RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS · aids which are readily available locally...

RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS

Module-5APPROPRIATE SETTING OUT

TECHNIQUES

MINISTRY OF RURAL DEVELOPMENT

Ministry of Rural Development

RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS

Module-5Appropriate Setting Out Techniques

Contents: • Setting out tools

• Setting out techniques

• Quality control aids/templates

Learning Objective:At the end of this Module you are expected:

• Use various basic setting out aids

• Set out side drains

• Checkthatthesidedrainsareclearedforfreeflowofwater • Setoutmitredrainsandfindtheendofexcavation • Set out road cross-section of road

AcknowledgementThefollowingpublicationswerealsousedasreferencematerials: • Building Rural Roads, Bjorn Johannessen, International labour

Organization,ILORegionalOfficeforAsiaandthePacific,2008 • APractitioner’sGuidetoRuralRoadsImprovementandMaintenance,

InternationalLabourOrganizationandGovernmentofGhana,2014

This training module is produced through a collaborative effort between theInternational Labour Organization and the National Rural Road Development Agency under the technical assistance component of the World Bank supported Rural Roads Project-IIofPradhanMantriGramSadakYojanaProject(PMGSY).

5Foreword

PradhanMantriGramSadakYojana(PMGSY),waslaunchedinDecember,2000asa special interventionof theGovernmentof Indiawith thebroadobjective of ensuring sustainable poverty reduction. The scheme aimsto provide good quality all-weather single connectivity to every eligiblehabitation.Rural roads are a state subject under theConstitution and assucharethebasicresponsibilityofthestates.HoweverunderthePMGSY,theconstructionofgoodqualityandwell-engineeredroadsarefullyfundedbythecentralgovernment.Maintenanceoftheseroadsistheresponsibilityofthestates.Theyear2013sawthelaunchofPMGSY-IIwiththeobjectivesofconsolidatingtheexistingruralroadnetworkandupgradingexistingruralroadsthatprovideconnectivitytoruralgrowthcentres.PMGSY-IIenvisagessharing of construction costs between the Centre and the states withmaintenancecostscontinuingtobefundedfullybythestates.

Over the last14years, thePMGSYhascarvedoutaplace for itselfasaprogramme characterised by creation of good quality assets, effective management and technical proficiency by the National Rural Road DevelopmentAgency(NRRDA),alongwithcapablestateroadagencies.Forimplementation and operations, the involved agencies have been supported with detailed documentation in the form of programme guidelines, anoperations manual, standard bidding documents, specifications, a standard data book, a procurement and contracts management manual and the QualityAssuranceHandBookwithsupportfromtheIndianRoadsCongress.These documents have also contributed significantly towards effectiveimplementationofPMGSYandeven formainstreaminggoodpractices inotherruralroadsprogrammesbeingexecutedbythestatesfromtheirownresources.

An area of concern has been lack of regular maintenance as per the “ProgrammeGuidelines”.However,inrecentyears,therehasbeenincreasedawarenessandcommitmenttomaintenancebythestates.Thetemponeedstobesustainedandfurtheraccelerated.

Under the technical assistance component of the World Bank supported Rural Roads Project-II, the International Labour Organization (ILO), incollaborationwithNRRDAhaspreparedamanual“ManagingMaintenanceofRuralRoadsinIndia”.Thisinitiatedtheexecutionofmaintenanceworksand the development of these training modules for engineers and contractors associatedwithruralroadmaintenanceworks.TostrengthensuchactivitiesintheparticipatingstatesofRRP-II,aseriesoftrainingoftrainersworkshopswere arranged at national and state level based on the course materialdeveloped.

The training modules broadly cover the principles for maintenance management of rural roads, planning and execution of common maintenance interventions to ensure reliable transport services and safety to users and the local communities served by the rural roads, and arrangements for monitoringtheperformanceofcontractorsengagedforthetask.

