1

Highway Engineering
(5th Level) &
Roads and Bridges
(4th Level)

Er. Sabin Pokhrel

Er. Sabin Pokhrel

 10.0 Highway Engineering
2

10.1. Introduction to Transportation System

Q. Define Transportation. What are the modes of
transportation ? (1+2)
❖ Movement of people and goods from one place to

another place with safe, easy, comfort, economical

is known as transportation.
❖ Movement of people is known as passenger
transportation whereas movement of goods is
known as freight transportation.
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3

Modes of Transportation
There are two (2) modes of transportation:
(I) Primary Modes of transportation
(II) Secondary Modes of transportation

(I) Primary Modes of Transportation:

Primary modes of transportation are of four(4 ) types:
(A) Landways:
(a) Roadways: Roads, Highway,Street
(Bus,Car,truck,motorcycle, etc)
(b) Railways: Rails (Wagon,train,container)

Er. Sabin Pokhrel

4

(B) Waterways: River,Lake,sea,ocean

(Ship,Boat,etc)
(C) Airways : Air-route (Plane,Aircraft,Helicopter)
(D) Spaceways: Space-route (Satellite,Rocket)

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5
Modes of Transportation…
(II) Secondary Modes of transportation:
➢ Secondary modes of transportation are of four(4 )

types:
(A) Ropeways: Cable (car,carriage,cabin,

chair,gondola)
(B) Pipeline: Pipe (Water,gas,sewer)

(C) Canal : Irrigation canal (Water)

(D) Belt Conveyor : Belt (Aggregate in crusher plant)

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6

Q. Movement of ……… from one place to another

place with safe, easy, comfort, economical is known
as transportation.
(a) People (b)Goods
(c) Both (a) & (b) (d) None of above

Er. Sabin Pokhrel

 Questions
7

Q. Which of the following is Fixed facility ?

(a) Bus

(b) Car

(c) Both (a) & (b)

(d) Highway

Q Which of the following is Flow entity ?

(a) Bus

(b) Car

(c) Both (a) & (b)

(d) Highway

Er. Sabin Pokhrel

 Questions
8

Q. Which modes of transportation provides door to door

service?
(a) Airways

(b) Waterways

(c) Roadways
(d) Railways

Q. Xm Which modes of transportation is feasible (

Appropriate or best ) in case of Nepal?
(a) Waterways (b) Railways
(c) Airways (d) Roadways
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9

Xm Q. Which of the following is fastest modes of

transportation:
(a) Roadways (350) (b) Waterways (150)
(c) Railways (603) (d) Airways (3600)
Q. Which of the following is fastest modes of
transportation:
(a) Roadways (b) Waterways
(c) Airways (d) Spaceways
(28000)

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10

Q. Xm Which of the following is cheapest modes of

transportation ?
(a) Roadways (b) Railways
(c) Waterways(Shipping) (d) Airways
Q. Which of the following is expensive modes of
transportation ?
(a) Roadways (b) Railways
(c) Waterways (d) Airways

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11

Q. Which of the following organization is responsible

for giving road permit in Nepal?
(a) DOR (b) DOTM
(c) CAAN (d) Municipality
Note:
DOR = Department of Roads
DOTM = Department of Transport Management
CAAN = Civil Aviation Authority of Nepal

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12

Q. Which of the following organization is responsible

for giving air permit in Nepal?
(a) DOR (b) DOTM
(c) CAAN (d) Municipality
Q. Which of the following organization is responsible
for road construction in Nepal?
(a) DOR (b) DOTM
(c) CAAN (d) Municipality

Er. Sabin Pokhrel

 Road Transport
13

Q. What are the advantages and dis-advantages of road

transportation ? (5 marks)
Answer: The advantages of road transportation are:
➢ It covers wide geographical coverage.

➢ It provides large Influential area.

➢ It provides door to door service.

➢ It is flexible in using it.

➢ It provides Quick and assured deliveries of goods.

➢ It provides highest employment potential before

construction, during construction and after construction.
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14
Advantages…
➢ It provides personalized travel and services.
➢ It is economical for short distance travel.
➢ It is safer in comparison with other modes of transportation.

The Dis-Advantages of road transportation are :

➢ It degrades the land.

➢ It creates environmental pollution.

➢ It consumes huge quantity of non-renewable sources of energy.

➢ It creates the problem of parking a lot.

➢ Repeated number of accident occurs daily.

➢ It is uneconomical for long distance travel.

Er. Sabin Pokhrel

 Explain about the historical
Development of Road Construction in
15
Nepal. (5 marks)
➢ During Rana regime, there were two offices named
“Batokaj Goswara” and “Chhembhadel Adda” for
road works and other civil engineering Construction
works respectively.
➢ There were branch office named “ Banaune Adda”
in other parts of the country.
➢ In 1918 AD, “Nayabatokaj Goswara” office was
established for the construction of new road and the
name of Batokaj Goswara was changed to “Purano
Batokaj Goswara”

Er. Sabin Pokhrel

 Historical Development of Road Construction in
Nepal…
16

➢ The main responsibilty of “Purano Batokaj

Goswara” was to look after the maintenance of
existing road.
➢ An Army Unit “Samarjung” was used to carry out
routine maintenance under “Purano Batokaj
Goswara”
➢ The new and old office were merged into one as
Public Work Directive (PWD) in 1950 AD.
➢ PWD had two sections named as Normal road and
bridge section.
Er. Sabin Pokhrel
 Historical Development of Road Construction in
Nepal…
17

➢ In 1970 AD (2027 B.S.), PWD was split into

separate department named as “Department of
Road” and “Department of Building”
➢ In 1956 AD, Tribhuvan Highway was constructed.
➢ In 1963 AD, Araniko Highway was constructed.
➢ In 1964 AD, Siddhartha highway was constructed.
➢ In 1993 AD, 6 regional office and 25 division office
of DOR were created.

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18

Tribhuwan Highway:
(I) First Highway of Nepal OR
(II) First Highway of Nepal Connecting India OR
(III) First Highway of Nepal Connecting Foreign

Country.
➢ Tribhuwan Highway was constructed by India in
1956 AD.

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19

Araniko Highway:
➢ First Highway of Nepal Connecting China

➢ Araniko Highway was constructed by China in 1963

AD.

Er. Sabin Pokhrel

 Classification of Road in Nepal
20

NRS : Nepal Road Standard (2027 B.S., 2045 B.S. and

latest is 2070 B.S.)
NRRS : Nepal Rural Road Standard ( 2055 B.S., 2069 B.S.
and latest is 2071 B.S.)
NURS : Nepal Urban Road Standard- 2076 B.S.
❖ NRS is used for the design of Strategic road
(Highway+ Feeder Roads), District road, Urban road.
❖ NRRS is used for the design of Rural road, Agricultural
road, Village road, etc.
❖ NURS is especially used for the design of Urban road.

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21

Xm. Q For the design of Rural road, which standard is used?

(a) NRS (c) IRC
(b) NRRS (d) Local standard
Q For the design of Urban road, which standard is used?
(a) NURS (c) IRC
(b) NRRS (d) Local standard
Q For the design of Urban road, which standard is used?
(a) NRS (c) Both of above
(b) NURS (d) IRC
IRC : Indian Road Congress

Er. Sabin Pokhrel

 Classification of Road in Nepal
22

Q. Explain about the classification of road in Nepal as

per NRS-2070 ? (5 marks) PSC-2080 B.S.
Answer:
❖ As per NRS-2070, road in Nepal is classified into two
types:
(I) Administrative Classification and
(II) Functional /Technical Classification
(I) Administrative Classification
❖ As per Administrative classification , there are four (4)
types of road and they are:

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23

(A) National Highway/Highway/Trunk Road

➢ The road along the length of the country or across the
width of the country is known as Highway.
➢ The important or major road of a country is Highway.
➢ National Highway are designated by Capital Letter “NH”
followed by two digit number. (Xm-Gandaki,5th,2080)
➢ Eg: NH01 = Mahendra Rajmarga (1028 km) , from Mechi
bridge, Jhapa Border to Gaddachowki Border,
Kanchanpur.
➢ There are 80 numbers of National Highway in Nepal.
➢ Tribhuwan Highway is the oldest of Nepal’s Highway.
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24
Administrative Classification…
(B) Feeder Roads:
➢ The road departing from Highway and connecting
to Zonal Headquarter, District Headquarter,
Economic centre or tourism area is known as feeder
roads.
➢ Feeder roads are designated by Capital Letter “F”
followed by three digit number.
➢ Eg: F001 = Birtamod to Chandragadhi
,Bhadrapur,12.53 km
➢ There are 208 numbers of Feeder roads in Nepal.

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25

(C) District Road

➢ The roads within the district is known as District
road.
➢ District roads are represented by capital letter
“DR”
 District Roads are important roads within a district
serving areas of production and markets, and
connecting with each other or with the main
highways.
 There are 77 District roads in Nepal.

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Q. District roads are represented by:

(a) Dr

(b) dr

(c) DR

(d) All of the above

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(D) Urban Roads

➢ The roads within the metropolitan city, sub-metropolitan
city, municipality or town development board is known
as Urban roads.
➢ Urban road are specially also known as street

➢ A roughly circumferential roads build around an Urban

areas is known as Ring Road
➢ The length of Inner ring road of Kathmandu valley is 27
km. (NH39)
➢ The length of Proposed Outer ring road of Kathmandu
valley is 68 km. (NH38)

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28

(II) Functional /Technical Classification(4 types)

(1) Class-I (Expressway)
❖ Class-I roads are highest standard roads with divided carriageway
(Expressway) with Average Daily Traffic (ADT) of 20,000 Passenger Car
Unit (PCU) or more in 20 years perspective period.
❖ Design speed of class-I roads in plain terrain is 120 kmph.

(2) Class-II (Arterial roads)

❖ Class-II roads are those with ADT of (5000-20,000) PCU in 20 years
perspective period.
❖ Design speed of class-II roads in plain terrain is 100 kmph
❖ Arterial roads is also known as path of road network (through traffic)

Er. Sabin Pokhrel

 Functional /Technical Classification…
29

(3) Class-III (Collector roads)

❖ Class-III roads are those with ADT of (2000-5000)
PCU in 20 years perspective period.
❖ Design speed of class-III roads in plain terrain is 80
kmph

(4) Class-IV (Local roads)

❖ Class-IV roads are those with ADT of less than 2000
PCU in 20 years perspective period.
❖ Design speed of class-IV roads in plain terrain is 60
kmph

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30

AADT (Annual Average Daily Traffic) = It is the

average traffic of 365 days.
ADT (Average Daily Traffic) = It is the average traffic
of 3 to 7 days.

