.10 1383.59

12+980 1387.70 1390.26 13+840 1385.40 1382.63

13+000 1387.50 1390.43 13+860 1384.50 1381.76

13+020 1387.00 1390.61 13+880 1384.00 1380.96

13+040 1387.00 1390.79 13+900 1382.10 1380.21

13+060 1387.30 1390.96 13+920 1380.23 1379.53

13+080 1387.20 1391.14 13+940 1379.00 1378.89
178
13+100 1387.90 1391.32 13+960 1376.00 1378.34
13+120 1389.00 1391.50 13+980 1374.30 1377.80

13+140 1389.80 1391.67 14+000 1373.50 1377.34


Station Natural Grade Station Natural Grade
Elevation Elevation
Elevation Elevation

14+220 1377.60 1375.90 14+880 1367.50 1367.20

14+240 1378.00 1376.00 14+900 1367.60 1366.70

14+260 1378.20 1376.10 14+920 1367.00 1366.20

14+280 1378.10 1376.20 14+940 1366.30 1365.70

14+300 1378.20 1376.30 14+960 1365.90 1365.25

14+320 1378.10 1376.35 14+980 1365.70 1364.80

14+340 1377.80 1376.40 15+000 1365.60 1364.30

14+360 1377.80 1376.51 15+020 1365.60 1363.80

14+380 1377.30 1376.56 15+040 1365.60 1363.30

14+400 1377.20 1376.57 15+060 1365.00 1362.80

14+420 1378.00 1376.53 15+080 1365.00 1362.30

14+440 1376.40 1376.45 15+100 1364.90 1361.80

14+460 1376.10 1376.32 15+120 1365.00 1361.30

14+480 1375.60 1376.14 15+140 1363.90 1360.80

14+500 1375.30 1375.91 15+160 1363.70 1360.30

14+520 1375.00 1375.64 15+180 1363.80 1359.85

14+540 1374.40 1375.31 15+200 1363.00 1359.40

14+560 1374.20 1374.94 15+220 1363.00 1358.70

14+580 1373.60 1374.53 15+240 1362.40 1358.40

14+600 1373.00 1374.08 15+260 1359.60 1357.90

14+620 1372.10 1373.60 15+280 1357.80 1357.40

14+640 1371.30 1373.10 15+300 1356.00 1356.90
179



14+660 1370.80 1372.60 15+320 1354.40 1356.40

14+680 1369.80 1371.10 15+340 1353.80 1355.90

14+700 1369.50 1371.60 15+360 1352.20 1355.40

14+720 1369.40 1371.10 15+380 1351.90 1354.90

14+740 1369.00 1370.64 15+400 1351.90 1354.45

14+760 1369.00 1370.20 15+420 1351.90 1353.96

14+780 1368.50 1369.70 15+440 1349.90 1353.47

14+800 1368.00 1369.20 15+460 1346.00 1353.00

14+820 1368.10 1368.70 15+480 1351.00 1352.59

14+840 1367.90 1368.20 15+500 1353.00 1352.00

14+860 1367.70 1367.70

180



Annexe-3 Nomograph

181



Anexe-4 Axle load survey and EF computation

182



Traffic count for day 13, Small Bus

axle1 axle2 Axle EF1 Axle EF2 Total EF

SB (25) 3300 3350 0.017 0.018 0.035

