unit 3: compass survey. 2 unit 5: compass traversing & traverse computation topics covered –...

Unit 3:Unit 3:Compass surveyCompass survey

Unit 5: Compass traversing & Traverse computation

2

Topics covered – Compass Topics covered – Compass SurveyingSurveying

Meridian & Bearing - true, magnetic and arbitrary

Traverse - closed, open.

System of bearing - whole circle bearing, Reduced bearing, fore bearing, and back bearing, conversion from one system to another. Angles from the bearing and vice versa.

Prismatic, Surveyor, Silva and Bronton (introduction) compass

Local attraction with numerical problems.

Plotting of compass survey (Parallel meridian method in detail).


3

DefinitionDefinition

Limitation of chain surveying

Angle or direction measurement must

Azimuth, Bearing, interior angle, exterior angle, deflection angle

C

B

A

220 L

250 R

B

CA

θ

ß

1800 + θ-ß

CB

A

ßΦED

γ

α

θ

C

B

A

ßΦ

E

D

γα

θ


4

Compass surveyingCompass surveying

Compass used for measurement of direction of lines

Precision obtained from compass is very limited

Used for preliminary surveys, rough surveying


5

5.1 Meridian, Bearing & Azimuths5.1 Meridian, Bearing & Azimuths

Meridian: some reference direction based on which direction of line is measured True meridian ( Constant) Magnetic meridian ( Changing) Arbitrary meridian

Source: www.cyberphysics.pwp.blueyonder.co.uk

Bearing: Horizontal angle between the meridian and one of the extremities of line

True bearing Magnetic bearing Arbitrary bearing


6


True meridian Line passing through geographic north

and south pole and observer’s position Position is fixed Established by astronomical

observations Used for large extent and accurate

survey (land boundary)

Observer’s position

Geographic north pole

Geographic north pole

Contd…


7


Magnetic meridian Line passing through the direction shown by freely

suspended magnetic needle Affected by many things i.e. magnetic substances Position varies with time (why? not found yet)

Contd…

Assumed meridian Line passing through the direction towards some

permanent point of reference Used for survey of limited extent Disadvantage

Meridian can’t be re-established if points lost.


8

Reduced bearingReduced bearing

Either from north or south either clockwise or anticlockwise as per convenience

Value doesn’t exceed 900

Denoted as N ΦE or S Φ W

The system of measuring this bearing is known as Reduced Bearing System (RB System)

B

A

SΦW S

W E

N

A

BNΦEN

S

EW


9

Whole circle bearing (Azimuth) Whole circle bearing (Azimuth)

Always clockwise either from north or south end

Mostly from north end

Value varies from 00 – 3600

The system of measuring this bearing is known as Whole Circle Bearing System (WCB System) B

A

S

W E

N

3000

B

A

S

W E

N450


10

5.2 Conversion from one system to 5.2 Conversion from one system to otherother

Conversion of W.C.B. into R.B.

S

W E

N

o

Φ

B

θ A

ß

D

αC

Line W.C.B. between Rule for R.B. Quadrants

OAOBOCOD

00 and 900

900 and 1800

1800 and 2700

2700 and 3600

R.B. = W.C.B. = θR.B. = 1800 – W.C.B. = 1800 – ΦR.B. = W.C.B. – 1800 = α – 1800

R.B. = 3600- W.C.B. = 3600- ß.

NθESΦESαESßE


11

5.2 Conversion from one system to 5.2 Conversion from one system to otherother

Conversion of R.B. into W.C.B.

S

W E

N

o

θß

αΦ

B

AD

C

Line R.B. Rule for W.C.B. W.C.B. betweenOAOBOCOD

NθESΦESαESßE

W.C.B. = R.B.W.C.B. = 1800 – R.B.W.C.B. = 1800 + R.B.W.C.B. = 3600- R.B.

00 and 900

900 and 1800

1800 and 2700

2700 and 3600

Contd…


12

5.2 Fore & back bearing5.2 Fore & back bearing

Each survey line has F.B. & B.B.In case of line AB, F.B. is the bearing from A to B B.B. is the bearing from B to A

Relationship between F.B. & B.B. in W.C.B.