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31

Q. Which of the following is most important roads?

(a) Class-I roads (>20,000 PCU)

(b) Class-II roads (5000-20000 PCU)

(c) Class-III roads (2000-5000 PCU)

(d) Class-IV roads (<2000 PCU)

Er. Sabin Pokhrel

32

Q. A portion of roads for fast moving vehicles is

known as:
(a) Expressway

(b) Motorway

(c) Both of above

(d) Carriageway

Er. Sabin Pokhrel

33

Q. A portion of roads for fast moving vehicles is

known as:
(a) Expressway

(b) Fast-track

(c) Both of above

(d) Carriageway

Er. Sabin Pokhrel

 Question
34

Exam Asked Questions:

Q. Highway Code denoted by BP Highway is
(a) NH01 (Mahendra Highway)

(b) NH03 (Mid-Hill Highway or Puspalal Marga)

(c) NH06 (Tamor Corridor)

(d) NH13

Er. Sabin Pokhrel

 Questions
35

Exam Asked Question

Q. A road within a town is called:
(a) Trunk road
(b) Carriage road
(c) Country Road
(d) Street
Q. A circumferential road, built around an urban area to enable free
flow of traffic is called:
(a) Ring Road
(b) Loop Road
(c) Mid strip
(d) Circular Road

Er. Sabin Pokhrel

 Co-relation Between Administrative
36
and Functional Classification
Plain and Rolling Mountainous and
Terrain Steep Terrain

National Highway I,II II, III

Feeder Roads II, III III, IV

Er. Sabin Pokhrel

 Terrain Classification (As per NRS-
37
2070 B.S.) (4 types)
SN Terrain % Cross Slope Degree of Curve
Type
1 Plain (0-10) % (0-5.7) degree

2 Rolling (10-25) % (5.7-14) degree

3 Mountainous (25-60) % (14-31) degree

4 Steep > 60 % > 31 degree

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38

As per NRRS-2071 B.S., there are two types of terrain

(a) Terai (Equivalence to Plain & Rolling terrain)

(b) Hill (Equivalence to Mountainous and Steep

Terrain)
❖ If the percentage cross slope of an area is less or
equal to 25 % then the terrain is known as terai
and if greater than 25 % is known as Hill

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39

Xm. Q If the percentage cross slope of the area is 15

%, then the terrain is:
(a) Plain

(b) Rolling

(c) Mountainous

(d) Steep

Er. Sabin Pokhrel

40

Xm. Q If the percentage cross slope of the area is 50

%, then the terrain is:
(a) Plain

(b) Rolling

(c) Mountainous

(d) Steep

Er. Sabin Pokhrel

 Question
41

Xm Q. Degree of road curve is defined as the angle

in degrees subtended at the centre by an arc of:
(a) 10 m

(b) 20 m

(c) 30 m

(d) 40 m

Er. Sabin Pokhrel

 Equivalency Factor:
42

PCU = Passenger Car Unit

PCE = Passenger Car Equivalent
➢ Both PCU and PCE are the equivalency factor.

Er. Sabin Pokhrel

 Vehicle type with their corresponding
43
Equivalency factor
SN Vehicle Type Equivalency
Factor (PCU )
1 Bicycle, Motorcycle, scooter, 0.5
Moped

2 Car, Auto-ricksaw, light van, 1.0

pickup van
3 Light (mini) truck, tractor without 1.5
trailor , Ricksaw
4 Truck, Bus, Minibus, Tractor with 3.0
trailor (tractor)
Er. Sabin Pokhrel
5 Non-motorized Carts (Bullock 6.0
 Questions
44

Xm. Q. Which vehicle has the highest Equivalent PCU?

(a) Car (1)
(b) Light Truck (1.5)
(c) Bus (3)
(d) Bullock Carts (6)

Q. Which vehicle has the lowest Equivalent PCU?

(a) Car (1)
(b) Light Truck (1.5)
(c) Bus (3)
(d) Bullock Carts (6)

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45

Xm According to NRS 2070, which of the following

have same PCU?
(A) Bicycle (0.5) and Rickshaw (1.5)
(B) Auto rickshaw (1) and Tractor (3)
(C) Tractor without Trailer (1.5) and Rickshaw (1.5)
(D) None of the above

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46

D Prasad Sir
Q. Which of the following vehicle has lowest PCU?
(a) Bicycle (0.5) (b) Scooter (0.5)
(c) Motorcycle (0.5) (d) All of above

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47

Q. If the number of motorcycle is 30, car is 20 and

bus is 10 then the PCU is:
(a) 10 PCU (c) 60 PCU
(b) 30 PCU (d) 65 PCU
Solution:
Motorcycle = 30*0.5 = 15 PCU
Car = 20*1 = 20 PCU
Bus = 10*3 = 30 PCU

Er. Sabin Pokhrel

 Design Speed (kmph)
48

Road Plain Rolling Mountainous Steep

Class
I 120 100 80 60

II 100 80 60 40

III 80 60 40 30

IV 60 40 30 20
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49

Q The design speed of Class-I road in steep terrain is:

(a) 40 kmph

(b) 60 kmph

(c) 80 kmph

(d) 120 kmph

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50

Xm Q The design speed of Class-I road in plain

terrain is:
(a) 40 kmph

(b) 60 kmph

(c) 80 kmph

(d) 120 kmph

Er. Sabin Pokhrel

 Questions
51

Exam Asked Questions:

Q. The design speed for hill terrain of trunk road is
(a) 20 kmph
(b) 30 kmph
(c) 40 kmph
(d) 50 kmph

Q. For transportation purpose in Nepal, the first preference is given to:

(a) Airlines
(b) Roadways
(c) Railways
(d) Waterways

Er. Sabin Pokhrel

 Road Survey
52

Q. What are the stages of road survey? (5 marks)

Answer:
The stages of road survey are:
(1) Map Study

(2) Reconnaissance Survey

(3) Preliminary Survey

(4) Detailed (Location) Survey

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53

(1) Map Study:

 The probable alignment can be located from the
following details available on map:-
- Alignment avoiding valleys, ponds or lakes
- When road has to pass a row of hills, possibility of
crossing through mountain passes.
- Approximate location of bridge site.
- When a road is to be connected between two stations,
one on the top & other on the foot of the hill, then
alternative route can be suggested keeping in view the
permissible gradient, say ruling gradient.

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54

(2) Reconnaissance Survey:

Some of the details to be collected during reconnaissance are:-
- Valley, ponds, marshy land, ridge, hills, permanent structures
& other obstructions along the route which are not available
in map.
- Maximum flood level & natural ground level.
- Soil type & geological features
- Sources of construction material

- When the area is vast or terrain is difficult reconnaissance

may be done by aerial survey.
As a result of the reconnaissance, a few alternative alignments
may be chosen for further study

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55

(3)Preliminary Survey
Objectives of preliminary survey are:
 To survey the various alternative alignment & collect
necessary physical information & details of topography,
drainage & soil.
 To compare the different proposals in view of the
requirements of a good alignment.
 To estimate quantity of earthworks & construction
aspects & workout the cost of alternatives proposals
 To finalized the best alignment from all considerations.

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56

(4) Detailed (Location) Survey

 It is also known as Final Survey

 The alignment that is finalized by preliminary survey is

located on the field by establishing centerline.
 Now the detail survey is carried out for collecting the
information necessary for the preparation of plan &
construction details for the highway project.
 The data are;

-Topographical detail
- -Soil profile

- -Drainage

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57

Xm The stages (steps or series) of road survey is:

(a) Map study-Preliminary survey-Reconnaissance

survey-Detailed Survey
(b) Map study- Detailed Survey - Preliminary survey-

Reconnaissance survey
(c) Detailed Survey - Map study-Preliminary survey-

Reconnaissance survey
(d) Map study- Reconnaissance survey- Preliminary
survey- Detailed Survey
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58

Q. The first stage of road survey is:

(a) Reconnaissance Survey
(b) Preliminary Survey
(c) Detailed (Location) Survey
(d) All of the above

Er. Sabin Pokhrel

 Highway Alignment (Alignment)
59

Q. Define Alignment. What are the basic Requirements of

Road Alignment ? (5 marks)
Answer: The position or layout of centre line of the road
on the ground is called alignment.
The basic requirement of road alignment are:
(I) Short
(II) Easy
(III) Safe
(IV) Comfort

(V) Economical
(VI) Useful

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 Highway Alignment (Alignment)
60

(1) Short
❖ Perpendicular distance between any two points is the
shortest distance.
❖ Shortest distance reduces the cost of construction,
construction time, vehicle operation cost and road
maintenance cost.
❖ The probability of accident also reduces in short
roads.
(2) Easy:
❖ The road should be easy for construction, vehicle
operation and road maintenance.

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61

(3) Safe:
❖ The road should be safe for construction, vehicle

operation and road maintenance.

❖ There should be minimum casaulties or fatalities

during construction, vehicle operation and road

maintenance.
(4) Comfort:
❖ The road should be comfort for vehicle driving and
travelling passengers.
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62

(5) Economical:
❖ As far as possible and as best as practicable,

minimum cost should be used for construction,

vehicle operation and road maintenance
(6) Useful:
❖ The road should be benefitted directly or

indirectly for many of the users.

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63

Q. Which of the following criteria is given first

priority?
(a) Short

(b) Easy

(c) Safe

(d) Comfort

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64

Q. Which of the following criteria is given first

priority?
(a) Short

(b) Easy

(c) Safe

(d) All of the above

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65

Q. Which of the following criteria is given priority

during the alignment of the road ?
(a) Short

(b) Easy

(c) Safe

(d) All of the above

Er. Sabin Pokhrel

 :
66

Q. What are the various factors controlling Highway Alignment? (10)

Answer:
The various factors controlling highway alignment are:
(I) Obligatory Points
(II) Geometric Design
(III) Traffic
(IV) Economy
(V) Political Considerations
(I) Obligatory Points
(A) Positive Obligatory Points:
❖ Points through which the road alignment is to pass:
 An industrial area or mine zone to which a highway is to serve additionally

Tourists spot, bridge site ( suitable), tourist spot , hill pass, Link with intermediate
town, health post, Rural Municipality(RM), District Co-ordination Committee (DCC),
School areas, College areas

Er. Sabin Pokhrel

 Points through which the road alignment is to pass…
67

(i) Alignment along a hill side pass

Er. Sabin Pokhrel

 Points through which the road alignment is to pass…
68

(2) Alignment to suit the proper location of bridge

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 Points through which the road alignment is to pass…
69

(3) Alignment to connect intermediate town:

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 Points through which the road alignment is to pass…
70

(4) Alignment avoiding intermediate area

(5) Alignment connecting industrial area

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71

(B) Negative Obligatory Points:

❖ Points through which the road alignment should not
pass:
(1) Marshy land, water logged areas, etc

(2) Historically and Archeologically important property

(3) Restricted zone for defence, national security

(4) Costly structural element requiring heavy

compensation
(5) Densely populated areas

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72

(II) Geometric Design:

➢ The different types of geometric design parameters

like camber, Super-elevation, Sight distance,

transition curve, vertical curve, etc affects the road
alignment.
(III) Traffic:
➢ Road should be benefitted to the maximum number
of pedestrian and vehicular traffic.

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73

(IV) Economy:
➢ Appropriate amount of budget should be allocated

for road survey, road design, road construction, etc.

(V) Political Considerations:
➢ The instability of political parties affects the
planning, construction and maintenance of roads.

Er. Sabin Pokhrel

 Question
74

Exam Asked Questions:

Q. Obligatory points in a road alignment are points
through which:
(a) The road alignment is to pass

(b) The road alignment should not pass

(c) Both of above

(d) None of the above

Er. Sabin Pokhrel

 Geometric Design
75

Q What are the basic design control and criteria for

highway design? (5 marks)
Answer: The basic design control and criteria for highway
design are:
(1) Design Speed

(2) Design Vehicle

(3) Topography

(4) Traffic Factors

(5) Design Hourly volume and capacity

(6) Environmental and other factors

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76

(1)Speed:
➢ Speed affects the width of the road, radius of
curve,etc
Analysis of spot speed
➢ Spot speed is measure by an Instrument named as
Enoscope.

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77

(I) 98th Percentile Speed

❖ The 98 % of vehicle move below this speed.
❖ It is taken as design speed.
(II) 85th Percentile Speed:
❖ The 85 % of vehicle moves below this speed.
❖ It is taken as upper speed limit.
(III) 15th Percentile speed:
❖ It is used to determine minimum speed limit as major
highways.
(IV) 50th Percentile speed (Median Speed)
❖ It is the speed at which there are as many vehicles going
Er. Sabin Pokhrel
faster as there are going slower
78

(2) Design Vehicle:

❖ The geometric elements of road naturally depend

on the design vehicle, its characteristics, size, &

shape using the road.
❖ It is therefore, essential to examine various types
of vehicles in use in the country

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79

Design length of vehicle = 18 m (It affects the radius

of the curve)
Design width of vehicle = 2.5 m (It affects the width
of the road)
Design height of vehicle = 4.75 m (It affects the
vertical clearance height)
Design Single Axle load = 100 kN (It affects the
pavement strength)
Note: Average speed of pedestrian = 1.2 m/sec
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80

(3) Topography:
❖ Topography in general influences the physical location
of highway.
❖ The design elements of a highway in hilly region are
affected to a considerable degree by the physical
features such as hills, valleys, steepness of slope, stream
crossings etc.
(4) Traffic volume & composition: -
 Traffic volume is the number of vehicle crossing a section
of road per unit time at any selected period.