SB (14) 1150 1650 0.000 0.001 0.001

SB (25) 1800 2850 0.001 0.009 0.010

SB (25) 2250 3850 0.003 0.034 0.037

SB (25) 2300 3800 0.003 0.032 0.035

SB (25) 2250 4000 0.003 0.040 0.043

SB (25) 2350 3000 0.004 0.011 0.015

SB (25) 2400 3800 0.004 0.032 0.036

SB (25) 2350 3050 0.004 0.012 0.016

SB (25) 2400 4400 0.004 0.062 0.066

Sum 0.295

Large Bus

axle1 axle2 axleEF1 Axle EF2 Total EF
183



LB (45) 3800 6200 0.032 0.291 0.323

LB (45) 4400 6600 0.062 0.385 0.447

LB (45) 3350 5400 0.018 0.156 0.174

LB (60) 6000 7450 0.251 0.664 0.915

LB (45) 3850 7050 0.034 0.518 0.552

LB (45) 4350 6000 0.059 0.251 0.310

LB (62) 7000 9150 0.502 1.674 2.176

LB (62) 5450 9600 0.163 2.078 2.240

LB (45) 4050 7450 0.043 0.664 0.707

LB(45) 3550 6750 0.024 0.426 0.449

Sum 8.292

Medium truck

axle1 axle2 axle3 axleEF1 axleEF2 Axle EF3 Total EF

MT 2850 5400 0.009 0.156 0.000 0.165

MT 1600 1350 0.001 0.000 0.000 0.001

MT 1700 1550 0.001 0.001 0.000 0.001

MT 2200 3300 0.003 0.017 0.000 0.020

MT 1500 1600 0.000 0.001 0.000 0.001

MT 2300 2500 0.003 0.005 0.000 0.008

MT 2450 2250 0.004 0.003 0.000 0.007

MT 2850 3700 0.009 0.028 0.000 0.037

MT 1800 1600 0.001 0.001 0.000 0.002

MT 1600 2700 0.001 0.007 0.000 0.008

Sum 0.250

Large truck

axle1 axle2 axle3 axle4 Axle EF1 Axle EF2 Axle Axle Total

184



EF3 EF4 EF

LT 6450 15950 0.35 20.41 0.00 0.00 20.756

LT 4200 5250 0.05 0.14 0.00 0.00 0.188

LT 6050 14200 0.26 12.10 0.00 0.00 12.358

LT 5950 11800 0.24 5.26 0.00 0.00 5.500

LT 6250 14300 0.30 12.49 0.00 0.00 12.787

LT 8250 9900 9850 1.05 2.39 2.33 0.00 5.770

LT 8950 10700 10750 1.52 3.39 3.46 0.00 8.358

LT 4800 8950 0.09 1.52 0.00 0.00 1.607

LT 7000 13000 0.50 8.13 0.00 0.00 8.632

LT 5900 12600 0.23 7.06 0.00 0.00 7.297

Sum 83.253

Truck trailer

axle1 axle2 axle3 axle4 axle5 axle6 axle axle EF2 axle axle axle axle totalEF

185



EF1 EF3 EF4 EF5 EF6

1525 1100
TT 6050 0 0 11400 0.26 16.68 3.83 4.50 0.00 0.00 25.27

1500
TT 6300 0 8350 9450 0.31 15.48 1.11 1.94 0.00 0.00 18.84

1460
TT 6350 0 7950 9150 0.32 13.71 0.89 1.67 0.00 0.00 16.60

1480
TT 5900 0 8750 9750 0.23 14.57 1.37 2.23 0.00 0.00 18.40

1320
TT 5750 0 8300 7100 0.21 8.71 1.08 0.53 0.00 0.00 10.53

1140 1160 1310