θ

1800 + θ ß

ß - 1800

D

CB

A

B.B. = F.B. ± 1800

Use + sign if F.B. < 1800

&

use – sign if F.B.>1 1800


13

5.2 Fore & back bearing5.2 Fore & back bearing

Relationship between F.B. & B.B. in R.B. system

Contd…

NßW

D

C

B

A

SΦWNΦE

SßE

B.B.=F.B.Magnitude is same just the sign changes i.e. cardinal points changes to opposite.


14

5.2 Calculation of angles from 5.2 Calculation of angles from bearing and bearing and vice versa vice versa

In W.C.B.system ( Angle from bearing) Easy & no mistake when diagram is drawn Use of relationship between F.B. & B.B. Knowledge of basic geometry

B

CA

Θ-1800 -ß θ

ß

1800 + θ-ß

ß

θC

A

B


15

5.2 Calculation of angles from 5.2 Calculation of angles from bearing andbearing and vice versa vice versa

In R.B. system (Angle from Bearing) Easy & no mistake when diagram is drawn Knowledge of basic geometry

C

A

B

NθE

SßE

1800-(θ+ß)

Contd…

B

CA

SßESθW

Θ+ß


16

5.2 Calculation of bearing from 5.2 Calculation of bearing from angle angle

Normally in traverse, included angles are measured if that has to be plotted by co-ordinate methods, we need to know the bearing of line Bearing of one line must be measured Play with the basic geometry Diagram is your good friend always

??

?

? Ø


17


=?

Contd…

Bearing of line AB = θ1 Back Bearing of line AB = 1800 + θ1

Fore Bearing of line BC =θ2 = α – = α -[3600 –(1800 + θ1) ] = α+ θ1- 1800

= 3600 – BB of line AB = 3600 -(1800 + θ1)

is also = alternate angle of (1800 – θ1) = (1800 – θ1)


18


=?

Bearing of line BC = θ2

Back Bearing of line BC = 1800 + θ2

Fore Bearing of line CD = θ3 = ß – = ß -[3600 –(1800 + θ2) ] = ß+ θ2- 1800

= 3600 – BB of line BC = 3600 -(1800 + θ2)

Contd…


19


Contd…

?Bearing of line CD= θ3

Back Bearing of line CD = 1800 + θ3

Fore Bearing of line DE = θ4 = γ – = γ -[3600 –(1800 + θ3) ] = γ+ θ3- 1800

= 3600 – BB of line CD = 3600 -(1800 + θ3)

?

Ø


20

5.2 Calculation of bearing from 5.2 Calculation of bearing from angleangle

Contd…

Ø=?

Bearing of line DE= θ4

Back Bearing of line DE = 1800 + θ4

Fore Bearing of line EF = θ5 = BB of line DE + Ø = 1800 + θ4 + Ø


21

5.2 Numerical on angle & bearing5.2 Numerical on angle & bearing

What would be the bearing of line FG if the following angles and bearing of line AB were observed as follows: (Angles were observed in clockwise direction in traverse)

EFG =

DEF =

CDE =

BCD =

ABC =

1240 15’

2150 45’

950 15’1020 00’1560 30’

Bearing of line AB = 2410 30’


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EFG =

DEF =

CDE =

BCD =

ABC =

1240 15’

2150 45’

950 15’1020 00’1560 30’

Bearing of line AB = 2410 30’

A

2410 30’

B

1240 15’

C

1560 30’

D

1020 00’

E950 15’

F

G

2150 45’

?

A

2410 30’

B

1240 15’

1560 30’

D

1020 00’E

950 15’

F

G

2150 45’

C


23


1240 15’

A

2410 30’

B

FB of line BC = (2410 30’- 1800) + 1240 15’ = 1850 45’

FB of line CD = (1850 45’- 1800) + 1560 30’ = 1620 15’

C

B

1850 45’

C

1560 30’

D


24


FB of line DE =1020 00’ - (1800- 1620 15’) = 840 15’

FB of line EF = (840 15’+1800) + 950 15’ = 3590 30’

C

1620 15’

D

1020 00’E

D

840 15’E

950 15’

F


25


FB of line FG =2150 45’ - {1800+(BB of line EF)}

E

3590 30’

F

G

2150 45’

FB of line FG =2150 45’ - {(1800 +(00 30’)} = 350 15’

A

2410 30’

B

1240 15’

1560 30’

D

1020 00’E

950 15’

F

G

2150 45’

C


26


From the given data, compute the missing bearings of lines in closed traverse ABCD.

