Traversing Notes |surveying II | Sudip khadka

Course Contents:-
1.0 Traversing 6 Hours
1.1 Principles and importance of traversing, types of traverse
1.2 Field works for traversing and booking of field notes
1.3 Reduction of reading to angle and bearing
1.4 Angular misclosure and Closing Error
1.5 Traverse adjustment and computation for closed and link traverse -Gale's Table
1.6 Plotting of traverse survey
1.7 Omitted measurements in traversing
1.8 Instructions to field applications
2. Tachometry 5 Hours
2. l Definitions
2.2 Principle of optical distance measurements
2.3 Systems of tacheometric measurements-Stadia method and tangential method using vertical staff
2.4 Subtense bar
2.5 Booking and plotting of details
2.6 Sources of errors and precision of tacheometric survey
2.7 Instruction on field work
3. Trigonometric Leveling 4 Hours
3.1 Problems of heights and distances
3.2 Plane and geodetic trigonometric leveling
3.3 Significance and error ratio
3.4 Instruction on field applications

4. Contouring 4 Hours
4.1 Introduction
4.2 Contour interval and characteristics of contours
4.3 Method of contouring (direct and indirect)
4.4 Interpolation of contours
4.5 Use of contour map
4.6 Instruction on field works
5. Orientation 3 Hours
5.1 Introduction
5.2 Analytical intersection and resection
5.3 Two point and three point problems and their significance
5.4 Use of geodetic control points
6. Curves 10 Hours
6.1 Classification of curves and their common uses
6.2 Elements of simple circular curves
6.3 Setting out of simple circular curves by ordinate from long chord, by offset from tangents and by deflection
angle methods
6.4 Geometry of transition curves and their elements
6.5 Elements of vertical curves and computation of reduced levels of points on curve

7. Triangulation and Trilateration 4 Hours
7.I Introduction
7.2 Principal of triangulation
7.3 Purpose of triangulation
7.4 Classification of triangulation
7.5 Layout of triangulation
7.6 Fieldwork of triangulation
8. Photogrammetry and Remote Sensing 3 Hours
8.1 Introduction to photogrammetry as a branch of surveying
8.2 Types of aerial photographs
8.3 Scale of vertical photograph
8.4 Relief displacement
8.5 Merits and limitations of photograrmnetry
8.6 Introduction to remote sensing
9. Field Astronomy and GPS System 2 Hours
9.1 Celestial sphere and spherical triangle
9.2 Characters of spherical triangles
9.3 Merits of field astronomy and GPS system for horizontal control in civil engineering problems
10. EDM 2 Hours
10.1 Basic definition
10.2 Classification of EDM instruments
10.3 Principle of Electronic Distance Measurement

11. Total Station 2 Hours
11.1 Introduction
11.2 Features of total station
11.3 Electronic data recording
11.4 Summary of total station characteristics
11.5 field procedures for total station in topographical surveying

PURBANCHAL UNIVERSITY
B.E. (CIVIL ENGINEERING)
SYALLABUS
PURBANCHAL UNIVERSITY
B.E. (CIVIL ENGINEERING)

CHAPTER:- 1
TRAVERSING
Introduction
• The methods of establishing control points in surveying are:
triangulation, trilateration, intersection, satellite position fixing and
traversing.
• Common method: Traversing
• A traverse is a series of connected survey lines of known lengths and
directions or it can be defined as series of lines connecting control
points on ground.
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Function
To provide reference frame work for measurement of whole site.
To provide horizontal and vertical control for all measurements.
Use of traverse control points
In engineering surveying traverse points are used as
control for
• Surveying topographic detail.
• cadastral Survey to lay out property boundaries.
• Setting out engineering Works.
• Aerial survey (Photogrammetric survey).
• Alignment survey
In traversing the positions of points are fixed by measuring horizontalangles, at each
station, subtended by the adjacent stations and the horizontal distance between
consecutive pairs of stations.
The angles define the shape of the network, the lengths establish the scale.