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 Geometric Design…
81

Traffic volume:
❖ Traffic volume is the number of vehicles crossing a section of
road per unit time at any selected period.
Traffic capacity:
❖ It is the number of vehicles passing per lane in an hour

❖ Maximum or basic capacity is determined by:

C = (1000*V)/S
Where,
C = Capacity of vehicles per hour per lane
V = Speed in km-ph
S = Average centre to centre spacing of vehicles in meter

Er. Sabin Pokhrel

 Question
82

Q. If the average centre to centre spacing of a vehicles is 25 meters,

then basic capacity of a traffic lane at a speed of 50 kmph is:
(a) 1000 Veh/hr/lane (b) 2000 Veh/hr/lane
(c) 3000 Veh/hr/lane (d) 4000 Veh/hr/lane
Hints:
Spacing (S)= 25 meters
Speed (V) = 50 kmph
Then,
C = (1000*V)/S
= (1000*50)/25
= 2000 Vehicles/hour/lane

Er. Sabin Pokhrel

83

Traffic Density:
The number of vehicles in one kilometer of road
distance is known as traffic density. i.e. veh/km.

Xm. Which of the following affects the traffic density?

(a) Length of vehicle

(b) Width of vehicle

(c) Height of vehicle

(d) All of above

Er. Sabin Pokhrel

 Cross sectional elements of
84
rural/Urban roads:
Q. Draw a neat sketch of cross section of road. (2 marks)

Er. Sabin Pokhrel

85

Xm Q Which of the following is not related with the

cross-section of the road?
(a) Camber

(b) Width

(c) Thickness

(d) Tailrace (It is related with hydropower)

Er. Sabin Pokhrel

86

Xm Q Which of the following is not related with the

cross-section of the road?
(a) Camber

(b) Width

(c) Thickness

(d) Gradient

Er. Sabin Pokhrel

87

There are two types of gradient:

(I) Longitudinal gradient (Gradient)
It is the gradient which is along the length of the road.
(II) Transverse Gradient (Camber )
It is the gradient which is across the width of the
road.

Er. Sabin Pokhrel

88

Q . Define Right of Way (ROW)

▪ It is the total area of land acquired for the road
along its alignment.
▪ It depends on the importance of the road and
possible future development.
▪ It is desirable to acquire more width of land as the
cost of adjoining land invariably increases very
much , soon after the new highway is constructed.
Er. Sabin Pokhrel
 Right of Way (ROW)
89

SN Type of Road Total Right of Way

1 Highway (National Highway) 50 m
2 Feeder Roads 30 m
3 District Roads 20 m
4 City Roads
(a) 4 lanes 50 m
(b) 2 lanes 30 m
Er. Sabin Pokhrel
90

Exam
Q. As per NRS-2070, the ROW of Highways in
Nepal is:
(a) 20 m (c) 30 m
(b) 25 m (d) 50 m
Q. The full width of land acquired before finalizing a
highway is known as
(a) Width of formation (c) Shoulder
(b) Carriageway (d) Right of Way

Er. Sabin Pokhrel

91

Q. As per NRS-2070, the ROW of Highways in

Nepal from centre line of the road is:
(a) 20 m (c) 30 m
(b) 25 m (d) 50 m
Note:
As per NRRS, the ROW for Village roads, Agricultural
roads = 15 meter.

Er. Sabin Pokhrel

Carriageway or width of pavement:
▪ Carriageway may be defined as that strip of road which is constructed
for the movement of vehicular traffic.
▪ It may be cement concrete road or bituminous pavement.
▪ Width of carriageway is determined on the basis of the width of the
vehicle and the minimum side clearance for safety.
▪ Carriage width (CW) = Width of lane (Tw) * No. of lane (n)
▪ Width of carriageway as per NRS-2070
 Questions
94

Q. The portion of road surface, which is used by vehicular

traffic is known as:
(a) Shoulder
(b) Carriageway
(c) Expressway
(d) All of Above
Q. Exam. The width of 4 lane road is: (Width = 4*3.5 = 14 m)
(a) 3.5 m
(b) 3.75 m
(c) 7m
(d) 14 m

Er. Sabin Pokhrel

95

Sub-way:
An underground passage for the movement of
pedestrain traffic and vehicular traffic is known as
Subway.
Fly-over:
An overground passage for the movement of
pedestrain traffic and vehicular traffic is known as
flyover.

Er. Sabin Pokhrel

Shoulder:
▪ It is provided along the road edge to serve as an emergency
lane for vehicle.
▪ It act as a service lane for vehicles that have broken down.

▪ It should have sufficient load bearing capacity even in wet weather.

▪ The surface of the should be rougher than the traffic lanes so that
vehicles are discouraged to use the shoulder as a regular traffic.

▪ The colour should be different from that of the pavement

to be distinct.

▪ The width of shoulders on either side of the carriageway

shall be at least 0.75m.
99

Xm The minimum width of shoulder is:

(a) 0.75 m (c) 2 m
(b) 1.5 m (d) 3.75 m

Xm The minimum width of shoulder on each side

(either side) is:
(a) 0.75 m (c) 2 m
(b) 1.5 m (d) 3.75 m

Er. Sabin Pokhrel

100

The minimum width of shoulder on both sides of the

road is:
(a) 0.75 m (c) 2 m
(b) 1.5 m (d) 3.75 m
Q. The minimum width of shoulder for road class-III as
per NRS is?
(a) 0.75 m (c) 1 m
(b) 1.5 m (d) 2 m

Er. Sabin Pokhrel

101

Q. The minimum width of shoulder for road class-III on

each side of the road as per NRS is?
(a) 0.75 m (c) 1 m
(b) 1.5 m (d) 2 m

Er. Sabin Pokhrel

 Footpath
102

➢ A portion of the traffic way that is used by

pedestrains only is called footpath.
❖ Minimum width of footpath required is 1.5 meter
Hourly design flow (Both-ways) of 15 Footpath Width (m) (Each Side)
minute peak period

Up-to 500 1.5 meter

500 – 1500 2.0 meter

1500 – 2500 2.5 meter

2500 - 3500 Er. Sabin Pokhrel 3.0 meter

103
Footpath…
Exam
Q. A portion of the traffic way that is used by pedestrains
only is called
(a) Footpath (c) Footway
(b) Sidewalk (d) All of above

Xm The minimum width of footpath as per NRS 2070 is?

(a) 1.5 m (b) 2 m
(c) 2.5 m (d) 3 m
Er. Sabin Pokhrel
104

The minimum width of footpath on each side as per

NRS 2070 is?
(a) 1.5 m (b) 0.75 m
(c) 2.5 m (d) 3 m

The minimum width of footpath on both side as per

NRS 2070 is?
(a) 1.5 m (b) 2 m
(c) 2.5 m (d) 3 m

Er. Sabin Pokhrel

105

Q( India Bix)
If the number of pedestrian in 15 minutes is 300, then
the minimum width of footpath required is:
(a) 1.5 m

(b) 2 m

(c) 2.5 m

(d) 3 m

Er. Sabin Pokhrel

106

Solution:
Number of pedestrian in 15 minutes = 300
Number of pedestrian in 1 minutes = (300/15)
Number of pedestrian in 60 minutes = (300/15)*60
= 1200.

Er. Sabin Pokhrel

107

If the number of pedestrian in 60 minutes is 300, then

the minimum width of footpath required is:
(a) 1.5 m

(b) 2 m

(c) 2.5 m

(d) 3 m

Er. Sabin Pokhrel

108

Bicycle track:
➢ The portion of road that is used by pedal bicyclists

is known as bicycle track.

➢ The minimum width of bicycle track is 1.2 m (Each

side)
➢ As per NRS, bicycle track is adopted if the number

of bicycle exceeds 1000 per day.

Er. Sabin Pokhrel

 Gradient
109

Q. Define gradient and what are the types of gradient?

(1+4)
❖ Gradient is rate of rise or fall along the length of road
with respect to horizontal.
❖ It is expressed as ratio of 1 in x

Types of Gradient:
(1) Ruling Gradient

(2) Limiting Gradient

(3) Exceptional Gradient

(4) Minimum Gradient

Er. Sabin Pokhrel

110

Ruling Gradient:
➢ The gradient attempted by designer is known as ruling
gradient.
➢ Ruling gradient is also known as design gradient or
maximum gradient.
Limiting Gradient:
➢ The gradient steeper than ruling gradient is known as
limiting gradient.
Exceptional Gradient:
➢ The gradient in exceptional case i.e. above than maximum
or below than minimum is known as exceptional gradient.
Er. Sabin Pokhrel
111
Gradient…
❖ The maximum length of an exceptional gradient
should not exceed 60 meter in one kilometer road
length
❖ The stretches of exceptional gradient should be
separated by a minimum length of 100 meter with
limiting or flatter gradient.
Design Speed 20 30 40 60 80 100 120
(Kmph)

Maximum 12 10 9 7 6 5 4
Gradient (%)

Er. Sabin Pokhrel

112

Minimum Gradient:
The gradient provided at least to drain off the rainfall is
known as minimum gradient
➢ The minimum longitudinal gradient for road is 1 %

➢ The minimum longitudinal gradient for drain is 0.5 %

Q. As per NRS-2070 B.S. the maximum gradient for road is:

(a) 4% (b) 7% (c) 10 % (d) 12 %
(b) 5% (b) 8% (c) 12 % (d) 15 %
(c) 5% (b) 6% (c) 7 % (d) 8 %
(d) 5% (b) 6% (c) 7 % (d) None
(e) 4% (b) 5% (c) 6 % (d) All of above

Er. Sabin Pokhrel

113

Q. As per NRRS-2071 B.S. the maximum gradient for

Hair Pin Bend is:
(a) 4% (b) 7% (c) 10 % (d) 12 %

Er. Sabin Pokhrel

 Super-elevation (e)
114

❖ Raising of outer edge with respect to inner edge is

known as super-elevation.

❖ In equilibrium super-elevation, f = 0. So,

Er. Sabin Pokhrel

115
Super-elevation…
❖ For mixed traffic condition, speed is designed for 75 %
speed is re

❖ Maximum super-elevation to be provided is limited to:

✓ In plain,rolling, mountainous and steep terrain = 7 %
✓ In snow bound areas = 7 %
✓ In hilly areas not bound by snows (Hair Pin Bend) = 10 %
❖ Minimum value of super-elevation should be equal to the
rate of camber of the pavement (Gradient on either side)

Er. Sabin Pokhrel

116
Super-elevation…
❖ The main function of providing super-elevation is to
counteract the Centrifugal force.
Exam:
Q. Raising of outer edge wrt inner edge is known as:
(a) Super-elevation (c) Banking
(b) Cant (d) All of above

Er. Sabin Pokhrel

117

Q. The maximum amount of super-elevation is:

(a) 4% (b) 5% (c) 6% (d) 7%
(b) 5% (b) 6% (c) 7% (d) 10%
(c) 4% (b) 5% (c) 6% (d) None
(d) 4% (b) 5% (c) 6% (d) All of above

Er. Sabin Pokhrel

118

Q. The maximum amount of super-elevation for hill

road is:
(a) 5% (b) 6% (c) 7% (d) 10%
(b) 4% (b) 5% (c) 7% (d) None

Q. The minimum amount of Super-elevation is:

(a) 4% (b) 7% (c) 10% (d) Camber
(a) 0% (b) 7% (c) 10%
(d) Gradient on either side of road

Er. Sabin Pokhrel

Q1. The radius of a horizontal circular curve is 100 m. The design is speed of 50
Kmph and the design coefficient of lateral friction is 0.15
a) Calculate the superelevation required if full lateral friction is assumed to develop.
b) calculate the coefficient of friction needed if no superelevation is provided.
c) calculate the equilibrium superelevation if the pressure on inner and outer wheels
should be equal.
Given,
Radius (R) = 100 m
Speed (V) = 50 Kmph
Coefficient of lateral friction (f) = 0.15
We have,
Super-elevation is given by equation

𝑽𝟐
e+f= ……………………… (i)
𝟏𝟐𝟕𝑹
 𝑽𝟐
e+f= …………… (i)
𝟏𝟐𝟕𝑹
a) If e = ? f = 0.15
c) f =0 e = ?
502
e + 0.15 = = 0.917
127∗100 𝑉2
e = 0.917-0.15 e+f=
127𝑅
e = 0.047 50
e=
127

b) If e = 0 f = ? e = 0.19

𝑉2
e+f=
127𝑅

502
0+f=
127∗100
f = 0.19
121

(a) Since value of super-elevation is less than 0.07. so

OK.
Hence super-elevation = 0.047
(b) Since the value of f is greater than 0.15. so NOT
OK.
Hence, coefficient of lateral friction = 0.15
(c) Since value of super-elevation is greater than
0.07. so NOT OK.
Hence super-elevation = 0.07

Er. Sabin Pokhrel

 Camber:
122

➢ Convexity provided on the cross section of the road is called

camber.
➢ The main function of camber is to drain off the rainwater.