A =

810 16’

Bearing of line CD = N270 50’E

Bearing of line AB = ?

Bearing of line AB = ?

360 42’B = D

C

B

A

Bearing of line BC = ?

2260 31’D =

Contd…


27


For the figure shown, compute the following. The deflection angle at B The bearing of CD The north azimuth of DE The interior angle at E The interior angle at F

CN 410 07’E

790 16’A

B

D

EF

S55 0 26’E

S120 47’E

S860 48’W

N120 58’W

Contd…


28


CN 410 07’E

790 16’A

B

D

EF

S55 0 26’E

S12 0 47’E

S860 48’W

N12

0 5

8’W

Contd…

Deflection Angle at B = 1800 - (410 07’+550 26’)

= 830 27’ R

Bearing of line CD = 1800 - (790 16’+550 26’)

= S450 18’ W

North Azimuth of line DE = 1800 - 120 47’

= 1670 13’

Interior Angle E = 1800 – (120 47’ + 860 48’)

= 800 25’

Interior Angle F = (120 58’ + 860 48’)

= 990 46’


29

5.4 Error in compass survey (Local 5.4 Error in compass survey (Local attraction & observational error) attraction & observational error)

Local attraction is the influence that prevents magnetic needle pointing to magnetic north pole

Unavoidable substance that affect are Magnetic ore Underground iron pipes High voltage transmission line Electric pole etc.

Influence caused by avoidable magnetic substance doesn’t come under local attraction such as instrument, watch wrist, key etc


30

5.4 Local attractions5.4 Local attractions

Let Station A be affected by local attraction

Observed bearing of AB = θ1

Computed angle B = 1800 + θ – ß would not be right.

B

CA

ß

θ1

θ


31


Detection of Local attraction By observing the both bearings of line (F.B. & B.B.) and noting

the difference (1800 in case of W.C.B. & equal magnitude in case of R.B.)

We confirm the local attraction only if the difference is not due to observational errors.

If detected, that has to be eliminated

Two methods of elimination First method Second method


32


First method Difference of B.B. & F.B. of each lines of traverse is checked to

not if they differ by correctly or not. The one having correct difference means that bearing

measured in those stations are free from local attraction Correction are accordingly applied to rest of station. If none of the lines have correct difference between F.B. &

B.B., the one with minimum error is balanced and repeat the similar procedure.

Diagram is good friend again to solve the numerical problem.

Pls. go through the numerical examples of your text book.


33


Second method Based on the fact that the interior angle measured on the

affected station is right. All the interior angles are measured Check of interior angle – sum of interior angles = (2n-4) right

angle, where n is number of traverse side Errors are distributed and bearing of lines are calculated with

the corrected angles from the lines with unaffected station.

Pls. go through the numerical examples of your text book.


34

5.5 Traverse, types, compass & 5.5 Traverse, types, compass & chain traversing chain traversing

Traverse A control survey that consists of series of established stations

tied together by angle and distance Angles measured by compass/transits/ theodolites Distances measured by tape/EDM/Stadia/Subtense bar

C

BA

ED

a1

e1

c1

b1

b2

c2


35

5.5 Traverse, types, compass & 5.5 Traverse, types, compass & chain traversing chain traversing

Use of traverse Locate details, topographic details Lay out engineering works

Types of Traverse Open Traverse Closed Traverse

C

B

A

ßΦ

E

D

γα

θ


36

5.5 Types of traverse5.5 Types of traverse

Open traverse Geometrically don’t close No geometric verification Measuring technique must be refined Use – route survey (road, irrigation, coast line etc..)

C

B

A

220 L

250 R


37

5.55.5

Close traverse Geometrically close (begins and close at same point)-loop traverse Start from the points of known position and ends to the point of

known position – may not geometrically close – connecting traverse Can be geometrically verified Use – boundary survey, lake survey, forest survey etc..

