CE121F Fieldwork 2

8/9/2019 CE121F Fieldwork 2

1/14

Mapua Institute of TechnologyIntramuros, Manila

School of Civil, Environmental and Geological Engineering

Surveying DepartmentCE121!"2

IE#D$%&' 2

#()I*G % ( SIM+#E C&-E ") T&(*SIT (*D T(+E .T/E I*C&EME*T(# C/%&DS (*D

DE#ECTI%* (*G#E MET/%D0

Sumitted y

+ascual, Ma3 *adine Stephanie D3

G&%+ *%3 4 Chief of +arty 5uitain,Geramie (3

Date of ield6or7 (ugust 18, 2918Date of Sumission (ugust 24, 2918

Sumitted to

Engr3 "ienvenido Cervantes

Data

ST(TI%* CE*T&(# DE#ECTI%*


2/14

I*C&EME*T(# C/%&D

I*C&EME*T(# (*G#E

(*G#E&%M "(C' T(*GE*T

%CC+IED %"SE&-ED

+C29:;?@A

+C29:;?@A

+C29:;?@A

+C29:;?@A

+C29:;?@A

+C29:; 9=>?@A

+C29:; 9;>?@A

+C29:; 9?@A

+C29:;?@A

+C29:; 19>?@A

+C29:; 11>?@A


3/14

+C29:; 12>?@A

+C29:; 1@>?@A

+C29:;?@A

+C29:; 1?>?@A

+C29:; 1=>?@A

+C29:; 1;>?@A

+C29:; 1?@A

+C29:;?@A

+C29:; 29>?@A

+C29:; 29>?4A

& B ?;234?


4/14

d2 B 9329=> C2 B 239=mStation of the -erte 21:992

Discussion

Same as the rst eld6or7, 6e have gathered our data giventhat the eld 6here 6e 6or7 in is also in the Intramuros $alls,6hich 6as still, good enough as the place to do this eld6or73

In this eld 6or7, it is aout laying out a simple curve ytheodolite and tape 6ith the use of incremental chord and

deection angle method3 $e did it properly ecause 6e follo6the proper steps in doing this eld6or73 irst 6e assemle theinstrument and then level it so the data that can e gathered 6ille accurate and correct and ecause 6e really had team 6or73

Theodolite 6as used to help us to determine the direction so 6ecan get an accurate angle3


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$e ma7e sure that the compass 6ill e directed to north3 Then 6e adFust the angle to 9> then move it to east 6ith an angleof ?9>3 Then the one 6ho 6as holding the range pole and the one

6ho 6as holding the tape measure 6ent to the place 6here thetelescope 6as heading so that 6e can mar7 the right place 6herethe verte 6as3 or the for6ard tangent, 6e did the same thingecept for the angle 6hich is S;E3 (fter determining the place6here +C and +T 6ere, 6e mar7 and measure the longest chordy measuring the distance of +C and +T3 Then 6e lay the curve ysimply follo6ing the incremental chord and deection anglemethod3

/onestly, at rst I got confused in doing this eld6or7ecause it is my rst time to encounter this 7ind of 6or7 and it isreally confusing3 "ut then, y the help of my professor, 6enished this eld6or7 properly3 I got confused in getting thedeection angle3 "ut then I discovered that is not that dicultecause you Fust have to add 2> to the rst deection angle3 (ndthe last deection angle should e less than or eHual to 2> that ifyou add all deection angle, it should e eHual to the intersectionangle 6hich in this eld6or7 is 82>3 (nd the rst incrementalchord can e computed and the rest 6ill e constant 6hich is 29ecept for the last incremental chord3 I 7ne6 that incrementalangle should e t6ice its central incremental angle3

In laying a simple curve, you can also Fust stay at your rststation, and Fust add the previous deection angle to the net oneand so are the incremental chord so that it 6ould not e that

hassle to the 6or7er3 "ecause it 6ould Fust e the same if you dothe station y station3 "ut I thin7, it 6ould still depend to the userecause for the one I have said, there is a possiility that you 6illforgot to add the previous measurement to the net one3 "ut, ityou 6ill e vigilant enough in 6hat you are doing, you 6ill notcommit any error3 or me, it 6ould too7 you a long time in leveling


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the instrument ecause in every station, you have to level theule of the instrument to ma7e sure that all the data 6ill ecorrect and accurate3

(lso, 6hat I have discovered, you can do this 6or7 easily ifyou are good in leveling an instrument and in moving theinstrument to the proper angle and also, if your group hasteam6or7 ecause you cannot do this easily in a short span oftime if you are alone3

/aving some s7ills in theodolite, gathering our data 6assome6hat easy for me since I listened to some of the tips thatEngr3 Cervantes have told us on ho6 to read the instrument, ho6to plot the station points onto the eld, and other related itemsthat 6ere needed to e done in order to succeed in the eld6or73