➢ Camber is designated by1 in n which means 1 vertical to n

horizontal.
➢ Camber is also represented by X % which means X in 100.

Types Of Camber:
(1) Straight Line Camber
(2) Parabolic Camber
(3) Composite Camber

Er. Sabin Pokhrel

123

Er. Sabin Pokhrel

124

➢ Straight Line Camber is adopted for the very flat slope

with cement concrete pavement.
➢ Parabolic camber is designed for fast moving vehicle
and generally with bituminous road.
➢ Composite cambers are used for the slow moving
vehicles.
➢ The highest point of the road (Camber) is known as
crown.
➢ For straight line camber (Y) = n*X
➢ For parabolic camber (Y) = (2n/W)*X²

Er. Sabin Pokhrel

Types Camber:
 Camber in %
126

Datas to Remember:
Types of Surface Amount of Camber(%)
1) Earthern Road 5%
2) Gravel/WBM road/ 4%
Surface treatment
3) Bituminous Road 2.5 %
4) Cement Concrete (1.5-2)%

Er. Sabin Pokhrel

127

WBM = Water Bound Macadam

➢ There are two types of WBM road i.e. Dry Bound

Macadam and Wet Bound Macadam road.

Er. Sabin Pokhrel

128

Xm Q The binding materials used in WBM road is:

(a) Clay (c) stone-dust
(b) Cement (d) Bitumen
Xm Q The binding materials used in road is:
(a) Clay (c) stone-dust
(b) Cement (d) all of above

Er. Sabin Pokhrel

129

Q The binding materials used in WBM road is:

(a) Clay (c) stone-dust
(b) Cement (d) All of above
Xm Q The binding materials used in bituminous road
is:
(a) Clay (c) stone-dust
(b) Cement (d) Bitumen

Er. Sabin Pokhrel

130

Xm Q The binding materials used in Cement concrete

road is:
(a) Clay (c) stone-dust
(b) Cement (d) Bitumen

Er. Sabin Pokhrel

131

Xm Q Which of the following is type of camber?

(a) Straight line camber

(b) Parabolic camber

(c) Straight at edge and parabolic at crown

(d) All of the above

Er. Sabin Pokhrel

132

Xm(2080) Q Which of the following is not type of

camber?
(a) Straight line camber

(b) Parabolic camber

(c) Composite Camber

(d) Circular Camber

Er. Sabin Pokhrel

133

Q Which of the following is best type of camber?

(a) Straight line camber

(b) Parabolic camber

(c) Composite Camber

(d) All of the above

Er. Sabin Pokhrel

134

Q Which of the following is maximum types of

camber used in National highway of Nepal?
(a) Straight line camber

(b) Parabolic camber

(c) Composite Camber

(d) All of the above

Er. Sabin Pokhrel

135

Q Which of the following is maximum types of

camber used in roads of Nepal?
(a) Straight line camber

(b) Parabolic camber

(c) Composite Camber

(d) All of the above

Er. Sabin Pokhrel

136

➢ The total length of National Highway of Nepal =

14913 km
➢ AWR = All Weather Roads
➢ In AWR, vehicles can run in 12 months of the year
➢ Eg: Bituminous roads and cement concrete roads
➢ FWR = Fair Weather Roads.
➢ Eg: Earthen road and Gravel roads.
➢ In FWR, vehicles can run in some of the seasons only.
➢ Maximum road length of Nepal is Fair Weather
Roads(FWR) i.e
Er. Sabin Pokhrel
137

Xm Q In a region of scanty rainfall the camber

provided is?
(a) Nil

(b) Steeper

(c) Flatter

(d) All of the above

Er. Sabin Pokhrel

138

Q In a region of heavy rainfall the camber provided

is?
(a) Nil

(b) Steeper

(c) Flatter

(d) All of the above

Er. Sabin Pokhrel

139

Q In a region of no rainfall the camber provided is?

(a) Nil

(b) Steeper

(c) Flatter

(d) All of the above

Er. Sabin Pokhrel

 Numericals:
140

Q.1 For bituminous road of four lanes, a 3 % slope

for camber is provided. What should be the height
of crown if provided with :
(a) Straight line camber

(b) Parabolic Camber

Solution:
Here, Width of road (W)= 4*3.5 = 14 meter
Camber (n) = 3 % = 0.03
Height of crown (Y) = ?

Er. Sabin Pokhrel

141

(a) For Straight line camber

Height of crown (y)= n*x
= 0.03* (14/2)
= 0.21 meter or 21 cm.
(b) For parabolic camber

Er. Sabin Pokhrel

 Sight-Distance
142

❖ The distance along the length of the road is known

as sight distance.
❖ There are three types of sight distance:
(1) Stopping Sight Distance (SSD)
(2) Overtaking Sight Distance (OSD)
(3) Intermediate Sight Distance (ISD)
(I) Stopping Sight Distance (SSD)
➢ The safe distance required to stop the vehicles is
known as Stopping Sight distance.

Er. Sabin Pokhrel

 Sight-Distance
143

(I) Stopping Sight Distance (SSD):

Er. Sabin Pokhrel

 Criteria for measurement
144

▪ Height of driver’s eye above road

surface (H)
▪ Height of object above road surface
(h)

H
h
IRC/ NRS-
2070
H = 1.2 m
h = 0.15 m

Er. Sabin Pokhrel

145

V = speed (kmph)
t= reaction time of the driver (2.5 sec)
f= coefficient of longitudinal friction (0.35-0.42)
n= gradient (If not given, take n= 0%)
n= +ve for ascending gradient
n= -ve for descending gradient
Eta(n) = Brake efficiency (If not given, take it as
100% i.e. 1)

Er. Sabin Pokhrel

 For single lane one way traffic road or multilane two-way traffic
SSD = SD
146
A. Single lane road two-way traffic

SSD = 2 * SD

Er. Sabin Pokhrel

 PIEV Theory
147

PIEV stands for

P = Perception
I = Intellection
E= Emotion
V= Voliation

Er. Sabin Pokhrel

148

Exam
Q. The reaction time of the driver during normal condition is
(a) 2 sec (c) 3 sec
(b) 2.5 sec (d) 3.5 sec
Q. The reaction time of the driver during overtaking (Complex
condition) is
(a) 2 sec (c) 3 sec
(b) 2.5 sec (d) 3.5 sec
Q. The reaction time of the driver is
(a) (1.5-2) sec (c) (2.5-3) sec
(b) (2-2.5) sec (d) (3-3.5) sec

Er. Sabin Pokhrel

149

Xm The reaction time of the driver is:

(a) 1 sec (b) 2 sec
(c) 3 sec (d) 4 sec

Er. Sabin Pokhrel

Sight Distance [Numerical-1]
A two-lane road is used for two-way traffic for design speed of 80
kmph. If the coefficient of friction between the road surface and the
tyres is 0.37 and reaction time of driver is 2.5 sec. Calculate the safe
stopping sight distance.

Given:
V= 80 kmph f= 0.37 t= 2.5 Sec.

We have,
𝒗𝟐
SD = 𝟎 ⋅ 𝟐𝟕𝟖𝒗 ∗ 𝒕 +
𝟐𝟓𝟒𝒇
802
𝑆𝐷 = 0 ⋅ 278 ∗ 80 ∗ 2 ⋅ 5 +
254 ∗ 0 ⋅ 37
SD = 55.6 + 68.1
SD = 123.7 m

For Two-lane Two-way road, SD= SSD

SSD = 123.7 m
Sight Distance [Numerical-2]
In a single lane road, two cars are approaching from the opposite directions at
a speed of 60 kmph and 80 kmph. If the coefficient of friction between the
road surface and the tyre is 0.35, then calculate the minimum sight distance
required to avoid a head-on-collision of two cars.
Ans: 209.8 m

For Car-1 For Car-2

V1 = 60 kmph f= 0.35 assume V2 = 80 kmph f= 0.35 assume
t= 2.5 Sec. 𝒗𝟏𝟐 t= 2.5 Sec. 𝒗𝟐𝟐
SD1 = 𝟎 ⋅ 𝟐𝟕𝟖𝒗𝟏 ∗ 𝒕 + SD2 = 𝟎 ⋅ 𝟐𝟕𝟖𝒗𝟐 ∗ 𝒕 +
𝟐𝟓𝟒𝒇 𝟐𝟓𝟒
602
𝑆𝐷1 = 0.278 ∗ 60 ∗ 2 ⋅ 5 + 𝑆𝐷2 = 0.278 ∗ 80 ∗ 2 ⋅ 5
254 ∗ 0.35
SD1 = 82.2 m SD2 = 127.6 m

For Single-lane Two-way road, SSD =

SD1 + SD2
82.2 + 127.6 = 209.8 meter
152

Skidding:
✓ If the distance travelled by the vehicle is more than the
circumferential movement of the wheel due to rotation,
it results is skidding.
✓ Skidding occurs due to more friction on the road.

Slipping:
✓ If the distance travelled by the vehicle is less than the
circumferential movement of the wheel due to rotation,
it results is slipping
✓ On wet surface, slipping occurs.

Er. Sabin Pokhrel

 Overtaking Sight Distance (OSD)
153

Q. Define Overtaking Sight Distance (OSD). Write an

expression for the design length of OSD. (1+4)
Answer:
❖ The safe distance required to overtake the slow

moving vehicle by the fast moving vehicle is known

as Overtaking Sight Distance.

Er. Sabin Pokhrel

 Overtaking Sight Distance (OSD)
154

Er. Sabin Pokhrel

155

➢ Vehicle A is the overtaking vehicle and A1,A2, A3

are its various positions
➢ Vehicle B is the overtaken vehicle and B1,B2 are its
various positions
➢ Vehicle C is the vehicle coming from opposite
direction and C1,C2 are its various positions.

Er. Sabin Pokhrel

156

Er. Sabin Pokhrel

157

Safe OSD for two way traffic = d1+d2+d3

Safe OSD for one way traffic = d1+d2

Er. Sabin Pokhrel

158

If speed of overtaken vehicle (Vb) is not given, then

take Vb= (V-x) kmph
The value of x ranges from (16 to 30) kmph,
generally x is taken as 16 kmph.

Er. Sabin Pokhrel

159

Q. If the speed of overtaken vehicle is 60 kmph, then

the required speed of overtaking vehicle is:
(a) 44 kmph (c) 76 kmph
(b) 60 kmph (d) 100 kmph

Er. Sabin Pokhrel

160

Solution:
Vb = (V-16)
V = Vb+16
V = 60 +16
V = 76 kmph

Er. Sabin Pokhrel

162

❖ Minimum length of overtaking zone = 3*OSD

❖ Desirable length of overtaking zone = 5*OSD

(III) Intermediate Sight Distance (ISD):

❖ It is defined as the twice the normal safe stopping

distance.
❖ It is also known as Headlight sight distance.