TT 6150 0 0 11300 0 0.28 4.50 4.87 4.33 8.42 0.00 22.40

1580
TT 6950 0 7750 9500 0.49 19.56 0.79 1.98 0.00 0.00 22.82

1700
TT 2350 0 8050 9200 0.00 27.19 0.94 1.72 0.00 0.00 29.85

1360
TT 6850 0 9150 9150 0.45 9.96 1.67 1.67 0.00 0.00 13.76

1100 1100 1010
TT 6450 0 0 10800 0 0.35 3.83 3.83 3.53 2.61 0.00 14.16

Sum 192.63

186



Traffic count for day 14,Small Bus

Axle1 Axle2 Axle1 Ef Axle2 EF Total EF

SB (25) 2300 3450 0.003 0.021 0.024

SB (25) 2250 2500 0.003 0.005 0.008

SB (25) 2350 3700 0.004 0.028 0.032

SB (25) 2250 4400 0.003 0.062 0.065

SB (25) 2200 3950 0.003 0.038 0.041

SB (25) 1750 2800 0.001 0.008 0.009

SB (25) 2200 3250 0.003 0.016 0.019

SB (25) 2300 3500 0.003 0.022 0.026

SB (25) 2550 4300 0.005 0.056 0.061

SB (25) 2150 3550 0.002 0.024 0.026

Sum 0.311

Large Bus


LB (45) 2100 5950 0.002 0.241 0.244

LB (45) 4150 7550 0.048 0.705 0.753

LB (62) 4600 7900 0.076 0.864 0.940

LB (62) 6600 9200 0.385 1.716 2.101

LB (62) 6600 9200 0.385 1.716 2.101

LB (62) 4000 6700 0.040 0.412 0.452

LB (45) 3900 5800 0.036 0.215 0.251

LB (45) 3400 6000 0.019 0.251 0.270

LB (62) 5300 8250 0.143 1.051 1.194

LB (45) 4200 7100 0.050 0.535 0.585
187



Sum 8.890

Medium truck


MT 1700 1850 0.001 0.001 0.002

MT 3650 3200 0.027 0.015 0.042

MT 3150 2250 0.014 0.003 0.017

MT 3250 3300 0.016 0.017 0.033

MT 2800 6650 0.008 0.398 0.406

MT 3250 2700 0.016 0.007 0.023

MT 1700 1150 0.001 0.000 0.001

MT 1850 1400 0.001 0.000 0.002

MT 2600 5950 0.006 0.241 0.247

MT 2750 5150 0.007 0.126 0.134

Sum 0.906

Large truck

Axle1 Axle2 Axle3 Axle4 Axle5 Total
Axle1 Axle2 Axle3 Axle4 Axle5 Ef EF EF EF EF EF

LT 4350 7700 7650 0.06 0.77 0.75 0.00 0.00 1.58

LT 4800 8400 9850 11050 11250 0.09 1.14 2.33 3.91 4.24 11.72

LT 7750 10500 10950 0.79 3.11 3.76 0.00 0.00 7.66

LT 4100 2950 2900 0.05 0.01 0.01 0.00 0.00 0.06

LT 7600 11200 11300 0.73 4.16 4.33 0.00 0.00 9.21

LT 7000 12100 9050 0.50 5.89 1.59 0.00 0.00 7.98

LT 5200 5300 0.13 0.14 0.00 0.00 0.00 0.28

LT 4100 3800 0.05 0.03 0.00 0.00 0.00 0.08

LT 5750 15250 0.21 16.68 0.00 0.00 0.00 16.88

LT 3650 3550 0.03 0.02 0.00 0.00 0.00 0.05

188



Sum 55.50

Truck trailer

Axle1 Axle2 Axle3 Axle4 Axle5 Axle6 Total
Axle1 Axle2 Axle3 Axle4 Axle5 Axle6 Ef EF EF EF EF EF EF