I would like to acknowledge the support of all those associated with thedevelopment of these training modules, especially the ILO and its technical assistanceteam,Mr.HtunHlaing,Mr.BjornJohannessenandtheproject’sRural Roads Maintenance Engineers. I would also place on record thevaluablesuggestionsofmycolleaguesMs.ManjuRajpal,IAS,(exDirector–RC),Mr.R.Basavaraja,DirectorNRRDA,Mr.S.S.Bhatia,DeputyDirector,NRRDA,Mr.A.K.Sharma,ConsultantWorldBankandseniorengineersaswellassecretariesfromStateGovernmentsinbringingthedocumenttoitspresentshape.

Isincerelybelieve,thetrainingmoduleswouldbefoundusefulforthestatesin their efforts to secure adequate maintenance of all rural roads, not merely thePMGSY roadsand improvemaintenancepracticesso thatbenefitsofaccess continue to remain available for our rural people on a sustainable basis.

(RajeshBhushan,IAS)JS(RC)&DG,NRRDA

Ministry of Rural DevelopmentGovernmentofIndia

October,2015

5Introduction to Training Modules

The purpose of this training manual is to provide technical management staff and contractorswith appropriate guidelines for the effectivemanagementofroadmaintenanceworks.Thetrainingmodulesarebasedonthemanual“ManagingMaintenanceofRuralRoads in India”.Thesemodulesbroadlycover the principles for maintenance management of rural roads, planning and execution of common maintenance interventions to ensure reliable transport services and safety to users and the local communities served by the rural roads. The arrangements for monitoring the performance ofcontractorsengagedforthetaskarealsocoveredinthesemodules.

This manual is broken down into the following categories composed ofdifferent modules:

Module1: INTRODUCTION

Module2: TECHNICALCONSIDERATIONSANDIMPLEMENTATIONARRANGEMENTS

Module3: CONSTRUCTIONMEASUREMENTANDBASICCALCULATIONS

Module4: PLANNINGANDWORKORGANISATION

Module5: APPROPRIATESETTINGOUTTECHNIQUES

Module6: HANDTOOLS,EQUIPMENT&CONSTRUCTIONMATERIALS

Module7: ROUTINEMAINTENANCEWORKMETHODS

Module8: OCCUPATIONALHEALTH&SAFETY,ENVIRONMENTALISSUESANDDECENTWORK

Module9: COSTINGANDTENDERING

The trainer may decide to conduct a full course consisting of all the nine modules or may selectively conduct specific modules depending on the needsofthetargetgroup.

As a general advice the trainer should:

• Encourage active participation There is sometimes a tendency of the trainer to act like a teacher in

school and to read or lecture directly from the coursematerial. Thisbehaviourshouldbeavoided.Traineesrememberinformationbetterifthey participate actively in discussions and if there is a free exchange of viewsandofquestionsbetweeneveryoneparticipatinginthecourse.

INTRODUCTION TO TRAINING MODULES | i

• Guiding the discussion There are times during a discussionwhen everyonewants to speak

atthesametime.Whensuchsituationsarise,thetrainershouldinsistthatthegrouplistentoonepersonatthetime.Ifonespeakerhijacksthefloortoolong,thetrainerneedstointerrupt,pointingoutthatotherparticipantsmayalsowanttospeak.

• Listen attentively Equalattentionshouldbepaidtoeachspeaker.Listenattentivelyand

let the speaker understand that ideas and opinions expressed are both interestingandrelevant. It issometimesuseful totakeabriefnoteofparticipants’suggestionswhiletheyarespeaking,notingthemdownonaflipchartorblackboard.Asummaryofthesenotesmayproveusefulforlaterdiscussions.

• Emphasise important points Each time the participants make an important point or expresses an

interestingopinion,thetrainershoulddrawthegroup’sattentiontoitbyrepeatingtheideainsimpletermswhichareunderstoodbythemajorityofthetrainees.

• Preparing the sessions Whentraineesonlylistentoadescriptionofhowaparticularjobshould

be done, they are likely to forget what they heard. If however, theyactually carryout the task concerned, theywill rememberhow todoit. For this reason, every effort should bemade to include asmanypractical exercises and demonstrations as possible, be they carried out ontheworksiteorinthetrainingroom.Practicalsessionsshouldalwaysbecarefullyplannedinadvance.

