closed compass traverse

8/9/2019 closed compass traverse

1/6

CE 311L Fieldwork No. 15Closed Compass Traverse

1

Year & Section 3CE-A Date Performed October 20 2014

Group No. 3 Time Started 10:40 A. M.

Actual Site Benavides Park Time Finished 12:07 P. M.

Weather Condition Sunny Date Submitted November 3, 2014

Group Members Designation

Duran, Raphael V. Computer

Escueta, John Ezekiel Y. Instrument Man

Florencio, Ken Andrew A. Rodman

Guancia, Sigmond Ted M. Data Collector

Inocencio, John Angelo B. Rodman

Leyno, Iana Renza L. Writer

Lopez, Arvyn Rey N. Photographer

Manalo, Raymund Jericho B. Chief of Party

Fieldwork No. 15Closed Compass Traverse

I. Objective

To be able to gather data of a closed traverse and adjust this accordingly.

II. Introduction

A closed compass traverse consists of a series of lines of known length and magneticbearings which form a closed loop, or begin and end at points whose positions have been fixedby other surveys of higher precision.

III. Activities

Site: Benavides Park, University of Santo Tomas

Procedure:

1. Establish six points on the ground. Call these as stations A, B, C, D, E, and F,respectively;

2. Measure distance between stations A and B by taping;3. Set up and level the transit over point A (back station) and set the horizontal circle

and vernier to 0-0 reading;4. Release the magnetic compass needle and orient it along the reference meridian

(NorthSouth Line). Note that the end with the copper wire should point towards theSouth direction;

5. Sight point B (forward station) and observe the horizontal angle. Record this asforward bearing of line AB;

6. Transfer the transit over point B. Set up and level the transit and set the horizontalcircle and vernier to 0-0 reading;

7. Orient the magnetic compass along the reference meridian;8. Sight point A and observe the horizontal angle. Record this as the back bearing of

line AB;9. Repeat steps 2-8 for lines BC, CD, DE, EF, and FA, respectively; and

The Pontifical and Royal

University of Santo TomasThe Catholic University of the Philippines

Faculty of EngineeringDepartment of Civil Engineering

CE 311L: Surveying Fieldwork/LaboratoryLab 6, Ground Floor, Roque Ruao Bldg., Espaa

Boulevard, Sampaloc, Manila, Philippines 1008

(632)406-1611 loc. 8516


2/6


2

10. Choose the best line and adjust the open traverse.

IV. Formulas

Theoretical sum of interior angle = (n-2)180=720

Deficiency = Theoretical-Actual

Correction = Deficiency/6

FB-BB=0

Adjusted = (BB+FB)/2

V. Data and Results

15.1.1. Closed Compass Traverse

BackStation ForwardStation Line

Forward

Bearing000

Back

Bearing000

Adjusted Forward

Bearing000

Adjusted

Back Bearing000

A B AB S 11 27 E N 1127 W S 11 27 E N 1127 W

B C BC S 68 29 E N 6729 W S 67 59 E N 6759 W

C D CD N 5307 E S 54 08 W N 533730E S 53 37 30 W

D E DE N 2557 W S 23 51 E N 2452 30 W S 24 52 30 E

E F EF N 5110 W S 52 10 E N 5140 W S 51 40 E

F A FA S 727 W N 59 E S 618 W N 618 E

VI. Computations

BEST LINE:AB: 11 27 -11 27 = 0 0 BC: 68 29 -67 29 = 1 0CD: 53 7 -54 08 = -1 0DE: 25 54 -23 51 = 2 3EF: 51 10 52 10 = -1 FA: 7 27 -5 9 = 2 18

THEREFORE, LINE AB IS THE BEST LINE

FORLINE AB:

DE ADJUSTED = 11 27 -11 27 = 11 272

INTERIOR ANGLE:DEFICIENCY = 720 -(59 37 + 152 41 + 99 58 + 120 36 + 122 58 + 16324)

= 0 46 0


3/6


4/6


5/6


5


6/6


6

VIII. Sources of Errors

During an activity, the surveyors take note of the errors and itspossible sources. In thisfieldwork, the only possible error that can be found is an opening in the traverse as this fieldworkrequires the traverse to be closed. The error that was noticed hasdifference of 46 minutesbetween the theoretical and actual value of the total sum of interior angle. There are manypossible source that this error may have rooted. First error can be a simple human error incomputing as each line requires long input in computation, misreading numbers in a calculatorsare common. Second error can be a wrong sighting while finding for the azimuth for the back andfront reading. Getting a traverse to close means getting the angle right down to its seconds, soerrors here cannot be easily avoided.

IX. Conclusion and Remarks

After conducting the fieldwork, the surveyors were able to determine the bearing of 6 different

points for a closed traverse. The surveyors also concluded that to minimize the errors, the

angles must be aligned to 0 degrees horizontally.

X. References

La Putt, J.P. (2010). Elementary Surveying. Baguio, Philippines: Baguio Research and Publishing

Center.

closed compass traverse

Documents