Precision of traversing
For Horizontal control : HZ angle and HZ distance measurement

Where distance of closed loop
K in KM
M in Mile
For vertical control : Rl transfer by levelling

Principle of Traversing
Each leg of traverse can be resolved in to two
components.
• Latitude
The northing component of leg.
θ Lat = L cosθ
• Departure
The easting component of leg.
Depart = Lsinθ
L = length of leg
θ = Bearing of leg

Calculation of coordinate :
Northing of B = Northing of A + latitude of AB
Easting of B = Easting of B + Departure of AB

Type of Traverse:
1) Depending on priority
a) major travers : provide control for whole site
c) Minor traverse: provide control for any part with respect to
Major traverse.
2) Depending on Nature
a) closed traverse
b) open traverse
c) Link traverse

E
B
Closed traverse
• Start from a point and end at same point.
A
D
C
Anti clockwise traverse:
Measure internal angle
Clockwise traverse: measure external angle

Characteristics
• Sum of measured angle = (2n± 4) 90
• ∑ L = 0
∑ D = 0
• ∑ BS - ∑ FS = 0
Advantage:
Error can be calculated, checked and
corrected.
Use:
In topographic survey as Major traverse.
Open traverse
Start from a point and end at another unknown point.
Disadvantage: error can not be calculated
Use: for alignment survey of road and canal.

Link traverse
• Start from a known point and end at another known point, geometrically
closed but mathematically closed.
• Characteristics:
 Sum of angle = FB of last known line - FB of Initial known line - n x 180
∑L = Northing of last point – Northing of first point
∑D = Departure of last point – Departure of first point
 ∑ BS -∑FS = Rl of last point – Rl of first point
• Advantage:
Error can be calculated, checked and distributed.

Field procedure of Traversing
1) Reconnaissance ( reccy)
walking throughout site to observe complexity of site and to decide
tentative position and number of control points for whole site.
2) Selection of station
Criteria:
• Two adjacent station should be accessible from each station.
• Leg ration should be maintained .
Longest leg/ shortest leg ≤ 3 for minor traverse
≤ 2 for close traverse
• All details of site can be measured.
• Minimum station
• Deflection angle ≤ 20 degree
• Workable place for station

3) Referencing:
Each station should be measured from three permanent points in site such
that it can be relocated if marking is missed.
4) Field measurement
for Horizontal control:
Included angle : two set for major and single set for minor traverse.
HZ distance: leg measurement.
For vertical control :
RL transfer on each station.
5) Calculation and check of angular and linear miss closure.

Angular miss closure and correction :
• For close traverse
angular error (δ ) = sum of measured angle – geometric sum
precision =± C
corrected angle = measured angle ± δ/ N
• For minor traverse
angular error (δ ) = calculated WCB of last line – measured WCB of last line
precision =± C
corrected WCB = WCB of line ± (δ/ N) x n
N = total number of station
n = 1 (for first), 2, 3 ………..N(for last)

Linear miss closure( closing error) and correction
Cumulative Error due to error in linear measurement of all
leg. AA’ in figure.
Error(e) =
ΔN = error in latitude ( for close traverse = ∑ latitude)
ΔD = error in departure ( for close traverse = ∑Departure)
Precision = e / P
p = perimeter of traverse
Precision should be with in precision of linear measurement
used.

Bearing calculation:
Sum = WCB of AB + θ
A
WCB of BC= sum + 180 if sum < 180
WCB of BC = sum – 180 if sum > 180
θ WCB of BC = sum – 540 if sum > 540
B
C

Correction of closing error: balancing or traverse
adjustment
It is process of adjusting the latitudes and departures by applying
corrections to them in such a way that the algebraic sum of the latitudes,
and that of the departures should each equal to zero, i.e. the sum of the
northings should be exactly equal to the sum of the southings, and the
sum of the easting should be exactly equal to the sum of the westing.
The methods
1) Bowditch’s method
2) Transit rule
3) Graphical Method

(1) Bowditch’s Rule:
It is also known as the compass rule
It is used when the angular and linear measurements
By this rule, the total error in latitude and
Correction to latitude or departure of
rule and is most commonly used in traverse
and linear measurements are equally precise.
latitude and that in departure is distributed in
of any side
traverse adjustment.
precise.
in proportion to the lengths of the sides.
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sides.
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(2) Tansit Rule:
This rule is used to balance the
than the linear measurements,
(i) Correction to departure of any
(ii) Correction to departure of
the traverse when the angular measurement
measurements,
any side
any side
measurement are more precise
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Gale’s table for Traverse computation
station line
included
angle
angular
correction
corrected
angle WCB Length
Consecutive coordinate correction corrected Independent coordinate Adjusted value
latitude =
l cosθ
departure=
l sinθ latitude departure latitude departure Northing Easting WCB Length
sum δ= P = ΔN= ΔE=
angular error = closing error (e)=
precision = precision = e/p