(s said in the discussion, a simple curve is an arc of a circle,6herein the point of intersection .+I0, is the point in 6hich the t6otangents, the for6ard and the ac7 tangent intersects it is alsomar7ed as -3 Then, the Intersection (ngle .I0 is otained through

sutracting the earing of the t6o tangents to 13 The radius isthen given, in 6hich it connects the center of the arc into the +Cand +T 6hich 6as to e eplained later3 The length of the curve.#C0 is the distance et6een the +C and +T and is measuredalong the curve3 +C is the point of curvature 6here the cureegins3 Then the +oint of Tangency .+T0 is 6here the simple curveends3


7/14

+hotos


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+lotting of the curve on the pavement ground using chal73

Sighting of the deection anglesusing the theodolite3

Computation of the data3


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&esearch $or7s

#()I*G % ( /%&IJ%*T(# C&-E

In this method, curves are sta7ed out y use of deectionangles turned at the point of curvature from the tangent to pointsalong the curve3 The curve is set out y driving pegs at regularinterval eHual to the length of the normal chord3 sually, the suKchords are provided at the eginning and end of the curve toadFust the actual length of the curve3 The method is ased on theassumption that there is no diLerence et6een length of the arcsand their corresponding chords of normal length or less3 The

underlying principle of this method is that the deection angle toany point on the circular curve is measured y the oneKhalf theangle sutended at the center of the circle y the arc from the+3C3 to that point3

#et points a, , c, d, e are to e identied in the eld tolayout a curve et6een T1 and T2 to change direction from thestraight alignment (- to -" as in igure @


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t6o suKchords have een provided one at the eginning, T1 andother, eT2 at the end of the curve3 The amount of deectionangles that are to e set from the tangent line at the +3C3 arecomputed efore setting out the points3 The steps for

computations are as follo6s

&eferring to igure @


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.*ote the units of measurement of chord and that of the radius of the curve should e same03

Similarly, tangential angles for chords of nominal length, say C,

And for last chord of length, say Cn

The deection angles for the diLerent points a, , c, etc3 can eotained from the tangential angles3 or the rst point a, thedeection angle ∆a is eHual to the tangential angle of the chord tothis point i3e3, δ13 Thus,

∆a = δ1.

The deection angle to the net point i3e3, is ∆ for 6hich thechord length is T1 3 Thus, the deection angle


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Thus, the deection angle for any point on the curve is thedeection angle up to previous point plus the tangential angle atthe previous point3

Conclusion

$e can say that our data gathered is accurate y our error inmeasuring the length of the chord, follo6ed the procedureproperly, and correct computation3


13/14

I can conclude that the data that 6e gathered on thiseld6or7 is accurate to say3 %ne of the reason is 6e have Fustonly less than one meter of error in the measurement of the chordcompared to the actual and the computed length of the chord3

(nother reason is that 6e follo6 the steps and 6e successfully didthe eld6or7 and lay do6n a simple curve in the Intramuros 6all6hich has the evident of the photos that I have presented to theproceeding part of this eld6or7 paper3 (nother reason to provethat the data is accurate is the computation3 In the computation,6e have follo6ed and doule chec7 the data and the given sothat 6e can get the missing data3 $e have also used the formulasand the eHuation given y the oo7 and y our +rof3 Cervantes in

doing the computation3

or 6hat 6e have done, I can say that it is accurate andprecise3 (s 6e all 7no6, errors are inevitale to us studentsecause 6e are Fust a rst timers and 6e need more eperiencesto do an almost perfect Fo3 (s 6hat our professor said, it is stillacceptale if 6e commit less than 13?O error ecause at least 6eachieve a good 6or73 "ut still, 6e cannot Fust say that 6eAre Fustrst timers so 6e cannot do something etter than anyone elseecause through passion and hard 6or7, you can do a etter Foeven you did not eperience that 6or7 efore3

In the process of the eld6or7, I 6ould say that ecause thegroup 7no6s the tactics in using the theodolite, 6e got the dataaccurately and eciently3 $e have also succeeded ecause 6ehave follo6ed the things needed to e done in 6hich have made

the 6or7 easier for us3

The oFectives of this eld6or7 6ere also achieved ecause6e are ale to lay the simple curve y deection angle and 6eare a6are of the parts of the curve 6e are 6or7ing on3


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&egarding the mastery of the s7ill in leveling, it is some6hateasy for us ecause 6e got our team6or7 and an ample amountof 7no6ledge in leveling3 Then, 6ith the usage of the theodolite,6e have succeeded eLectively as eplained a 6hile ago3

CE121F Fieldwork 2

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