Visayas State University College of Engineering DEPARTMENT OF CIVIL ENGINEERING Baybay, Leyte GEng 112 General Surveying II
Name: Joycelyn H. Uy "#, $%"$ Co&rse an! 'ear: BSCE(# $%"#
Date erforme!: December Date S&bmitte!: Jan&ary ),
LOCATION BY TREE!POINT RESECTION La"#ra$#ry E%er&i'e N#( ) I(
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*+ree(oint resection is a form of triang&lation. triang&lation. *+is met+o! of !etermining t+e location of an instr&ment by meas&ring t+e +ori-ontal angles beteen t+ree stations of /non osition an! location may be &se! in areas +ere e0isting control control oints cannot be occ&ie! or +en t+e or/ !oes not arrant t+e time an! cost of occ&ying eac+ station. *riang&lation *riang&lation of t+is tye s+o&l! be consi!ere! 1o&rt+(2r!er, alt+o&g+ *+ir!(2r!er acc&racy can be obtaine! if a strong triang&lar 3g&re is &se! an! t+e angles are acc&rately meas&re!. II(
O",e&$ive-'.+ ". *o !eter !etermin mine e analyti analytical cally ly t+e osition osition of an instr& instr&ment ment statio station n by meas&r meas&ring ing t+e +ori-o +ori-onta ntall angles angles beteen beteen t+ree stations of /non osition an! location.
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In'$ In'$ru ru/e /en$ n$' ' an* an* A&&e A&&e'' ''#r #rie ie'+ '+ Engine Engineer4s er4s *ransit ransit or *+eo!o *+eo!olit lite, e, 5ange 5ange oles, oles, H&bs H&bs an! 1lags or 6ar/ers.
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Pr#&e*ure+ ". 1rom t+e &n/non &n/non osition osition of oint 7instr&men 7instr&mentt station8, station8, t+e t+ree !esignate! control oints +ose ositions 79 ' Coor! Coor!ina inates8 tes8 are /non /non ere ere i!enti i!enti3e! 3e! on t+e gro&n gro&n!. !. *+ese stations ere calle! ;, B, an! C. *+ese stations ere
easily visible from oint by t+e &se of signals set & on t+e gro&n!. $. *+e instr&ment as set & an! levelle! at oint an! t+e +ori-ontal angles si7<8 an! lamb!a7=8 ere meas&re! in fo&r or more reetitions. #. ;fter t+e above observations are comlete!, t+e lengt+ an! !irection of lines ;B an! BC ere !etermine!, an! t+e angle at ;BC 7or >8. *+en t+e val&es of ?, 9, ', @, A, B, ;, an! C ere solve! to !etermine t+e coor!inates of oint . II(
Re'ul$' an* Di'&u''i#n+ Ta"le 1( C##r*ina$e' #0 A B an* C(
Station ; B C
Eastings ")%).% m $%%$.%" m $%%$." m $%%"." m
SAMPLE COMPTATIONS+
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Lengt+ of ;B an! BC Using !istance form&la: ! G ;B G ;B G $$.)# m BC G BC G . m ;-im&t+ of ;B an! BC, Using *an Bearing or ;-im&t+ of ;B G
;B G ;B G F2#4F.F# from N
Nort+ings $##. m $FF#. m $##.F" m $$."# m
BC G BC G "2F%4"". from N b8 ;ngle ;BC, I;BC G 7")% ( "2F%4"".8 F2#4F.F# G $#Fo4##.)# c8 2t+er reK&ire! &n/non elements in t+e 3g&re: ? G #% 7$#Fo4##.)# ( $24#% ( 2")4#%8 ? G $2#)4$."
9G
9G o 9 G $ %4".
' G $2#)4$." ( $o%4". ' G $ 2$4. I;B G ")% 72")4#% $o%4".8 I;B G 2#$4"%.F# IBC G ")% 7$24#% $2$4.8 IBC G "2$#4$#.F
; G
G $$.F$ m
C G
G $%).%% m
B G
G ""$."# m
Coor!inates of oint M Solve for latit&!e an! !eart&re of line CM
G "2F%4"". ( $2$4. G "o""4, C G ! G $%).%% Lat G !cos G $%).%%cos 7"o""48 G ")."" m De G !sin G $%).%%sin 7"o""48 G ".F) m Latit&!e is a!!e! to Nort+ing of station C, Deart&re is a!!e! to Easting of station C. Nort+ings of G $##.F" ")."" G $$."$" m Eastings of G $%%$." ".F) G $%%".") m DISCSSION+ ;, B, an! C are t+e main triang&lation stations +ose locations are /non. is t+e intersecte! oint +ose location is to be !etermine!. 2bservations are ma!e on from ;, B, an! C, an! t+e angle al+a, beta an! gamma are meas&re!. *+e lengt+s a an! b of ;B an! ;C, resectively, an! t+e angle B are /non as t+e coor!inates of ;, B, an! C are /non. *+e angle B can also com&te! from t+e /non coor!inates of ;,B, an! C as a c+ec/ on t+e observations. Ot is reK&ire! to !etermine t+e !istances ;, B an! C, so t+at can be lotte! by intersections.
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C#n&lu'i#n+ *+erefore, t+e osition of an instr&ment station as !etermine! by meas&ring t+e +ori-ontal angles beteen t+ree stations of /non osition an! location. *+e coor!inates of t+e station is 7$%%".") m, $$."$" m8.
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