❖ ISD = 2*SD

Er. Sabin Pokhrel

Q.1 The speed of overtaking and overtaken vehicles are 80 kmph
and 60 kmph respectively, on a two-way traffic road. If the
acceleration of the overtaking vehicle is 0.9 m/sec2, Calculate the
safe overtaking sight distance.
Given,
Speed of Overtaking Vehicle (V) = 80 Kmph
Speed of Overtaken Vehicle (Vb)= 60 Kmph
Acceleration of overtaking vehicle (a) = 0.9 m/s2
OSD = ?
Road condition = Two-way traffic road
We have,
OSD = d1 + d2 + d3
OSD = 0.278 Vb*t + 0.278 Vb*T + 2S + 0.278 V * T

a = 0.9 m/s2, 3600

𝐴 =0⋅9∗ = 3.24 𝑘𝑚𝑝ℎ per second
1000
Assume (t) = 2 sec.
S = 0.2vb + 6 = 0.2*60+6 = 18m

14.4 𝑆 14.4 ∗18

T= = = 8.94 𝑠𝑒𝑐.
𝐴 3.24

OSD = 0.278 Vb*t + 0.278 Vb*T + 2S + 0.278 V * T

= (0.278*60*2) + (0.278*60*8.94 + 2*18) + (0.278*80*8.94)

= 33.4 + 185.1 + 198.8

OSD = 417. 3 m
165

Q(1) Also calculate the minimum length and desirable

length of overtaking zone.
Solution:
Minimum length of overtaking zone = 3*OSD
= 3*417.3
= 1251.9 m
Desirable length of overtaking zone = 5*OSD
= 5*417.3
= 2086.5 m

Er. Sabin Pokhrel

 Grade Compensation
166

Q. Define Grade Compensation . (2 marks)

❖ Reduction in gradient is known as grade
compensation.
❖ Grade Compensation (in %) = (30+R)/R %

❖ Grade compensation is subjected to a maximum

value of 75/R %
❖ As per IRC, grade compensation is not necessary for

gradient flatter than 4 %.

Er. Sabin Pokhrel

167

Q. The maximum grade compensation for a curve of

radius 75 m is?
(a) 1

(b) 0.1

(c) 0.01

(d) 0.016

Er. Sabin Pokhrel

168

Er. Sabin Pokhrel

169

Q. The maximum grade compensation for a curve of

radius 75 m is?
(a) 1 %

(b) 0.1 %

(c) 0.01 %

(d) 0.016 %

Er. Sabin Pokhrel

 Numericals
170

Q. While aligning a hill road with a ruling gradient of 6

%,a horizontal curve of radius 60 m is encountered.
Find the grade compensation and compensated
gradient at the curve.
Solution:
Here, Ruling gradient = 6 %
Radius (R) = 60 m
Then, Grade compensation (%) = (30+R)/R %
= (30+60)/60 %
= 1.5 %

Er. Sabin Pokhrel

171

Similarly, maximum limit of grade compensation

= 75/R %
= 75/60 %
= 1.25 %
Hence, provide a grade compensation of 1.25 %.
Now, Compensated Gradient
= Ruling Gradient – Grade Compensation
= 6 % - 1.25 %
= 4.75 % Ans.

Er. Sabin Pokhrel

Transition Curve
173

Xm Q. The radius of transition curve at the junction of

circular curve is:
(a) 0 (b) R (c) 2R (d) ∞

Q. The radius of transition curve at the junction of

straight line is:
(a) 0 (b) R (c) 2R (d) ∞

Er. Sabin Pokhrel

174

Xm (Biratnagar) The radius of curvature provided

along a transition curve is:
(a) Minimum at the beginning

(b) Same throughout its length

(c) Equal to the radius of circular curve

(d) Varying from infinity to the radius of circular curve

Er. Sabin Pokhrel

 Types of Transition Curve:
175

Er. Sabin Pokhrel

176

➢ Ideal transition curve is Clothoid

➢ Ideal transition curve for hill road is spiral.

Er. Sabin Pokhrel

177

Xm. Q Ideal transition curve is :

(a) Spiral (c) Cubic parabola
(b) Lemniscate (d) Clothoid
Xm. Q Ideal transition curve for hill road is :
(a) Spiral (c) Cubic parabola
(b) Lemniscate (d) Clothoid
Xm. Q The types of transition curve is :
(a) Spiral (c) Cubic parabola
(b) Lemniscate (d) All of above
Er. Sabin Pokhrel
Q. Define Transition Curve. Write an expression for the
design length of transition curve. (1+4)
➢ The curve in transit i.e. the curve between the straight
line and the circular curve is known as transition curve.
Design Length of Transition Curve:
The length of the transition curve should be determined as
the Maximum of the following three criteria:

1) Rate of change of centrifugal acceleration

2) Rate of introduction of designed super-elevation

3) Minimum length by IRC empirical formula

179

Er. Sabin Pokhrel

180

Er. Sabin Pokhrel

181

e = Super-elevation (%)
N = Rate of introduction of super-elevation
W = Width of the road (meter)
We= Extra-widening (meter)
V = Design Speed (kmph)
R = Radius of curve (meter)

Er. Sabin Pokhrel

182

Er. Sabin Pokhrel

Q1. Calculate the length of transition curve and shift using following
data:
Design speed (V) = 65 Kmph, Radius of the curve (R) = 220 m
Allowable rate of superelevation (rotated about CL) = 1 in 150 (1 in N
Pavement width including extra widening (B)= 7.5 m
a) Length of Transition Curve (By Rate of change of centrifugal acceleration)
𝟎.𝟎𝟐𝟏𝟓 𝑽𝟑
𝑳𝑺 = ……………………….(i)
𝑪𝑹
𝟖𝟎 𝟖𝟎
𝑪= = = 𝟎. 𝟓𝟕 m/s3
(𝟕𝟓+𝑽) (𝟕𝟓+𝟔𝟓)
𝟎.𝟎𝟐𝟏𝟓 𝑽𝟑 𝟎.𝟎𝟐𝟏𝟓 ∗𝟔𝟓𝟑
𝑳𝑺 = = = 47.1 m
𝑪𝑹 𝟎.𝟓𝟕∗𝟐𝟐𝟎
b) Length of Transition Curve ( By Rate of introduction of super-elevation)
Allowable rate of introduction of superelevation (1 in N) = 1 in 150
𝑽𝟐 𝟔𝟓𝟐
Superelevation rate ( ⅇ) = = = 𝟎. 𝟎𝟖𝟓[ ecalc.> emax, Provide max. limit v
𝟐𝟐𝟓 𝑹 𝟐𝟐𝟓 ∗𝟐𝟐𝟎

Check for safety against friction,

𝑽𝟐 𝟔𝟓𝟐
f= −ⅇ= − 𝟎. 𝟎𝟕 = 0.08 [ fcalc.< fmax, safe at
𝟏𝟐𝟕 𝑹 𝟏𝟐𝟕 ∗𝟐𝟐𝟎
Length of transition curve (rotated about center line)
ⅇ𝑵
𝑳𝑺 = 𝑾 + 𝑾ⅇ [B = W + We = 7.5 m
𝟐

𝟎.𝟎𝟕∗𝟏𝟓𝟎
𝑳𝑺 = 𝟕. 𝟓 = 39.37 m
𝟐

C) Length of transition curve (By Empirical Formula)

𝟐. 𝟕 𝑽𝟐 𝟐. 𝟕 ∗ 𝟔𝟓𝟐
𝑳𝑺 = = = 𝟓𝟏. 𝟖𝟓 𝒎
𝑹 𝟐𝟐𝟎

Adopt the highest value calculated from above three formula,

Therefore, Length of transition Curve (LS) = 51.85 m say 52 m

𝑳𝑺 𝟐 𝟓𝟐𝟐
Shift (S) = = = 𝟎. 𝟓𝟏 𝒎
𝟐𝟒 𝑹 𝟐𝟒 ∗ 𝟐𝟐𝟎
 Extrawidening
186

Q. Define Extra-widening (2 marks)

➢ The additional width provided on the roadway is known
as extra-widening.
➢ Total Widening = Mechanical Widening (Wm)+

Psychological Widening (Wps)

n = number of lanes, R = Radius of curve in meter

l = wheel base of vehicles (m) , V = design speed (kmph)

Er. Sabin Pokhrel

187

❖ Mechanical Widening is provided on inner side of the

curve.
❖ Psychological widening is provided on outer side of the
curve.
❖ Extra-widening is not provided if the radius of curve is
more than 300 meter.
❖ In hill road (Sharp turn) , extrawidening is provided in
inner side only.
❖ In hill road (Sharp turn), maximum amount of
extrawidening is provided at centre of the circular
curve.

Er. Sabin Pokhrel

Extra Widening [Q.1]
Calculate the extra widening required for a pavement of width 7
meters on a horizontal curve of radius 250 m, if the longest wheelbase
of vehicle expected on the road is 6.0 m. Design speed is 70 Kmph.
Given,
Speed (V) = 70 Kmph Radius of curve (R) = 250 m
Length of wheelbase (l) = 6.0 m
Width of road = 7 m (i.e.; number of lane n = 2)

We have,
Total widening, We = Wm+WPs
𝒏 𝒍𝟐 𝑽
𝑾ⅇ = +
𝟐𝑹 𝟗. 𝟓 𝑹

𝟐∗𝟔.𝟎𝟐 𝟕𝟎
= +
𝟐∗𝟐𝟓𝟎 𝟗.𝟓 𝟐𝟓𝟎
= 0.144 + 0.466 = 0.61 m
As per NRS-2070, extra widening required for radius 100-300 m on double la
calculated We is sufficient for this curve.
189

Number of lane (n) = (Width of the road/3.5)

= (7/3.5)
=2

Er. Sabin Pokhrel

 Vertical Curve
190

Q. Define Vertical curve. Express the relationship between

design length of vertical curve. (1+4)
Answer:
➢ Vertical curve are of two types i.e.

(I) Summit Curve (Crest Curve):

➢ The curve having convexity upward is known as
summit curve.
(II) Valley Curve (Sag Curve):
➢ The curve having convexity downward is known as
valley curve

Er. Sabin Pokhrel

191

Er. Sabin Pokhrel

192

Er. Sabin Pokhrel

193

Xm Q If an Ascending gradient meets with another

descending gradient , then the curve formed is:
(a) Summit Curve

(b) Valley Curve

(c) Transition curve

(d) All of the above

Er. Sabin Pokhrel

194

Xm Q If an descending gradient meets with another

ascending gradient , then the curve formed is:
(a) Summit Curve

(b) Valley Curve

(c) Transition curve

(d) All of the above

Er. Sabin Pokhrel

195

Q If an descending gradient meets with another

ascending gradient , then the curve formed is:
(a) Sag Curve

(b) Valley Curve

(c) Transition curve

(d) Summit Curve

Er. Sabin Pokhrel

196

Q If an descending gradient meets with another

ascending gradient , then the curve formed is:
(a) Sag Curve

(b) Valley Curve

(c) Both (a) and (b)

(d) Summit Curve

Er. Sabin Pokhrel

197

N= Deviation angle i.e. Algebraic difference between

the grades

Er. Sabin Pokhrel

198

U.P.S.C.
Q If an Ascending gradient n1 meets with another
descending gradient n2, then the deviation angle
formed is:
(a) n1+n2

(b) n1-n2

(c) n2-n1

(d) -n1-n2 N = +n1-(-n2)

(a) = +n1 +n2

Er. Sabin Pokhrel

199

➢ Ascending gradient or Upgrade or Uphill = Positive

Sign (+)
➢ Descending gradient or Downgrade or Downhill =
Negative (-)

Er. Sabin Pokhrel

200

U.P.S.C.
Q If an descending gradient n1 meets with another
ascending gradient n2, then the deviation angle
formed is:
(a) n1+n2

(b) n1-n2

(c) n2-n1

(d) -n1-n2 N = -n1-(+n2)