• Recapping Adiscussion ismorethan justaconversation.Asubject isdiscussed

withanaiminmind. Itmayoccasionallybeworthwhilerecappingthetopic considered and recalling the aim of the discussion by intervening fromtimetotimetogiveabriefsummaryofthemainpointsdealtwithsofar.

• Questioning An important role of the trainer is to ensure that the atmosphere during

training is sufficiently relaxed to allow participants to feel at ease tospeak freely.Questionssetby the trainershouldnotbe regardedbythetraineesastests.Oftenthereisnostrict“rightorwrong”answertoaquestion,exceptformathematics.Questionsshouldsimplygiveyourtraineestheopportunitytoputforwardtheirindividualpointsofview.

ii | RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS

5Table of Contents

5. APPROPRIATE SETTING OUT TECHNIQUES 1

5.1 INSTRUMENTSUSEDFORSETTINGOUT 1 5.1.1 Tapemeasure 1 5.1.2 Rangingrodandprofileboard 1 5.1.3 Boningrods 2 5.1.4 Linelevelandbuildersline 2 5.1.5 Templates 4

5.2 BASICSETTING-OUTTECHNIQUES 5 5.2.1 Settingoutstraightsections 5 5.2.2 Settingoutrightangleusingtapemeasure 7 5.2.3 Settingoutrightangleusingstring 8 5.2.4 Setting-outa45°angle 10 5.2.5 Setting-out30°and60°angle 10 5.2.6 Transferringlevels 11 5.2.7 Establishingnewlevels 13 5.2.8 Measuringgradientusinglinelevel 13 5.2.9 Settingoutpredefinedgradientusinglinelevel 14 5.2.10 Adjustingverticallevelsinadrain 16 5.2.11 Settingoutoutfall(mitredrain) 18 5.2.12 Settingoutcrosssectionofroad 19

TABLE OF CONTENTS | iii

iv | RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS

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APPROPRIATE SETTING OUT TECHNIQUES | 1

5.1 INSTRUMENTS USED FOR SETTING OUTSetting out may be done by employing simplified instruments and aids or sophisticatedcapitalIntensiveSurveyinstrumentsuchasTheodolites,GPS,etc.

Howeverthissectionfocusesonthecorrectuseofsimpleinstrumentsandaidswhicharereadilyavailablelocallyandappropriateforaccuratelysetting-outruralroadworks.

Thefollowingaresomeofthemostcommonlyusedsettingoutinstrumentsusedinlabour-basedworks:• Tape measures • Boning rods • Templates

• Ranging rods • Profileboards • Line level and builders line

Someofthesettingouttools,instrumentandaidsareshownbelowandtheiruses.

5.1.1 Tape measureA great variety of tape measures exist.Themostcommonlengthoftape measure used for setting out is30mlong.Thetapesaremadeof steel or linen. Although theformer is stronger, the numbers/markingonthetapebecomesunreadableafteraperiodofuse.Itcanalsobeusedforsetting–outarightangle.Itshouldbenotedthatthezeropointisnotalwayslocatedatthesameplaceondifferenttapemeasures.

5.1.2 Ranging rod and profile boardRangingrodsaresticksusually2m longwithadiameterofapproximately2.5cm.Theyaremadeofvariousmaterials(metal,hardplastic,wood)andareusuallyprovidedwithapointedmetalend.Theyarepaintedalternatelyredandwhitewithblackmarkingatthe1-metrepoint.Itisusedforsettingoutstraightlinesandotheralignments.

Aprofileboardisdesignedinsuchawaythatitcanbeattachedtoarangingrod. It has a screwmechanism that enables the profile board to slide upanddownon the ranging rodandbe fixedatanydesiredpointsimplybytighteningthescrew.Along-lastingprofileboardisonemadefromthinsteel

Appropriate Setting Out Techniques

Figure 1: Various types of tape measures

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plate(40cmx10cm)weldedtoashortlengthofmetaltubingthatcanslideupanddownandcanbeclampedtothemetalrod.