C

B

A

ßΦ

E

D

γα

θ

Types of traverseTypes of traverseContd…

CB

A

220 L

250 R D

Co-ordinate of A &D is already known


38

5.5 Methods of traversing5.5 Methods of traversing

Methods of traversing Chain traversing (Not chain surveying) Chain & compass traversing (Compass surveying) Transit tape traversing (Theodolite Surveying) Plane-table traversing (Plane Table Surveying)

C

B

A

D

b1b2

a2

a1

c1c2

C

B

A

b2

b1

c2

c1

Aa22 + Aa1

2 - a2a12

cosA2×Aa2×Aa1

=


39


Chain & compass traversing (Free or loose needle method) Bearing measured by compass &

distance measured by tape/chain Bearing is measured

independently at each station Not accurate as transit – tape

traversing

Contd…

AC

B

D

EF

length


40


Transit tape traversing Traversing can be done in many ways by transit or

theodolite By observing bearing By observing interior angle By observing exterior angle By observing deflection angle

Contd…


41

5.5 Methods of traversing5.5 Methods of traversingContd…

AC

B

D

EF

length

By observing bearing


42


By observing interior angle Always rotate the theodolite to

clockwise direction as the graduation of cirle increaes to clockwise

Progress of work in anticlockwise direction measures directly interior angle

Bearing of one line must be measured if the traverse is to plot by coordinate method

AE

F

D

CB

length


43


By observing exterior angle Progress of work in clockwise

direction measures directly exterior angle

Bearing of one line must be measured if the traverse is to plot by coordinate method A

E

F

D

CB

length


44


By observing deflection angle Angle made by survey line with prolongation of preceding line Should be recorded as right ( R ) or left ( L ) accordingly

CB

A

220 L

250 R D


45

5.5 Locating the details in 5.5 Locating the details in traversetraverse

By observing angle and distance from one station

By observing angles from two stations


46

5.5 Locating the details in 5.5 Locating the details in traversetraverse

By observing distance from one station and angle from one stationBy observing distances from two points on traverse line


47

5.5 Checks in traverse5.5 Checks in traverse

Checks in closed Traverse Errors in traverse is contributed by both angle and distance

measurement Checks are available for angle measurement but There is no check for distance measurement For precise survey, distance is measured twice, reverse

direction second time


48


Checks for angular error are available Interior angle, sum of interior angles = (2n-4) right angle,

where n is number of traverse side Exterior angle, sum of exterior angles = (2n+4) right angle,

where n is number of traverse side

C

B

A

ßΦ

E

D

γα

θ

Contd…

CB

A

ßΦ

ED

γ

α

θ


49


Deflection angle – algebric sum of the deflection angle should be 00 or 3600.

Bearing – The fore bearing of the last line should be equal to its back bearing ± 1800 measured at the initial station.

C

B

A

ßE

D

θ

ß should be = θ + 1800

Contd…

CB

A


50


Checks in open traverse No direct check of angular measurement is available Indirect checks

Measure the bearing of line AD from A and bearing of DA from D Take the bearing to prominent points P & Q from consecutive

station and check in plotting.

C

BA

ED

E

C

BA

ED

C

Q

P

D

Contd…


51

5.6 Field work and field book5.6 Field work and field book

Field work consists of following stepsSteps Reconnaissance Marking and Fixing survey station First Compass traversing then only detailing Bearing measurement & distance measurement

Bearing verification should be done if possible Details measurement

Offsetting Bearing and distance Bearings from two points Bearing from one points and distance from other point


52

5.6 Field work and field book5.6 Field work and field book

Field book Make a sketch of field

with all details and traverse in large size

Line Bearing Distance Remarks

AB

AE

BA

BC

CB

CD

DC

DE

ED

EA

C

B

ED

Ab1

b3b4

b2

w1

w2

Contd…

Line Bearing Distance Remarks

Bw1

Cw2

Db2

Db3

Eb4

Eb1


53

5.7 Computation & plotting 5.7 Computation & plotting a traverse a traverse

Methods of plotting a traverse Angle and distance method Coordinate method

LAT

ITU

DE

AX

IS

E (74.795, 49.239)D (26.879, 353.448)

C (138.080, 446.580)

B(295.351, 429.986)

A (300.000, 300.000)

DEPARTURE AXIS (0,0)


54


Angle and distance method Suitable for small survey Inferior quality in terms of accuracy of plotting Different methods under this

By protractor By the tangent of angle By the chord of the angle

Contd…


55


By protractor Ordinary protractor with minimum graduation 10’ or 15’

Contd…


56


By the tangent of angle Trignometrical method Use the property of right angle triangle, perpendicular