(a) = -n1-n2

Er. Sabin Pokhrel

201

Q. If an ascending gradient 5 % meets with another

descending gradient 4 %, then the deviation angle
is:
(a) – 1 %

(b) +1%

(c) 5 %

(d) 9 %

Er. Sabin Pokhrel

202

(I) Summit Curve:

❖ Simple parabolic curves are generally preferred
for summit curves.
(A) Length of Summit Curve (L) for SSD:
(a) When L> SSD

Er. Sabin Pokhrel

203

Note:
➢ Height of Eye level of driver above the pavement
surface (H) = 1.2 m (120 cm)
➢ Height of obstacle above the pavement surface (h) =

0.15 m (15 cm)

➢ Height of headlight above the pavement surface (h1) =
0.75 m (75 cm)
In Airport:
➢ Height of eye level of pilot above the runway = 3 m

Er. Sabin Pokhrel

204

Er. Sabin Pokhrel

207

Xm. Q During overtaking process, the height of

obstacle above the road surface is:
(a) 10 cm (c) 100 cm
(b) 15 cm (d) 120 cm
Q. During stopping process, the height of obstacle
above the road surface is:
(a) 10 cm (c) 100 cm
(b) 15 cm (d) 120 cm

Er. Sabin Pokhrel

208

Q. In highway , the height of obstacle above the road

surface is:
(a) 10 cm (c) 100 cm
(b) 15 cm (d) 120 cm

Er. Sabin Pokhrel

 Valley Curve
209

Valley curve is designed based on following two

conditions:
(I) Based on passenger’s comfort condition
Length of valley curve (Ls) = 0.38(NV³)⋀½
Where, N = deviation angle (i.e. Algebraic
difference between the grades)
V = design speed (kmph)

Er. Sabin Pokhrel

 (II) Based on Headlight sight distance:
210

When L>SSD

Er. Sabin Pokhrel

 Highway Drainage
211

➢ There are two types of drainage system:

(I) Surface Drainage System
(II) Sub-surface drainage system

➢ The drainage at the surface of the ground is

known as Surface drainage system.
➢ The drainage below the surface of the ground is
known as sub-surface (Subgrade) drainage system

Er. Sabin Pokhrel

212

➢ On hill road, drains are provided at hill side only

(only one side).
➢ On box cutting, drains are provided at both sides
of the roads.

Er. Sabin Pokhrel

 Highway Drainage (Requirements)
213

Q. What are the requirements of highway drainage? (5 marks)

➢ Road surface if made of soil, gravel or WBM roads becomes soft and looses its
strength upon the application of water.
➢ Continuous contact of bituminous roads with water detaches the aggregates from
bitumen.
1. Surface water from carriageway should be drained off effectively without
percolating to the subgrade.
2. Surface water from adjoining area should not be allowed to enter the roadway.
3. Side drain should have sufficient capacity and longitudinal slope for all surface
water collect
4. Seepage & other sources of groundwater should be drained off by sub-surface
drainage.
5. Highest level of groundwater table should be kept below the subgrade at least
1.2m
6. Special precautions should be taken in water logged areas.

Highway Drainage 7/20/2024

 Road Pavement
214

Q. What are the components of road pavement ?

Explain in brief about types of pavement. (2+3)
❖ A road consists of following components:

(a) Wearing course (c) Sub-base Course

(b) Base Course (d) Sub-grade

➢ Wearing Course is also known as Top course or

surface course or topmost course.
➢ Sub-grade is also known as bottom most course.

Er. Sabin Pokhrel

 Components of Pavement
215

Er. Sabin Pokhrel

 Types of Pavement
216

(1) Flexible Pavement (3) Rigid Pavement

(2) Semi-rigid Pavement (4) Composite Pavement
❖ Flexible pavement is made up of bitumen in the
surface course
❖ The lime, fly-ash, soil stabilization in wearing course
in semi-rigid pavement
❖ The rigid pavement consists of cement concrete, RCC
or pre-stressed concrete in surface course
❖ Composite pavement is the combination of above
types of pavement.

Er. Sabin Pokhrel

217

Xm Q The minimum thickness of base course is:

(a) 15 cm (c) 25 cm
(b) 20 cm (d) 30 cm
Q The minimum thickness of base course is:
(a) 10 cm (c) 20 cm
(b) 15 cm (d) 25 cm

Er. Sabin Pokhrel

218

Q The minimum thickness of base course is:

(a) 5 cm (c) 15 cm
(b) 10 cm (d) 20 cm
Q The minimum thickness of base course is:
(a) 20 cm (c) 30 cm
(b) 25 cm (d) 35 cm

Er. Sabin Pokhrel

219

Xm The dangerous types of failure is the failure of

(a) Wearing course (c) Sub-base course
(b) Base course (d) Subgrade

Xm. Which of the following is top most layer:

(a) Wearing course (c) Sub-base course
(b) Base course (d) Subgrade

Er. Sabin Pokhrel

220

Xm. Which of the following is bottom most layer:

(a) Wearing course (c) Sub-base course
(b) Base course (d) Subgrade

Xm Which of the pavement is suitable (desirable) for

night driving condition?
(a) Flexible pavement (c) Rigid Pavement
(b) Semi-rigid pavement (d) Composite pavement

Er. Sabin Pokhrel

221

Xm The types of Pavement depends upon the:

(a) Wearing Course
(b) Base Course
(c) Sub-base course
(d) Subgrade
Xm The types of flexible and rigid Pavement depends upon
the:
(a) Wearing Course
(b) Base Course
(c) Sub-base course
(d) Subgrade

Er. Sabin Pokhrel

Q. If the thickness of wearing course is 5 cm, base
course is 15 cm, sub-base course is 15 cm and
capping layer is 15 cm, then the thickness of the
pavement is:
(a) 5 cm

(b) 15 cm

(c) 35 cm

(d) 50 cm
223

❑ Types of pavement depends upon wearing course.

❑ Design of pavement depends upon base course.
❑ Strength of pavement depends upon sub-grade.

Er. Sabin Pokhrel

 Road maintenance and Repair
224

❖ Measures intended to keep the pavement structure

in serviceable condition as best as practicable and
as long as possible is known as maintenance.
Types of Maintenance:
(1) Routine Maintenance

(2) Recurrent Maintenance

(3) Periodic Maintenance

(4) Emergency Maintenance

Er. Sabin Pokhrel

225

(1) Routine Maintenance:

➢ Routine maintenance is carried out daily at road,
below road or above road.
➢ The works done in routine maintenance are grass
cutting of shoulders, cleaning of road & drain,
cleaning of sign post, pot holes repair of earthen
and gravel road, etc
(2) Recurrent Maintenance:
➢ Recurrent maintenance is carried out at the interval
of 6 months to 2 years.
Er. Sabin Pokhrel
226

➢ The works done in Recurrent maintenance are pot

holes repair of bituminous road, painting of road
marking & sign posts, repair of drainage , etc
(3) Periodic Maintenance:
➢ It is carried out at the interval of 5 to 7 years.

➢ The works done in periodic maintenance are

overlaying of road, Bio-Engineering, installation of

cross drainage structures like culverts , etc.

Er. Sabin Pokhrel

227

(4) Emergency Maintenance:

➢ It is also known as special maintenance.

➢ It is carried out in a emergency situations.

Er. Sabin Pokhrel

228

Xm. Q. Pot holes repair of earthen and gravel road

comes under:
(a) Routine Maintenance

(b) Recurrent Maintenance

(c) Periodic Maintenance

(d) Emergency Maintenance

Er. Sabin Pokhrel

229

Xm. Q. Pot holes repair of bituminous road comes

under:
(a) Routine Maintenance

(b) Recurrent Maintenance

(c) Periodic Maintenance

(d) Emergency Maintenance

Er. Sabin Pokhrel

230

Q. Pot holes repair of road comes under:

(a) Routine Maintenance

(b) Recurrent Maintenance

(c) Periodic Maintenance

(d) Emergency Maintenance

Er. Sabin Pokhrel

 Difference between:
231

Er. Sabin Pokhrel

232

Er. Sabin Pokhrel

233

Er. Sabin Pokhrel

Design of flexible pavement by CBR
Value:
➢ The design of flexible pavement with CBR method is
done in two steps:
(I) Calculation of CBR value
(II) Calculation of thickness of pavement
(I) Calculation of CBR value
❖ CBR is the penetration test developed by California
Division of Highways.
❖ This test is done for calculating the stability of soil
subgrade and other flexible pavement materials.
➢ CBR (%) = (Load sustained by the specimen at 2.5
or 5 mm penetration)/(Load sustained
by the standard aggregates at the
corresponding penetration value) * 100 %
➢ The CBR values of 2.5 mm penetration is higher than
that of 5 mm
➢ If the CBR values of 5 mm penetration is higher than
that of 2.5 mm, then the test is repeated.
➢ Three test is conducted and the average of three is CBR
values
236

Q. In CBR test , the penetration is given for:

(a) 2.5 mm

(b) 7.5 mm

(c) 10 mm

(d) 15 mm

Er. Sabin Pokhrel

237

Q. In CBR test , the penetration is given for:

(a) 0.5 mm

(b) 5 mm

(c) 6 mm

(d) 7.5 mm

Er. Sabin Pokhrel

238

Q. In CBR test , the penetration is given for:

(a) 2.5 mm

(b) 5 mm

(c) Both of above

(d) 7.5 mm

Er. Sabin Pokhrel

(II) Calculation of thickness of pavement:
❖ The thickness of pavement is obtained by using the
formula:
❖ t = ((1.75P/CBR ) – (A/π))½

Where,
t = thickness of pavement (cm)
P = Wheel load (kg)
CBR = California Bearing Ratio (%)
A = Contact area (cm2)
Typical Flexible Pavement Failure
(1) Alligator (Map) Cracking
(2) Consolidation of Pavement Layers
(3) Longitudinal Cracking
(4) Frost Heaving
(5) Lack of Binding with lower layers
(6) Reflection Cracking
(7) Formation of waves and
corrugation
Typical Rigid Pavement Failure
(1) Scaling of Cement Concrete
(2) Shrinkage Cracks
(3) Spalling of Joints
(4) Warping Cracks
(5) Mud Pumping
248

Xm. Q. Which of the failure is typical types of

flexible pavement failure?
(a) Scaling of cement concrete

(b) Shrinkage cracks

(c) Waves and Corrugations

(d) All of above

Er. Sabin Pokhrel

249

Q. Which of failure is typical types of flexible

pavement failure?
(a) Alligator cracking

(b) Crocodile cracking

(c) Both of above

(d) Scaling of cement concrete

Er. Sabin Pokhrel

250

Xm. Q. Which of the failure is typical types of rigid

pavement failure?
(a) Waves and Corrugation

(b) Alligator cracking

(c) Mud pumping

(d) All of above

Er. Sabin Pokhrel

 Test of Highway Materials (Road
251
Aggregate)
(1) CBR test
(2) Abrasion test
(3) Crushing Strength test
(4) Water Absorption test
(5) Soundness test
(6) Impact test

Er. Sabin Pokhrel

252
Test of Highway Materials…
(1) CBR test:
❖ CBR test is the penetration test developed by the
California division of Highway.
❖ It is the method for evaluating the stability of soil
subgrade and other flexible pavement materials

Er. Sabin Pokhrel

253
Test of Highway Materials…
(2) Abrasion Test:
❖ Abrasion test is performed for measuring the abrasion
resistance of aggregates.
❖ This test is commonly used to evaluate the hardness of
the aggregate
❖ Some of the abrasion test are:

(1) Los Angeles Abrasion test

(2) Dory Abrasion test

(3) Deval attrition test

❖ Los Angeles Abrasion test is the most popular one.

