Module-I SURVEYING-I [BTCVC304]

Definition, principles, classification, fields and office work, scales, conventional signs, survey instruments, their care and
adjustment, ranging and chaining, reciprocal ranging, setting perpendiculars, well-conditioned triangles, traversing, plotting ,
enlarging and reducing figures

1. Chainsurveying

2. ChainSurveying
•Chain(Tape)surveyingisthesimplestformofdetailsurveying.
•Inthismethodthelengthsoflinesmarkedonthefieldaremeasured,
whilethedetailsaremeasuredbyoffsetsfromtheseline.
•Chainsurveyingisthetypeofsurveyinginwhichonlylinear
measurementsaretakeninthefield.
•Thistypeofsurveyingisdoneforsurveyingofsmallextentto
describetheboundariesofplotsoflandandtolocatetheexisting
featureonthem.
•Itisthemethodofsurveyinginwhichtheareaisdividedinto
networkoftrianglesandthesidesofthevarioustrianglesare
measureddirectlyinthefieldwithachainoratapeandnoangular
measurementsaretaken.

3. Principles of ChainSurveying
•Theprincipleofchainsurveyingistodividetheareaintoanumber
oftriangles.
•Asatriangleistheonlysimpleplanegeometricalfigurewhichcan
beplottedfromthelengthofthethreesideseveniftheanglesare
notknown.
•Anetworkoftrianglesispreferredtochainsurveying.
•Triangulationistheprincipleofchainsurveying.
•Iftheareatobesurveyedistriangleinshapeandifthelengthsand
sequenceofitsthreesidesarerecorded,theplanoftheareacanbe
easilydrawn.

4. Principles of ChainSurveying

5. Principles of ChainSurveying

6. FIELD WORK & OFFICE WORK
Reconnaissance-
Thepreliminaryinspectionoftheareatobesurveyediscalledreconnaissance.
Markingstations-
Stationsaremarkedwithrangingrod,orwoodenpeg,drivinganailorspikesifhardsurface,orembeddingstone
withacrossmark
Referencesketches-
Aftermarkingthestationshouldbereferencedi.e.locatedbymeasurementcalledtiestakenfrom3permanent
pointswhichareeasilyidentifiedsuchascornerofbuilding.
Runningsurveyline-
Afterthepreliminarywork,chainingisstartedfrombaselineandcarriedthroughoutallthelineoftheframework
continuously.Sochainislaidandkeptlying,offsetaretakentolocatethenearbydetails.Makerangingwherever
necessary.

7. Suitability of chain surveying:
Ground surface is more or lesslevel.
Area issmall.
Small-scale map is required toprepare.
Formation of well conditioned triangle iseasy.
Chain surveying is not recommendedwhen:
Area is crowdedwith manydetails.
Area consists of too manyundulations.
Area is verylarge.
Formation of well conditioned triangle is not easy.

8. Well conditioned triangle, ill conditioned
triangle and ideal triangle.
•Atriangleissaidtobewellconditionedtrianglewhenno
angleinitisneitherlessthan30norgreaterthan120.
•Ifinatriangleanangleislessthan30orgreaterthan
120iscalledillconditionedtriangle.
•Anequilateraltrianglehavingeachangleof60isanideal
triangle.

9. Well conditioned triangle, ill conditioned
triangle and ideal triangle.

10. Ranging and Chaining

11. Ranging [Direct and Indirect]

12. Reciprocal Ranging

13. Setting Perpendiculars

14. Traversing

15. Plotting

16. SCALE
•Scaleisafixedratiothateverydistanceontheplanbearswithcorrespondingdistanceontheground.
•Onecentimetreontheplanrepresentssomewholenumberofthemetresontheground.
1cm=10m[Thistypeofscaleiscalledengineeringscale].
•1unitoflengthontheplanrepresentssomenumberofsameunitsoflengthontheground.
i.e.1/1000etc.
•Thisratioofmapdistancetothecorrespondinggrounddistanceindependentofunitsofmeasurementis
calledRepresentativeFactor(RF).
•Forexample,
1cm=50m
RF=1/(50×100)=1/5000
•Abovetwotypesofscalesarealsoknownasnumericalscales.