TT 4100 4550 2700 2550 0.05 0.07 0.01 0.01 0.00 0.00 0.13

TT 5350 10850 11050 8900 9250 0.15 3.60 3.91 1.48 1.76 0.00 10.90

TT 7800 12950 10050 8150 9400 0.82 7.99 2.55 0.99 1.89 0.00 14.25

TT 6050 14600 9250 9100 0.26 13.71 1.76 1.63 0.00 0.00 17.36

TT 8450 11600 11650 11000 7200 7900 1.17 4.87 4.96 3.83 0.57 0.86 16.27

TT 6650 10950 11500 10500 13300 0.40 3.76 4.68 3.11 9.01 0.00 20.96

TT 6500 15000 8300 8700 0.36 15.48 1.08 1.33 0.00 0.00 18.25

TT 5200 16300 10300 10600 0.13 22.50 2.85 3.25 0.00 0.00 28.73

TT 5200 16000 9700 11000 0.13 20.70 2.18 3.83 0.00 0.00 26.84

TT 7900 13100 9400 6500 0.86 8.42 1.89 0.36 0.00 0.00 11.53

Sum 165.22

Traffic count for day 15,Small Bus


SB (25) 3450 5050 0.021 0.115 0.136

SB (25) 4000 4450 0.040 0.065 0.106

SB (25) 2150 3850 0.002 0.034 0.037

SB (25) 2400 3900 0.004 0.036 0.040

SB (25) 2200 4150 0.003 0.048 0.050

SB (25) 2200 4150 0.003 0.048 0.050

SB (25) 2450 4050 0.004 0.043 0.047

SB (25) 2550 4050 0.005 0.043 0.048

SB (25) 2050 2650 0.002 0.006 0.008

SB (25) 2300 2900 0.003 0.010 0.013

189



Sum 0.536

Large Bus


LB(45) 4400 7100 0.062 0.535 0.597

LB(24) 2300 3350 0.003 0.018 0.022

LB(45) 3600 6850 0.025 0.455 0.480

LB (45) 3750 5100 0.030 0.121 0.151

LB (45) 4250 7200 0.053 0.569 0.622

LB (45) 3600 4250 0.025 0.053 0.078

LB (45) 3900 5600 0.036 0.184 0.220

LB (45) 3650 5150 0.027 0.126 0.153

LB (45) 6050 7400 0.260 0.644 0.904

LB (45) 3950 7350 0.038 0.625 0.663

3.890

Medium truck


MT 2800 2050 0.008 0.002 0.010

MT 2150 3700 0.002 0.028 0.031

MT 2150 3400 0.002 0.019 0.022

MT 1900 2150 0.001 0.002 0.004

MT 2800 2050 0.008 0.002 0.010

MT 1850 2400 0.001 0.004 0.005

MT 1750 1700 0.001 0.001 0.002

MT 2250 1850 0.003 0.001 0.004

MT 1600 1200 0.001 0.000 0.001

MT 1750 1450 0.001 0.000 0.001

0.0907

190



Large truck


LT 8000 11800 0.91 5.26 0.00 0.00 0.00 0.00 6.17

LT 4400 3800 0.06 0.03 0.00 0.00 0.00 0.00 0.09

LT 4900 3600 3650 0.10 0.03 0.03 0.00 0.00 0.00 0.15

LT 6200 12300 0.29 6.34 0.00 0.00 0.00 0.00 6.63

1180 1095