Er. Sabin Pokhrel
254
Test of Highway Materials…
(3) Crushing Test:
❖ The aggregate crushing value gives a measure of the resistance of
an aggregate to the crushing under a gradually applied
compressive load.
❖ Aggregates with a lower crushing value indicates a lower crushed
fraction under load and would give a longer service life.
❖ 40 tonnes compressive load @4 ton/minute

(4) Impact test:

❖ Aggregates with lower impact value are hard and aggregates with
higher impact value are weaker.
❖ (13.5 – 14) kg hammer and free fall height of 380+-5 mm, 15
times free fall

Er. Sabin Pokhrel

255
Test of Highway Materials…
(5) Water Absorption test:
❖ Higher water absorption means more voids which results less
strength of aggregates.
❖ The aggregates should not absorb water more than 0.6 %
by weight of the aggregates.
(6) Soundness test:
❖ Soundness test is intended to study the resistance of
aggregates to weathering action.
❖ The total weight loss of aggegate incase of sodium sulphate
should not be greater than 12 %.
❖ The total weight loss of aggegate incase of Magnesium
sulphate should not be greater than 18 %.

Er. Sabin Pokhrel

 Testing Of Bitumen
256

(1) Penetration Test:

❖ It determines the hardness or softness of the bitumen
(2) Softening Point Test:
❖ The softening point is the temperature at which
substance attains a particular degree of softening
under specified condition of test.
(3) Ductility test
❖ Ductility is the property of bitumen that permits
elongation. (i.e. distance in cm)

Er. Sabin Pokhrel

 Grade of Bitumen
257

✓ In Nepal 80/100 grade of bitumen is widely used.

✓ 80/100 grade of bitumen indicates that its
penetration value lies between 8 mm to 10 mm.
✓ In cold regions (Eg: In Solukhumbhu) upto 180/200
grade of bitumen are used to avoid excessive
brittleness.
✓ In hot regions (Eg: In Janakpur) 30/40 grade of
bitumen are used.

Er. Sabin Pokhrel

258
Testing Of Bitumen…
(4) Specific Gravity test:
❖ The specific gravity of bitumen is defined as the
ratio of mass of given volume of bitumen of known
content to the mass of equal volume of water at 27
degree celcius.
❖ The specific gravity of bitumen varies from 0.97 to
1.02
(5) Viscosity test:
❖ Viscosity denotes the liquid property of bituminous
materials and it is a measure of resistance to flow.
Er. Sabin Pokhrel
259
Testing Of Bitumen…
(6) Flash and Fire point test
(7) Water content test:
❖ The allowable maximum water content should not

be more than 0.2 % by weight.

(8) Loss on heating test:
❖ Bitumen used in pavement mixes should not indicate

more than 1 % loss in weight.

Er. Sabin Pokhrel

 Road Construction Technology
260

Step by Step
(1) Preparation of sub-grade

(2) Preparation of Sub-base

(3) Preparation of base

(4) Preparation of wearing course

(5) Preparation of shoulder

(6) Opening to vehicular traffic

Er. Sabin Pokhrel

261

Note: Compaction is done from edge to centre with

the overlap of 30 cm each layer.
Xm. Q Which of the following layer is constructed
first?
(a) Wearing Course

(b) Base Course

(c) Sub-base course

(d) Subgrade

Er. Sabin Pokhrel

 Bridge
262

❖ A bridge is a structure providing passage over an

obstacle without closing the way beneath.
❖ As per NRS-2070, bridge is such a cross drainage
structure whose span length is more than 6 meter.
❖ A cross drainage structure having span length less
than or equal to 6 meter is known as Culvert.
Components of Bridge:
(1) Sub-structure

(2) Super-structure

Er. Sabin Pokhrel

263

Types of Bridge according to the construction

materials:
(a) Stone bridge

(b) Brick bridge

(c) Timber bridge

(d) Iron bridge

(e) Steel bridge

Er. Sabin Pokhrel

264

Types of Bridge according to the function:

(a) Highway bridge

(b) Railway bridge

(c) Pedestrian bridge

Types of Bridge according to obstacle to be crossed:

(a) River bridge

(b) Sky bridge

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265

According to span length and total length of bridge:

(I) Minor Bridge:
➢ Bridge having span length less or equal to 25 m
and total length of bridge less or equal to 50
meter.
(II) Major Bridge:
➢ Bridge having span length more than 25 m and
total length of bridge more than 50 meter.

Er. Sabin Pokhrel

266

Types of bridge according to the alignment:

(a) Straight bridge:

If the axis of the bridge is perpendicular (right angle)

to the direction of river flow, it is known as straight
bridge.
(b) Skew bridge:
If the axis of the bridge is not perpendicular (right
angle) to the direction of river flow, it is known as
skew bridge.
Er. Sabin Pokhrel
 Typical Beam/Girder Bridge
267

5.1 BRIDGE ENGINEERING 7/20/2024

268
Bridge…
T-beam Bridge:
❖ Shape of bridge is T

❖ This type of bridge is suitable for moderate span upto 25

meter i.e generally 10 to 25 meters
Trails and Tracks:
➢ Trails have generally width of 1.25 m

➢ Tracks have generally width of 2.5 m

Trial Bridges:
Types of Trial bridges interms of span: (2 types)
(1) Short Span Trial Bridges (SSTB) : Span upto 120 m
(2) Long Span Trial Bridges (LSTB) : Span more than120 m

Er. Sabin Pokhrel

269

Suspension Bridge Suspended Bridge

It has tower It has not tower

It is (20-25) % more expensive than It is less expensive than suspension

suspended bridge bridge
Walking deck is Hogging type Walking deck is sagging type

Walking deck width is 106 cm ≈100 Walking deck width is 70 cm and 100
cm cm
Both level of bank sholuld be equally Both level of bank may or may not be
levelled equally levelled.
It is of Ancient type It is of latest one

It is also known as N-type bridge It isEr.also

Sabinknown
Pokhrel as D-type bridge
 Provisions of bridge as per Nepal
270
Bridge Standard:
❖ All permanent bridges shall be designed for a design
life of minimum 50 years.
❖ Traffic projections shall be made for a period of 30
years.
❖ All permanent bridges shall be designed for a
discharge of 100 years return period.
❖ All permanent bridges in Nepal shall be designed as
per IRC (Indian Road Congress) loadings or AASHTO
(American Association of State Highway and
Transportation Officials) loadings.
❖ All bridges in Highway and Urban roads shall be
designed with a minimum carriageway width of 7.5 m
Er. Sabin Pokhrel
271
Bridge…
❖ All bridges in Feeder roads shall be designed with
a minimum carriageway width of 6 meter
❖ Minimum Width of footpath = 1 meter (Each side)
❖ Minimum height of railing = 1 meter
❖ Height of raised curbs shall not be less than 20 cm
❖ Width of raised curbs shall not be less than 45 cm
❖ Desirable Width of raised curb = 50 cm
❖ Minimum Free Board (F.B.) = 1 meter

Er. Sabin Pokhrel

272

Xm. Minimum width of footpath on road is:

(a) 1 m (c) 2 m
(b) 1.5 m (d) 3 m
Q. Minimum width of footpath on bridge is:
(a) 1 m (c) 2 m
(b) 1.5 m (d) 3 m
Xm Q. Minimum width of footpath required is:
(a) 1 m (c) 2 m
(b) 1.5 m (d) 3 m
Er. Sabin Pokhrel
 Road Machineries (Earth Moving and
273
Compacting Equipments)
Earth moving Equipments
1) Excavator
2) Dozers
3) Power shovel
4) Back Hoe Loader
5) Drag lines
6) Clamshells
7) Trench Digger
8) Scrappers
Er. Sabin Pokhrel
 Equipment for Compaction
274

1) Smooth wheel roller

2) Sheep footed roller
3) Grid roller
4) Vibrating roller
5) Tandem/Tamping roller
6) Pneumatic tired roller
7) Frog Hammer
8) Plate Compactor
9) Hand Held roller
Er. Sabin Pokhrel
 Parking
275

➢ The space where leisure vehicles are kept is known

as parking.
➢ There are two types of parking i.e On-street
parking and Off-street parking.
➢ In On-street parking, vehicles are parked at road.
➢ On street parking is also known as Curb parking
➢ In off-street parking vehicles are parked away from
road

Er. Sabin Pokhrel

 Parking
276

(a) Parallel Parking

(b) Angular Parking
❖ Parallel parking is preferred when the width of
street are limited.
❖ Maximum vehicles can be parked at an angle of
90 degrees.
❖ Drivers prefer parking at an angle of 75 degrees
❖ From all considerations, 45 degree angle parking
is the best.

Er. Sabin Pokhrel

 Parallel Parking
277

Er. Sabin Pokhrel

 Angular Parking
278

Er. Sabin Pokhrel

279

Style of Off-street Parking:

(A) Self-parking:

➢ The vehicles are parked by drivers or owners.

(B) Attendant parking (Valet Parking)
➢ The vehicles are parked by attendant.

Er. Sabin Pokhrel

 Types of Off-street Parking:
280

(1) Surface Car Parking

(2) Multi-storey parking
(3) Roof Parking
(4) Underground Parking
(5) Mechanical Car Parking

Er. Sabin Pokhrel

 Surface Car Parking
281

Er. Sabin Pokhrel

 Multi-storey Car parking
282

Er. Sabin Pokhrel

 Underground Parking
283

Er. Sabin Pokhrel

 Mechanical Parking
284

Er. Sabin Pokhrel

 Roof Parking
285

Er. Sabin Pokhrel

 Effects of Parking:
286

(1) Congestion
(2) Accident
(3) Obstruction to Emergency Vehicles
(4) Environmental Pollution

Er. Sabin Pokhrel

287

Q. If the width of the bay is 25 meter, the number of

vehicles that can be parked at 90 degree is:
(a) 7

(b) 8

(c) 10

(d) 12

Er. Sabin Pokhrel

288

The number of vehicles that can be parked at 90

degree =
(Width of the bay/Design width of vehicle)
= (25 m/2.5 m)
= 10

Er. Sabin Pokhrel

 Hairpin Bend
289

Er. Sabin Pokhrel

290
Hairpin Bend…
❖ Design speed = 20 kmph
❖ Minimum radius of inner curve = 15 m
❖ Minimum radius of curvature = 15 m
❖ Minimum length of transition curve = 15 m
❖ Maximum longitudinal gradient = 4 %
❖ Maximum Super-elevation = 10 %
❖ Straight length between two successive hair pin
bend should be minimum of 60 meter excluding the
length of circular and transition curves.

Er. Sabin Pokhrel

 Alignment selection criteria for hill
291
road:
(1) Deep cutting should be avoided as they are very
difficult and costly.
(2) Rises and falls should be as easy as possible
(3) The alignment of road should be on sound and
solid areas
(4) The alignment of roads should be on that side of
road which remains exposed to sun for most of the
time in winter. This helps easy melting of snow.
(5) There should be provision of surface as well as
sub-surface drainage system
Er. Sabin Pokhrel
292

(6) Sight distance should be atleast equal to Stopping

sight distance.
(7) Wider stretch of road should be provided on
certain section of roads so that overtaking of
vehicles and parking could be done.
(8) The radius of curve should be such that longest
vehicle expected to use that road section would turn
easily.
(9) For the safety of road users, parapet walls should
be constructed on the outer side of the roads.
Er. Sabin Pokhrel
 Construction Problems of Hill Roads:
293

(1) There are abrupt rises and falls in the hill roads.
(2) The road stable before construction changes to
unstable after construction due to soil erosion and
landslides.
(3) There are numerous number of sharp turning
including Hair pin bends
(4) Huge number of cross drainage structures like
culvert, causeway,etc are required.
(5) Special types of cross drainage strucures like
Aqueduct are required in Hill roads.
Er. Sabin Pokhrel
294

(6) Special measures like Bio-Engineering are

required in Hill roads.
(7) More height of retaining walls are required in Hill
roads.
(8) In ridge routes, there are lack of construction
materials like stone, coarse aggregate, fine
aggregates, water,etc.
(9) Due to snow fall in the hill road, the road damages
time and again.
Er. Sabin Pokhrel
 Traffic Sign
295

➢ The lower disk of the traffic sign should be 2 meter

above the road surface.
➢ Traffic sign should be placed 45 cm beyond the
road edge and desirable is 60 cm

Er. Sabin Pokhrel

 Traffic Sign
296

(I) Regulatory or Mandatory Sign:

❖ A01-A33 types of signs
❖ Denoted inside a circle
❖ Always red border, black symbol and white
background

Er. Sabin Pokhrel

297
Traffic Sign…
(II) Warning or Cautionary Sign
❖ B01-B48 types of signs

❖ Apex pointing upward

❖ Triangular shape (Equilateral triangle ) of:

60 cm for Highway, Feeder roads

45 cm for village roads, agricultural roads, Rural roads
etc

❖ Red border, black symbol and white background

Er. Sabin Pokhrel

298
Traffic Sign…
(III) Informatory Sign
❖ Rectangular Shape

Er. Sabin Pokhrel

299

Xm The background colour of informatory sign is:

(a) Yellow (c) White
(b) Green (d) Blue
Note:
As per NURS-2076 BS, informatory sign has green
background and white symbol .