=base × tanθ

θb

P = b× tanθ

BA

D

Contd…

A

B

600

5cm 5cm

×tan60

0 cm

D


57


By the chord of the angle Geometrical method of laying off an angle

r BA

D

θA

450

5cm

(2×5×sin 450/2)cm

D

B

Contd…

rsinθ/2θ/2

θ/2

Chord r’ = 2rsinθ/2


58


Coordinate method Survey station are plotted by their co-ordinates. Very accurate method of plotting Closing error is balanced prior to plotting-Biggest

advantage

C

BA

D C’

B’A’

D’

E’

E

e’

C

BA

D

E

Contd…


59

5.7 Computation & plotting 5.7 Computation & plotting a traverse a traverseWhat is co-ordinates Latitude

Co-ordinate length parallel to meridian +ve for northing, -ve for southing Magnitude = length of line× cos(bearing angle)

Departure Co-ordinate length perpendicular to meridian +ve for easting, -ve for westing Magnitude = length of line× sin(bearing angle)

(+,+)

(-,-)

( +,-)

A

θ

B

L =

l×

cosθ

D = l×sinθ

I

(-, +)

IV

III II

l

Contd…


60


Consecutive co-ordinate Co-ordinate of points with reference to preceding point Equals to latitude or departure of line joining the preceding

point and point under consideration If length and bearing of line AB is l and θ, then consecutive

co-ordinates (latitude, departure) is given by Latitude co-ordinate of point B = l×cos θ Departure co-ordinate of point B = l×sin θ

A

θ

B

l

Contd…


61


Total co-ordinate Co-ordinate of points with reference to common origin Equals to algebric sum of latitudes or departures of lines between the

origin and the point The origin is chosen such that two reference axis pass through most

westerly If A is assumed to be origin, total co-ordinates (latitude, departure) of

point D is given by Latitude co-ordinate = (Latitude coordinate of A+ ∑latitude of AB, BC, CD) Departure co-ordinate = (Departure coordinate of A+ ∑Departure of AB,

BC, CD)

C

B

AD

Contd…


62


For a traverse to be closed Algebric sum of latitude and departure should be zero.

Dep. DA (+)

C

B

A

D

Lat

. D

A(+

)L

at.

AB

(+)Dep. AB (-)Dep. BC (-)

Dep. CDL

at.

CD

(+)

Lat

. B

C(-

)

Contd…


63


Real fact is that there is always error Both angle & distance Traverse never close Error of closure can be

computed mathematically

Closing Error (A’A) =√(∑Lat2+ ∑dep

2 )

Bearing of A’A = tan-1 ∑dep/∑lat

Dep. DA’C

B

A

D

A’

Lat

. D

A’

Lat

. A

BDep. ABDep. BC

Lat

. C

D

Lat

. B

C

Dep. CD

Contd…

∑lat

∑dep

A

A’

θ


64


Error of closure is used to compute the accuracy ratio Accuracy ratio = e/P, where P is perimeter of traverse This fraction is expressed so that numerator is 1 and denominator

is rounded to closest of 100 units. This ratio determines the permissible value of error.

Contd…

S.N. Types of traverse Permissible value of total linear error of closure

4

5

Minor theodolite traverse for detailing

Compass traverse

1 in 3,000

1 in 300 to 1 in 600


65


What to do if the accuracy ratio is unsatisfactory than that required Double check all computation Double check all field book entries Compute the bearing of error of closure Check any traverse leg with similar bearing (±50) Remeasure the sides of traverse beginning with a

course having a similar bearing to the error of closure

Contd…


66


Balancing the traverse (Traverse adjustment) Applying the correction to latitude and departure so

that algebric sum is zero

Methods Compass rule (Bowditch)

When both angle and distance are measured with same precision

Transit rule When angle are measured precisely than the length

Graphical method

Contd…


67


Bowditch ruleClat ∑L

∑l

= l× Cdep ∑D

∑l

= l×

Where Clat & Cdep are correction to latitude and departure

∑L = Algebric sum of latitude

∑D = Algebric sum of departure

l = length of traverse leg

∑l = Perimeter of traverse

Transit rule

Clat ∑L

LT

= L× Cdep ∑D

∑DT

= D×

Where Clat & Cdep are correction to latitude and departure

∑L = Algebric sum of latitude

∑D = Algebric sum of departure

L = Latitude of traverse leg

LT = Arithmetic sum of Latitude

Contd…


68


Graphical rule Used for rough survey Graphical version of

bowditch rule without numerical computation

Geometric closure should be satisfied before this.