LT 8200 11800 0 0 6950 7750 1.02 5.26 5.26 3.76 0.49 0.79 16.57

LT 5950 15100 0.24 15.95 0.00 0.00 0.00 0.00 16.19

LT 4800 4750 0.09 0.09 0.00 0.00 0.00 0.00 0.18

LT 5250 5200 0.14 0.13 0.00 0.00 0.00 0.00 0.27

LT 5500 3700 3500 3000 2100 0.17 0.03 0.02 0.01 0.00 0.00 0.23

LT 4350 4900 0.06 0.10 0.00 0.00 0.00 0.00 0.16

Sum 46.66

191



Truck trailer


TT 5800 4200 2450 2600 2350 1400 0.22 0.05 0.00 0.01 0.004 0.0004 0.28

TT 6300 14500 8400 8650 0.31 13.29 1.14 1.30 0.00 0.00 16.04

TT 8250 16300 11200 9300 1.05 22.50 4.16 1.80 0.00 0.00 29.51

TT 4150 4850 3100 3100 0.05 0.10 0.01 0.01 0.00 0.00 0.17

TT 3750 5250 3100 3150 0.03 0.14 0.01 0.01 0.00 0.00 0.19

TT 6900 10300 7900 6600 0.47 2.85 0.86 0.38 0.00 0.00 4.57

TT 7900 11950 11900 11300 8050 7850 0.86 5.57 5.46 4.33 0.94 0.84 18.00

TT 4050 5100 2950 3050 0.04 0.12 0.01 0.01 0.00 0.00 0.19

TT 5650 15900 9400 10500 0.19 20.12 1.89 3.11 0.00 0.00 25.31

TT 5350 15400 8400 11300 0.15 17.43 1.14 4.33 0.00 0.00 23.04

117.3

192



193



Traffic count for day 16

Small Bus

Axle1 Axle2 Axle3 Axle1 Ef Axle2 EF Axle3 EF Total EF

SB (25) 1600 2850 0.001 0.009 0.000 0.009

SB (25) 2300 3300 0.003 0.017 0.000 0.020

SB (25) 2250 4250 0.003 0.053 0.000 0.056

SB (25) 2100 3950 0.002 0.038 0.000 0.040

SB (25) 2300 3250 0.003 0.016 0.000 0.019

SB (25) 2250 4050 0.003 0.043 0.000 0.046

SB (25) 2200 4150 0.003 0.048 0.000 0.050

SB (25) 4000 5700 0.040 0.199 0.000 0.239

SB (25) 2450 3550 0.004 0.024 0.000 0.028

SB (25) 1950 3750 0.002 0.030 0.000 0.032

Sum 0.541

194



Large Bus


LB (45) 3850 6400 0.034 0.335 0.369

LB (45) 4150 6400 0.048 0.335 0.383

LB (45) 3900 6900 0.036 0.470 0.506

LB (62) 6100 7650 0.270 0.748 1.018

LB (45) 3750 7450 0.030 0.664 0.694

LB (62) 4850 9950 0.096 2.441 2.537

LB (45) 5500 10550 0.169 3.177 3.347

LB (45) 3500 6350 0.022 0.324 0.346

LB (45) 4300 6500 0.056 0.359 0.415

LB (45) 2850 6700 0.009 0.412 0.421

10.036

Medium truck

Axle1 Axle2 Axle4 Axle5
Axle1 Axle2 Axle3 Axle4 Axle5 Ef EF Axle3 EF EF EF Total EF