Er. Sabin Pokhrel

 Traffic Signal
300

Er. Sabin Pokhrel

301

G = Green = Go
R = Red = Stop
Y = Yellow or Amber = Clearance time
➢ Clearance time is 3 seconds to 5 seconds.

➢ Pedestrian Signal:
➢ Green Walking man = GO
➢ Green Flashing man = Go fast
➢ Red Standing man = Stop
Er. Sabin Pokhrel
302

Q. “GO” in pedestrian signal represents:

(a) Green Walking man

(b) Green Walking woman

(c) Both of above

(d) Red standing man

Er. Sabin Pokhrel

 Cross Drainage Structures
303

➢ A structure provided to cross the water from one

side of road to the other side of road or from uphill
side of road to the downhill side of road is known as
cross drainage structures.

Highway Drainage 7/20/2024

 Types of cross drainage structures
304

(I) Culverts
(II) Fall or drop structures
(III) Causeway
(IV) Aqueduct
(V) Inverted Siphon
(VI) Bridge

Highway Drainage 7/20/2024

 Types of Culvert:
305

Pipe culvert
Slab Culvert
Box Culvert
Arch Culvert

Highway Drainage 7/20/2024

 Pipe culvert
306

Highway Drainage 7/20/2024

 Slab culvert
307

Highway Drainage 7/20/2024

 Box culvert
308

Highway Drainage 7/20/2024

 Arch culvert
309

Highway Drainage 7/20/2024

 Suitability of types of culverts:
310

• Slab Culvert: Perennial or non perennial stream with boulder

movement & debris flow.
• Pipe Culvert: In non perennial or at very small stream,
frequently provided to carry surface run-off from side drain.
• As per road standard of Nepal, minimum size of pipe culvert
should be at least 60 cm internal diameter.
• Arch Culvert: In high hills, deep cuts.
• Box culvert: to serve large flow, where the boulder movement
occurs, they are RCC thus resists high impact loads.
• The minimum size of box culvert should be atleast 60 cm * 60
cm
Highway Drainage 7/20/2024
 Pipe culvert
311

Mainly it consists of three parts:

 Culvert barrel

 Inlet structure

 Outlet structure

Highway Drainage 7/20/2024

 Elements of culvert
312

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313

Highway Drainage 7/20/2024

314

❑ Backfilling of culvert should be atleast 50 cm so

that traffic vibration would be minimum at Culvert.
 Depending upon the type of soil foundation there
may be either sand bedding or PCC or RCC.
 Inlet or outlet structure consists of apron.
 Additional elements like hand rail, parapet wall
may be provided.

Highway Drainage 7/20/2024

315

Fall or Drop Structure:

• They are provided both upstream & downstream of

cross drainage.
• Different types of drop structures:

• a) Drop without stilling basin and friction wall

• b)Drop with stilling basin

• c) Drop with frictional wall

• d) Drop with frictional wall and stilling basin

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316

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317

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318

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319

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320

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 Causeways:
321

➢ A cross drainage structure with or without openings below road surface

provided across a shallow drainage course at or about the bed level which
allows floods/ runoff to pass over it is referred as Causeway.
– A causeway with vents below to pass regular flow under the
road and flash flood across the road surface is often known
as high level causeway or submersible bridge.

– A causeway constructed at bed level which allows flood to

pass over the road surface at any time is referred as flush
causeway. It is sometimes called as Ford.

Highway Drainage 7/20/2024

 Causeway
322

Highway Drainage 7/20/2024

 Causeway
323

Highway Drainage 7/20/2024

 Low level causeway
324

➢ For most of the time in year, the maximum depth of

flow should not be greater than 150 mm.
➢ Bed slope of low level causeway should not be
greater than 4 %.
➢ There should be regular provision of cleaning of
debris of causeway.
➢ Total interruption in a year in Village road should
not be greater than 15 days.
➢ Total interruption in a year District road should not
be greater than 10 days
Er. Sabin Pokhrel
 Vented Causeway (High Level
325
Causeway or Submergible Bridge)

Highway Drainage 7/20/2024

326

Highway Drainage 7/20/2024

 High level causeway
327

➢ The causeway in which normal water flow passes

below the road and occasional flash flood passes
over the road is known as High level causeway.
➢ Total interruption in a year in Village road should
not be greater than 15 days.
➢ Total interruption in a year District road should not
be greater than 3 days
➢ Design flood period = 10 years.

Er. Sabin Pokhrel

328

Bank protection spur

 Spur (groynes): perpendicular structure to the
direction of flow to dissipate the water energy &
protect the erosion.

Highway Drainage 7/20/2024

329

5.1 BRIDGE ENGINEERING 7/20/2024

330

Aqueduct:
A cross drainage structure provided to cross the water
above the road is known as aqueduct.
Inverted Siphon:
A cross drainage structure provided to cross the water
below the road is known as Inverted Siphon

Er. Sabin Pokhrel

HILL ROADS:

Typical Cross-section of Hill Road

The cross section of a road in a hilly terrain is determined by the
original ground slope of the site, the slope of the road formation,
width of roadway, side drain size, and shape and so on. Various
types of road cross-section are:
1) Cut and fill
2) Bench type
3) Box cutting
4) Embankment with retaining walls
5) Semi bridge
6) Semi tunnel
7) Platforms

331
HILL ROADS:

Bench Type
▪ If the side slope is greater, it is
difficult to fill the embankment
and compaction is also difficult.
Bench type cross section is the
3. Typical Cross-section of Hill
most suitable.
Road
▪ some increase in earthwork but
Cut and fill ensures the complete stability of
▪ Cheaper and environment the road-bed, if hill side is itself
friendly. stable.
▪ Less earthworks.

332
HILL ROADS:

Embankment with Retaining

Wall
3. Typical Cross-section of Hill
Road
Box Cutting
▪ When the location of road-bed is
unstable or unsuitable along the
hillside, the road-bed is designed
as trench type of cross section.
▪ It increases earthwork to a large
extent.
▪ Drainage provided on both sides.

333
HILL ROADS:

Semi Tunnel
▪ When cutting into steep hills in
stable hard rock, the rock may be
permitted to overhang.
3. Typical Cross-section of Hill
Road
Semi-Bridge
▪ If road is located across step
slope, retaining wall may have to
be very high. In such cases semi
bridge may be constructed.

334
HILL ROADS:

3. Typical Cross-section of Hill Road

Platform:
On the precipitous slopes, where shifting of the route into the
hillside will lead to enormous rock works which eventually increases
the cost and where semi-tunnel cannot be constructed, platforms
are usually cantilevered out of the rock on which roadway is partially
located.

335
 Bituminous Materials
336

❖ Bituminous binders used in road pavement

construction include bitumen and tar.
❖ Bitumen is a petroleum product obtained by the
distillation of petroleum crude where as road tar is
obtained by the destructive distillation of coal and
wood
(1) Bitumen:

❖ Bitumen is a viscous liquid or solid material black

or dark brown in color having adhesives
properties consisting essentially of hydrocarbons.
Er. Sabin Pokhrel
 Types of Bitumen
337

(a) Natural Bitumen

❖ Extracted from natural rock or native asphalt.

(i) Natural rock Asphalt

❖ Deposits of sandstone or limestone naturally.
(ii) Native Lake Asphalt:
❖ Found in depression in earth’s surface which have
accumulated in lakes

Er. Sabin Pokhrel

338
Types of Bitumen…
(b) Petroleum Bitumen:
❖ By product of the fractional distillation at petroleum

refinery plant
Note:
➢ Bitumen is dissolved in Carbon disulphide or carbon
tetrachloride.
➢ Bitumen should be heated at the temperature of

150 to 177 degree celcius.

Er. Sabin Pokhrel

 Cutback Bitumen
339

❖ Cutback is defined as a bitumen whose viscosity has

been reduced by the addition of a volatile diluents.
❖ Volatile diluents are gasolene, kerosene and high
boiling light oils.
Types of Cutback:
(1) Slow curing (Bitumen + Non-volatile materials)

(2) Medium curing (Bitumen+Kerosene)

(3) Rapid curing (Bitumen+ Naphtha)

Er. Sabin Pokhrel

 Tar
340

❖ Tar is the viscous liquid obtained when natural organic

materials such as wood and coal carbonized or
destructively in the absence of air.
❖ Based on the material from which tar is derived, it is
referred as wood tar or coal tar.
❖ Coal tar is widely used for road work because it is
superior to wood tar.
❖ Types of tar ( 5 types)

❖ RT-1 to RT-5

(1) Road Tar-1 (RT-1) : Low viscosity

(2) Road Tar-5 (RT-5) : Highest viscosity

Er. Sabin Pokhrel

341

Q. Which of the following road tar has highest

viscosity?
(a) RT-1

(b) RT-2

(c) RT-4

(d) RT-5

Er. Sabin Pokhrel

342

Q. Which of the following road tar has highest

viscosity?
(a) RT-1

(b) RT-2

(c) RT-3

(d) RT-4

Er. Sabin Pokhrel

343

Q. Which of the following road tar has highest

viscosity?
(a) RT-1

(b) RT-2

(c) RT-4

(d) None of the above

Er. Sabin Pokhrel

 Traffic Flow Characteristics
344

Traffic flow maneuvers

Er. Sabin Pokhrel

 LOS
345

➢ LOS stands for Level of Service

➢ LOS is the qualitative measure used to relate the
quality of traffic service based on performance
measure like speed, density, flow,etc.
➢ There are 6 LOS

(i) LOS-A = Free flow traffic

(ii) LOS-B = Steady traffic
(iii) LOS-C = Steady traffic but limited
(iv) LOS-D = Steady traffic at high density
(v) LOS-E = Traffic at saturation
(vi) LOS-F = Congestion (Jam)
Er. Sabin Pokhrel
346

➢ It is recommended to adopt a LOS-B for the design

capacity of roads in Nepal.
➢ At LOS-B, volume of traffic will be around 45 % of
the maximum capacity under mixed traffic
condition.

Er. Sabin Pokhrel

347

Q. Which of the following is traffic flow maneuver ?

(a) Diversing

(b) Merging

(c) Crossing

(d) All of the above

Er. Sabin Pokhrel

348

Origin and Destination Study ( O & D Study)

❖ The O & D studies of vehicular traffic determines

their numbers & destination in each zone under

study.
❖ The data may also be the number of passengers in

each vehicle , purpose of each trip, intermediate

stops made & reasons etc.
❖ O& D study gives information like actual direction
of travel, selection of route & length of the trip.
Er. Sabin Pokhrel
 Methods of O-D Survey
349

# Roadside Interview Method,

# Registration Number Method,
#Tag or Sticker Method,
#Return Post Card / or Mail Return Method,
# Home Interview Method
# Commercial Vehicle survey
# Taxi Survey

Er. Sabin Pokhrel

350

Q. Which of the following is more reliable survey?

(a) Registration Number Method

(b) Tag or Sticker Method

(c) Home Interview Method

(d) Roadside Interview Method

Er. Sabin Pokhrel