Figure 2: Profile board and ranging rod

Itisusedforcontrollingverticalalignment,checkingorsettinggradients.

5.1.3 Boning rodsBoning rods are T-shaped and of a uniform height. They can easily bemanufactured by nailing a woodenlathof40cmlengthand10cmheighton to another lath of 130cm lengthand10cmwidthsothattheendresultlooks like a ‘T’. The horizontal lathshould be painted in clearly visible colours.Boningrodshavetobeusedinasetofthree.

The function of the boning rods is to check a vertical alignment by eye, in order to see if a section has an even gradient,whetheronlevelground,oronrisingorfallinggradients.

For example to check a section of mitre drain in flat country, where it is essential to verify that the drain invert falls at an even slope of 2%.

Itisusedforcontrollingverticalalignment.(e.g.invertlevelofsidedrains).

5.1.4 Line level and builders lineAlinelevelisasmallspiritlevelabout80mmto120mminlength.Ithasahookoneachend,whichisusedforhookingthelevelontoasmoothline.

Figure 3: Boning rods

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Thelevelisusedtogetherwithabuilder’sline, ranging rods (orprofileboards)anda tape measure. The line level requirestwo people to operate. The line level isusedfortakingthelevelsofpointsi.e.forcheckinghowtheheightofonepointvariesfromanother.

Alwayscheck: • Thatthebuilder’sline(string)issmoothorofnylon • Thatthebuilder’sline(string)istight • Thelinelevelisinthemiddlebetweenthetworangingrods • The accuracy of the level regularly

The accuracy of the line level can be checked as shown below (refer toFigure5): • Placetworangingrods20mapart • Fixalineonthe1m-markononerodandtransfertheleveltotheother

rod; mark this level

• Keeplineinplaceandturnthelevelround • Adjust lineagainandmarkthenewlevelandmeasurethedifference

betweenthetwolevels;ifdifferenceislessthan10cmthecorrectlevelisexactlyinthemiddleofthetwomarks,ifthedifferenceismorethan10cmthelevelshouldbechanged.

Figure 5: Checking accuracy of line level

5.1.5 TemplatesTemplates are used to control certain shapes of the road camber, ditches and canals.Mostcommontemplatesusedinlabour-basedroadworksareDitchingtemplate(usedforcontrol/checkingsidedrain/ditch),Slopingtemplate(usedforcontrolling/checkingthefore-slopeofsidedrainsasshowninFigure6),Camber board as shown in Figure 7 (for checking camber of gravel andearthroadswhichcomesinsets–un-compactedcamberboardusedwhen

Figure 4: Line level and builder’s line

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forming camber and compacted camber board for checking the compactedcamberandgravelling).Atemplate of the standard slope-ditch size can be used by the labourers to check continuously whether thecorrectshapeisdug.Templatesareusuallymadeofwoodorweldedmetaland tailor-made for each particular standard size of the drains, in accordance withthetechnicalspecifications.

Figure 7: Checking camber with camber-board

Templates are very useful control aids as any labour can see the exact size andshapeoftheworksheorheisrequiredtocarryout.

5.2 BASIC SETTING-OUT TECHNIQUES

5.2.1 Setting out straight sectionsFormostroadworksalignmentmustbeestablished,forexamplethecenterlineofa road, sidedrains,etc.Where thereareproperlydefinedexistingroads,theexistingroadwillshowthealignmentandmeasurementscanbetakenfromoffsetfromtheexistingroad.

Interpolation

The two end points ofthe straight line to be established are each markedwitharangingrod.The intermediate points can be found by sighting from one end rod to the other and moving a third rod until it is aligned with the twoendrods(seeFigure8).