MT 1850 1600 0.001 0.001 0.000 0.000 0.000 0.002

MT 2750 5550 0.007 0.176 0.000 0.000 0.000 0.184

MT 1950 2300 0.002 0.003 0.000 0.000 0.000 0.005

MT 4600 10200 3800 3300 3450 0.076 2.730 0.032 0.017 0.021 2.875

MT 2200 3550 0.003 0.024 0.000 0.000 0.000 0.026

MT 4450 6800 0.065 0.440 0.000 0.000 0.000 0.506

MT 3000 4500 0.011 0.069 0.000 0.000 0.000 0.080

MT 1850 5150 2800 0.001 0.126 0.008 0.000 0.000 0.135

MT 2550 4000 0.005 0.040 0.000 0.000 0.000 0.046

MT 2250 1850 0.003 0.001 0.000 0.000 0.000 0.004

3.863

195



Large truck


LT 4150 5250 0.048 0.137 0.000 0.185

LT 7300 10850 10800 0.606 3.604 3.530 7.740

LT 6000 13600 0.251 9.961 0.000 10.212

LT 7700 16300 0.770 22.503 0.000 23.273

LT 4350 4250 0.059 0.053 0.000 0.112

LT 4350 4300 0.059 0.056 0.000 0.115

LT 5950 7600 7600 0.241 0.726 0.726 1.694

LT 4400 4600 0.062 0.076 0.000 0.138

LT 7800 11750 0.816 5.159 0.000 5.975

LT 4850 6150 0.096 0.280 0.000 0.376

49.821

Truck trailer

Axle1 Axle2 Axle3 Axle4 Axle5 Axle6 EF EF EF EF EF EF EF

TT 5150 3450 3700 3500 3650 0.13 0.02 0.03 0.02 0.03 0.00 0.22

TT 5950 13550 9550 8800 0.24 9.80 2.03 1.40 0.00 0.00 13.47

TT 7650 11900 11900 11400 7000 8200 0.75 5.46 5.46 4.50 0.50 1.02 17.70

TT 7850 15000 9850 9950 0.84 15.48 2.33 2.44 0.00 0.00 21.10

TT 7500 11900 11800 11200 6600 8550 0.68 5.46 5.26 4.16 0.38 1.23 17.18

TT 5550 13250 9600 11500 0.18 8.86 2.08 4.68 0.00 0.00 15.80

TT 5300 15800 9400 10300 0.14 19.56 1.89 2.85 0.00 0.00 24.44

TT 5850 14700 8850 9350 0.22 14.14 1.44 1.85 0.00 0.00 17.65

TT 5300 4350 3100 3300 0.14 0.06 0.01 0.02 0.00 0.00 0.23

TT 6200 14800 7950 9250 0.29 14.57 0.89 1.76 0.00 0.00 17.51

145.30

196



Traffic count for day 17 ; Small Bus


SB (25) 2250 3800 0.003 0.032 0.035

SB (25) 2500 4800 0.005 0.092 0.097

SB (25) 2550 4150 0.005 0.048 0.053

SB (25) 2550 4400 0.005 0.062 0.067

SB (25) 2200 4100 0.003 0.045 0.048

SB (25) 2600 3750 0.006 0.030 0.036

SB (25) 2250 4250 0.003 0.053 0.056

SB (25) 1500 2750 0.000 0.007 0.008

SB (25) 2450 3600 0.004 0.025 0.030

SB (25) 2250 2700 0.003 0.007 0.010

0.440

Large Bus


LB (45) 2350 3550 0.0037 0.0236 0.0273

LB (45) 4050 6700 0.0428 0.4118 0.4546

LB (60) 4250 7550 0.0531 0.7049 0.7581

LB (45) 3800 4800 0.0321 0.0918 0.1239

LB (45) 3850 7400 0.0340 0.6441 0.6781

LB (62) 5750 10000 0.2070 2.4969 2.7038

LB (45) 3650 7400 0.0268 0.6441 0.6708

LB (45) 3850 5700 0.0340 0.1990 0.2330

LB (45) 4400 6900 0.0621 0.4701 0.5322

LB (62) 7250 9650 0.5874 2.1270 2.7144

8.8963

197



Medium truck


MT 2750 9600 0.007 2.078 2.085

MT 2250 1800 0.003 0.001 0.004

MT 2200 1850 0.003 0.001 0.004

MT 2650 3700 0.006 0.028 0.035

MT 2550 4700 0.005 0.084 0.089

MT 2700 2100 0.007 0.002 0.009

MT 3650 9700 0.027 2.177 2.204

MT 3900 8850 0.036 1.441 1.477

MT 3400 4700 0.019 0.084 0.103

MT 2100 2350 0.002 0.004 0.006

6.016

Large truck


LT 2650 2050 0.006 0.002 0.000 0.008

LT 6400 14350 0.335 12.683 0.000 13.018

LT 5800 17050 0.215 27.552 0.000 27.767

LT 6200 15750 0.291 19.282 0.000 19.573

LT 5600 3450 3550 0.184 0.021 0.024 0.228

LT 6150 14400 0.280 12.883 0.000 13.163

LT 7000 8350 9150 0.502 1.109 1.674 3.285

LT 7450 12500 12350 0.664 6.815 6.455 13.934

LT 5600 4700 0.184 0.084 0.000 0.267

LT 4900 4250 0.101 0.053 0.000 0.154

Sum 91.3984

Truck trailer
198



Axle1 Axle2 Axle4 Axle5 Total
Axle1 Axle2 Axle3 Axle4 Axle5 Ef EF Axle3 EF EF EF EF