Calculation of Bearing and length from
independent coordinate
N
B
B
ΔE = Easting of B – Easting A
λ
ΔN= Northing of B – Northing Of A
W A E
Distance of AB = )
Angle (λ) = tan-1(
Δ𝐸
)
Δ𝑁
B
S
WCB of line AB = λ if in first quadrant
= 360 – λ if in second quadrant
= 180 + λ if in third quadrant
= 180 – λ if in fourth quadrant
B

Consecutive coordinate or Dependent coordinate
if the coordinate of points are calculated taking just
previous point as origin, then points are known as
Consecutive coordinate.
Ex. The latitude and Departure of AB are consecutive
Coordinate of point B. The latitude and Departure of BC
are consecutive Coordinate of point C.
Independent Coordinate
If the coordinates of all points are calculated taking
A same point as origin , then the coordinate are
Known as independent coordinate.
Local coordinate: if coordinate of origin is assumed
Universal coordinate : if coordinate of origin point is measured
with reference to universal grid using GPS, Resection.
A
A
Latitude
of AB
C C
Latitude of BC
B
Departure of AB B Departure of BC Northing of point B = Northing of A + latitude of AB
D
Easting of point B = Easting of A + departure of AB
Similarly:
Northing of point C = Northing of B + latitude of BC
Easting of point C = Easting of B + departure of BC
E

Plotting method of traverse
• Using parallel meridian method
• Using included angle method
• Using deflection angle method
• Using independent coordinate

Parallel median method
• Using WCB and HZ distance of leg
• Closing error should be distributed by graphical method.
• Use: in compass survey

Included angle method
• Using included angle and HZ distance
• Closing error should be distributed

Deflection angle method
• Using deflection angle and HZ distance
• Use: in open traverse

Using Independent coordinate method
Best Method of traverse plotting.
Follow working from whole to part, prevent accumulation of plotting error.
Use: in closed traverse, Theodolite traversing

Calculation of omitted data( missing data)
Maximum two measured data of closed traverse can be recalculated if missed.
There are three cases of missing data.
1) One leg defected
2) Two adjacent leg defected
a) length of both leg missed
b) length of one leg and WCB of other leg are missed
c) WCB of both legs are missed.
3)The defected legs are not adjacent.
a) length of both leg missed
b) length of one leg and WCB of other leg are missed
c) WCB of both legs are missed.

Case 1: one leg defected
If length and WCB of one leg are missed , they can be calculated using
property of closed traverse.
∑ latitude = 0
l cosθ = x..................... i
∑departure = 0
l sinθ = y… ...................ii
Squaring and adding I and ii
l =
Dividing ii by i
θ= tan-1( )

Case 2: two adjacent leg are defected
• Two leg PQ and PT defected.
• Join Q ant T with dot line.
• Calculate length and WCB of QT taking QRST as close traverse
as in Case 1.
a) Length of PQ and QT are missed
• find angles α,β, and γ using WCB of PQ,QT and PT.
• Use sine rule to find distance of PQ and PT.
b) Length of PQ and WCB of PT are missed.
• Calculate angle α using WCB of PQ and QT.
• Use sine rule to calculate distance of PQ and angles γ and β.
c) WCB of both leg are missed.
• Apply cosine rule to find α,β, and γ since PQ,QT and PT are
known.
• Find WCB of PQ using WCB of QT and α.
• Find WCB of PT using WCB of QT and β.

Case3: two legs are not adjacent
• The leg UT and SR are defected.
• Draw RR’ parallel and equal to TS such
that WCB and Length of RR’ equals to ST.
• Draw TR’ parallel and equal to SR such
that WCB and length of TR’ equals to SR.
• Find length and WCB of UR’ taking close
traverse PQRR’UP.
• Now solve in Triangle UR’T to find miss
data of UT and R’T=RS.
THANK YOU !!!

Traversing Notes |surveying II | Sudip khadka

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