Figure 6: Slopping template

Figure 8: Setting out straight by interpolation

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Extrapolation

Thesameprocedurecanbeusedtoextendastraight line(seeFigure9).Placetworangingrodsatacertaindistance,e.g.10m,alongthe lineyouwouldliketoestablish.Walkwiththethirdrodtothenextpointoftheline,e.g.another10mahead.Sightthefirsttworodsandshiftthethirdroduntilallthreerodsareinastraightline.Markthispointwithapegandrepeatthesameprocedureevery10muntilyouhavereachedtheendofyourstraightline.Checktheentirelineagain.

Figure 9: Setting out straight by extrapolation

5.2.2 Setting out right angle using tape measureItisoftennecessarytomeasureanangleof90degreesduringconstructionwork,forexample,whensettingoutaculvertandforconstructionoracrosssectionatrightanglestotheroadcenterline.

A triangle,whichhassidesof length3m,4mand5m,will alwayshavearightanglebetweenthe3-metresideandthe4-metreside.Wecanthereforeusethisknowledgetoconstructarightangleusingonlyatapemeasure.Tohelprememberthisusefulinformation,werefertothetriangleasa“3:4:5triangle”.

Procedure to construct a right angleusingatapetomakea3:4:5triangleisasfollows:

Step1: Therightangleisestablishedbymeasuringa trianglewithside lengths of 3m, 4m and5masillustratedinFigure10.

Step2: MeasurethelengthABof4malongthedefinedcenterline.Set pegs exactly at points A andB.Holdthezeropointofthe tape measure on the peg A.

Figure 10: Setting out a right angle by tape measure


Step3: Asecondpersonholds the8mmarkof the tapemeasureonpegB.Athirdpersonholdsthetapemeasureatthe5mmarkwhichwillleadtopointCwhenthetapemeasureispulledtight.

Thefollowingprocedurecanalsobeusedasanalternativemethodtosetouta3:4:5triangle.Arightanglecanalsobesetoutbyadifferentmethodwithonlyatapemeasure,usingthefactthatratiobetweenthethreesidesis3:4:5,asabove,(3m+4m+5m).Procedureasfollows:

Step1: Oneman hold the ‘zero’ point and the ‘12.00’mark on the tapetogether,

Step2: Asecondmanholdsarangingrodat thepointon thecenter linewheretherightangleisneeded.Heshouldrunthetapeoutsidetherangingrod,withthe‘3.00’markonthetapeheldfirmlyagainsttheranging rod,

Step3: The firstman (holding the ‘zero’andat ‘12.00’point) shouldnowbepositionedexactlyon thecenter line,with the tapeheld firmlyoutsidearangingrodandtautbetweenthetwomen,

Step4: Athirdmanholdsthetapefirmlyaroundanotherrangingrodatthe‘8.00’markandmoveuntilthetworemainingsidesofthetapearetaut.

Thiscreatesatriangleinthetape,withsidesof3m,4m,and5m.Theanglebetweenthecenterlineandthe5mside(betweenthe‘3.00’andthe‘8.00’marks)is90°orarightangle.

5.2.3 Setting out right angle using stringItispossible,withcare,toconstructarightanglewithonlyapieceofstringas equipment.The stringmust be between 5m and 10m long to give anaccurateresult.Figure11showsan illustrationofsettingoutarightangleusingapieceofstring.

Figure 11: Setting out a right angle by string

Proceduretoconstructarightangleusingapieceofstring:

Step1: Foldthestringinhalfandtieaknotexactlyinthemiddle,

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Step2: Alignthestringalongtheroadcenterline(oranylineofwhichtherightangle is required),with theknotat thepointwhere the rightangleisneeded(B),

Step3:Hammerinpegs(AandC)ateitherendofthestring,Step4: FrompegA,swinganarcofthefulllengthofthestring,Step5: FrompegC,swinganarcofthefulllengthofthestring,Step6: Marktheplace(D)wherethetwoarcscrosseachother.

5.2.4 Setting-out a 45° angleSometimesitisnecessarytosetouta45°anglesuchaswhensettingoutwing-walls.Thefollowingprocedureshowshowtosetouta45°angleusingstring:

Step1: Firstestablisharightangleasshownintheprevioussection.