TT 4050 4650 2650 2650 0.04 0.08 0.01 0.01 0.00 0.14

TT 5150 3650 3750 3250 3400 0.13 0.03 0.03 0.02 0.02 0.22

TT 8750 14400 10100 11000 1.37 12.88 2.61 3.83 0.00 20.70

TT 6550 14050 8800 9400 0.37 11.53 1.40 1.89 0.00 15.20

TT 4500 4350 2350 2450 0.07 0.06 0.00 0.00 0.00 0.14

TT 6150 15400 8000 8900 0.28 17.43 0.91 1.48 0.00 20.10

TT 6600 13750 8550 9400 0.38 10.47 1.23 1.89 0.00 13.97

TT 6950 12300 11700 11800 11400 0.49 6.34 5.06 5.26 4.50 21.65

TT 6850 12350 11800 10450 10700 0.45 6.45 5.26 3.04 3.39 18.60

TT 7700 16200 10500 13300 0.77 21.89 3.11 9.01 0.00 34.78

145.48

Traffic count for day 18; Small Bus


SB (25) 2150 4250 0.002 0.053 0.056

SB (25) 2450 4000 0.004 0.040 0.045

SB (25) 2250 4050 0.003 0.043 0.046

SB (25) 2150 3500 0.002 0.022 0.025

SB (25) 3350 6000 0.018 0.251 0.269

SB (25) 2050 3900 0.002 0.036 0.038

SB (25) 3350 5450 0.018 0.163 0.181

SB (25) 2200 3900 0.003 0.036 0.039

SB (25) 1500 2750 0.000 0.007 0.008

SB (25) 2400 4000 0.004 0.040 0.044

Sum 0.750

Large Bus

199




LB (62) 6000 7450 0.251 0.664 0.915

LB (45) 4350 6450 0.059 0.347 0.406

LB (45) 3850 5900 0.034 0.232 0.266

LB (45) 4000 7650 0.040 0.748 0.788

LB (45) 4050 6150 0.043 0.280 0.323

LB (62) 5850 5800 0.224 0.215 0.439

LB (45) 5750 10750 0.207 3.457 3.664

LB (45) 5000 9450 0.110 1.936 2.046

LB (45 5150 8350 0.126 1.109 1.235

LB (62) 3800 7700 0.032 0.770 0.802

Sum 10.885

Medium truck


MT 1300 1350 0.0003 0.0003 0.001

MT 2500 4800 0.0049 0.0918 0.097

MT 1850 1750 0.0013 0.0010 0.002

MT 1850 1850 0.0013 0.0013 0.003

MT 2400 1650 0.0041 0.0008 0.005

MT 2300 3150 0.0034 0.0138 0.017

MT 2400 2450 0.0041 0.0045 0.009

MT 1950 1350 0.0016 0.0003 0.002

MT 2350 3250 0.0037 0.0159 0.020

MT 1750 1400 0.0010 0.0004 0.001

Sum 0.155

Large truck

200




LT 6450 14500 0.347 13.291 0.000 13.638

LT 7300 13300 0.606 9.010 0.000 9.616

LT 5000 8700 8700 0.110 1.334 1.334 2.779

LT 3300 2900 0.017 0.010 0.000 0.027

LT 4350 4280 0.059 0.055 0.000 0.114

LT 6300 14600 0.312 13.708 0.000 14.020

LT 6700 1000 10500 0.412 0.000 3.110 3.522

LT 7850 12000 0.840 5.672 0.000 6.512

LT 7200 11700 0.569 5.061 0.000 5.630

LT 4350 8550 8550 0.059 1.234 1.234 2.527

Sum 58.384

Truck trailer (TT)


TT 7450 14550 9400 9150 0.66 13.50 1.89 1.67 0.00 0.00 17.73

TT 4150 4250 2200 2200 0.05 0.05 0.00 0.00 0.00 0.00 0.11

TT 4050 4050 2950 3200 2800 3450 0.04 0.04 0.01 0.01 0.01 0.02 0.14

TT 7200 13300 9100 9850 0.57 9.01 1.63 2.33 0.00 0.00 13.55

TT 4150 4800 2800 2950 0.05 0.09 0.01 0.01 0.00 0.00 0.16

TT 7600 13200 8600 8550 0.73 8.71 1.27 1.23 0.00 0.00 11.94

TT 6350 16200 10800 10800 0.32 21.89 3.53 3.53 0.00 0.00 29.27

TT 4250 4250 2300 2250 0.05 0.05 0.00 0.00 0.00 0.00 0.11

TT 5550 15050 10300 10800 0.18 15.71 2.85 3.53 0.00 0.00 22.27

TT 4600 10750 10650 11800 11700 0.08 3.46 3.31 5.26 5.06 0.00 17.17

Sum 112.44

Part –II

Drawings
201



202


Highway design raport(final) (group 2)

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