C

BA

D C’

B’A’

D’

E’

E

e’

A C’B’ A’D’ E’

e’

aedcb

Contd…


69

5.7 Example of coordinate 5.7 Example of coordinate methodmethod

Plot the following compass traverse by coordinate method in scale of 1cm = 20 m.

Line Length (m) Bearing

AB 130.00 S 880 E

BC 158.00 S 060 E

CD 145.00 S 400 W

DE 308.00 N 810 W

EA 337.00 N 480 E

E

B

C

D

A


70


Step 1: calculate the latitude & departure coordinate length of survey line and value of closing error

Line Bearing Length (m) Latitude co ordinate Departure Coordinate

AB

BC

CD

DE

EA

S 880 E

S 060 E

S 400 W

N 810 W

N 480 E

130.00

158.00

145.00

308.00

337.00

-4.537

-157.134

-111.076

48.182

225.497

129.921

16.515

-93.204

-304.208

250.440

∑L= 0.932 ∑D = - 0.536

Closing Error (e) =√ (∑L2+ ∑D2 )

Closing Error (e) = 1.675 m

P = ∑l = 1078.00 m


71


Step 2: calculate the ratio of error of closure and total perimeter of traverse (Precision)Precision = e/P = 1.675/1078 = 1/643 which is okey with reference to permissible value (1 in 300 to 1 in 600)

Step 3: Calculate the correction for the latitude and departure by Bowditch’s method

Clat(AB) 0.932

1078

= 130×

= - 0.112

Cdep(AB) 0.536

1078

= 130×

= + 0.065


72


Step 4: Apply the correction worked out (balancing the traverse)

Line Latitude coordinate

Departure coordinate

Correction to Latitude

Correction to Departure

Corrected Latitude

co ordinate

Corrected Departure Coordinate

AB

BC

CD

DE

EA

-4.537

-157.134

-111.076

48.182

225.497

129.921

16.515

-93.204

-304.208

250.440

-0.112

-0.137

-0.125

-0.226

-0.291

+0.065

+0.079

+0.072

+0.153

+0.168

- 4.649

- 157.271

- 111.201

+ 47.916

+225.206

+129.986

+ 16.594

- 93.132

- 304.055

+ 250.608

∑L= 0 ∑D = 0


73


Step 5: Calculate the total coordinate of stations

Line Corrected Latitude

co ordinate

Corrected Departure Coordinate

Stations Total Latitude Coordinate

Total Departure Coordinate

AB

BC

CD

DE

EA

- 4.649

- 157.271

- 111.201

+ 47.916

+ 225.206

+129.986

+ 16.594

- 93.132

-304.055

+ 250.608

A

B

C

D

E

A

300.000

(assumed)

295.351

138.080

26.879

74.795

300.000 (CHECK)

300.000

(assumed)

429.986

446.580

353.448

49.239

300.00(CHECK)


74


E (74.795, 49.239)D (26.879, 353.448)

C (138.080, 446.580)

B(295.351, 429.986)

A (300.000, 300.000)

LAT

ITU

DE

AX

IS

DEPARTURE AXIS (0,0)


75

Degree of accuracy in Degree of accuracy in traversingtraversing

The angular error of closure in traverse is expressed as equal to C√N Where C varies from 15” to 1’ and N is the number of angle

measured

S.N. Types of traverse Angular error of closure

Total linear error of closure

1

2

3

4

5

First order traverse for horizontal control

Second order traverse for horizontal control

Third order traverse for survey of important boundaries

Minor theodolite traverse for detailing

Compass traverse

6”√N

15”√N

30”√N

1’N

15’√N

1 in 25,000

1 in 10,000

1 in 5,000

1 in 3,000

1 in 300 to 1 in 600


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5.7 Tutorial5.7 Tutorial

Plot the traverse by co-ordinate method, where observed data are as followsInterior anglesA = 1010 24’ 12” B = 1490 13’ 12” C = 800 58’ 42” D = 1160 19’ 12” E = 920 04’ 42”

Side lengthAB = 401.58’, BC = 382.20’, CD = 368.28’DE = 579.03’, EA = 350.10’Bearing of side AB = N 510 22’ 00” E (Allowable precision is 1/3000)

E

B C

DA


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unit 3: compass survey. 2 unit 5: compass traversing & traverse computation topics covered –...

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