Step2: Set out the same distanceon both of the two lines (L)starting from the intersection pointB,e.g.3m,andfixpegsAandC.

Step3: Span a string line betweenpoints A and C and measure this lengthA toC.Divide thelengthA toCby twoand setpeg D exactly in the middle of thislength.

Step4: EstablishthenewlineBtoDwithastringlineandextendbeyondpegDifnecessary.

5.2.5 Setting-out 30° and 60° angleSometimes it is necessary to set out a 30°or60°anglee.g.whensettingoutmitre drains. The following procedureshowshowtosetouta30°or60°angleusing string:

Step1: Firstestablisharightangleasshowninprevioussection.

Step2: Setoutthesamedistance(L)onbothofthetwolinesstartingfrom the intersection point B, e.g.3m,andfixpegsAandC.

Figure 12: Setting out 45° angle

Figure 13: Setting out 30° and 60°

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Step3: SpanastringlinebetweenpointsAandCandmeasurethislengthAtoC.DividethelengthAtoCbythreeandsetpegsD(for30°)afteronethirdofthelengthAtoC,orE(for60°)aftertwothirdsofthelengthAtoC.

Step4: EstablishthenewlinesBtoDorBtoEwithastringlineandextendbeyondpegDorEifnecessary.

5.2.6 Transferring levelsTransferringoflevelsisneededwhensettingoutcrosssections,settingoutdrains,mitredrainsandoutletdrains.

ThelevelatpointAonthegroundmaybetransferredtoanotherBasfollows:

Step1: FixtworangingrodsverticallyinthegroundatpointsAandB.Fixa level on the ranging rod at point A by making it or fixing a profile boardatadefinitedistanceabove theground,say1mabove theground.

Step2: FastenastringonthefixedlevelontherangingrodatAandadjustthe end of the stretched string at rod B until a line level hooked to ithasitsbubblecentred.ThestringisnowhorizontalandthepointwhereittouchestherodatBismarked.ThispointisatthesamelevelasthepointontherodA(1maboveground).

Figure 14: Transferring levels using line level

Step3: Measureout1mbelowthemarkedpointontherangingrodatBandmarkthispointtoo.ThispointwillbeatthesamelevelasthegroundlevelatpointA.NotethatifthegroundlevelatBishigherthanthegroundlevelatA,thetransferredlevelshallbebelowgroundlevel.IfthegroundlevelatAishigherthanB.thenthetransferredlevelshallfallabovegroundlevel.

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5.2.7 Establishing new levelsThefollowingprocedureinvolvessettingoutadefinedlevelaboveorbelowanotherknownlevel.

Step1: FixtworangingrodsverticallyinthegroundatpointsAandB.Fixa level on the ranging rod at point A by marking it or fixing a profile boardatadefinitedistanceabove theground,say1mabove theground.

Figure 15: Establishing new level using line level

Step2: Byusingastringandlinelevel,obtainandmarkpointatBatthesamelevelasthemarkontherodatA(1mabove).Thehorizontallevelisattainedwhenthespiritbubbleiscentred.

Step3: If the new level required at B, say y meters above the level atpointS,thenobtainthedifferenceof(1-y)meters.Measureoutthisdifference(1-y)metersbelowthemarkedpointontherangingrodatB.thispointwillbeymetersabovethegroundlevelatpointA.

Note that if the difference becomes negative, measure out above themarkedpointofrangingrodatpointB.

Step4: Similarly, if the new level required at B, say ymeters below thegroundlevelatpointA,then,addymetersto1m.Measureoutthissum(1+y)metersbelowthemarkedpointontherangingrodatB.thispointwillbeymetersbelowthegroundlevelatpointA.

5.2.8 Measuring gradient using line levelStep1: Fixrangingrodsverticallyatthetwoendpointsoftheslopefirmly

intotheground.

Step2: Tiethestringlineatthe1mmarkoftherangingrodatthehigherpointoftheslope.


Step3: Whilstholdingthestringlineatthelowerrangingrod,hookthelinelevelatthemiddlepointbetweenthetworangingrods.

Step4: Movethestringlineatthelowerpointrangingrodupordownuntilthelevelbubbleisexactlyinthemiddle.Markthislevelatthelowerranging rod, turn the line level around andmark the level again.Measure themiddle of the difference of the twomarks – this istheexacthorizontal level transferred from thehigher to the lowerrangingrod.

Step5: Measurethedifferencebetweenyourhorizontallevelmarkandthe1mmarkattherangingrod(=D).

Step6: Measuretheexactdistance(length)betweenthetworangingrods(=L).

Step7: Calculatethegradient(percentage)oftheslope.Thecalculationisasfollows:

DL

× 100 = Slope%

Figure 16: Finding the gradient of a slope

Note: Use centimetres for all measurements.

5.2.9 Setting out predefined gradient using line levelThefollowingarestepsinvolvedinsettingoutgradients:

Step1: Define level difference D by dividing L by 100% andmultiply bygivengradientGin%(e.g.3%asintheexamplebelow)

Step2: Fixthestringlinetothelowerrangingrodsothatthelineishorizontalandmarkthepointontheotherrangingrod.

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Step3: NowaddDto1meterandmeasurefromthelevelmarkdownwards.Youwillseethatinordertobeabletomeasurethisnewheight,youneedtodigasmallslotnexttotherangingrod.Digtheslotinsmallstepsuntilyoucanmeasuretheexactheight(D+1)meters.Thebottomofthisslotisnowattherequiredlevel.

Step4: Inordertotransferthegradientuniformlyyouhavetouseboningrodsorprofileboards.Setaboningrodateachendpoint,foreveryfewmetersdigasmallslot,setthethirdboningrod(traveller)atthebottom of the slot and deepen or raise the slot until all three boning rodsareinlinewithoneanother.

Figure 17: Setting out a pre-defined gradient

5.2.10 Adjusting vertical levels in a drainSometimewhenreshapingorclearingsidedrains,itisnecessarytocheckthatthewaterwillflowasplanned.Someoftheslopeoftheexistingdrainmaynotprovideanevensurfaceforthewatertoflowandthereforeithastobeadjusted.Themethodshownbelow,usingprofileboardstocheckandcontrolthedrainlevel,providesaneffectivewayofensuringthatwaterwillflowandtocorrectthewaterpondinginthesidedrainsandoutletdrainsofculverts.

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Step1: First,fixprofileboardsontherangingrodsalongthecentreofthedrainatafixedlevel,onemetreabovetheexistingdrainlevel.

Figure 18: Fixing ranging rods along the centre of side drains

Step2: Thensightalongtheprofileboards.Getanassistanttoadjustthelevel of each of the intermediate profile boards so that they are all on linewiththefirstandthelastprofile.Alltheprofileboardswillthenbeonemetreabovethecompletedlevelofthedrain.Theexcavationofthedrainshouldbe1mfromthetopoftheprofileboards.

Figure 19: Adjusting the profile boards to line of sight

Step3: Alternatively, a temporary boning rod ortraveller an easily be improvised by using the rangingrodupsidedownwiththeprofileboardfixed at 1m from the top of the ranging rod(Figure 20).The labourers should be able tohelp each other to correct the invert of the side drainbydiggingorfillingasnecessary.

To provide good guidance, it is useful to dig slotsatregularintervalsof4mto5malongthesight lines (Figure 21). With sufficient slots,the workers can start clearing the drains byremoving the soils between the slots. Finallyuse the traveller once again to control that the finished level is to the required slope and that therearenohighorlowspots.

Figure 20: Temporary traveller


Figure 21: Using the traveller check the drain invert level is excavated to desired depth

5.2.11 Setting out outfall (mitre drain)Therearethreestepsinvolvedinsettingoutamitredrain(outfall)whichare: i. Findingthemitredraininterval ii. Settingouttheangleformitredrain iii. Settingoutthemitredrainditchforzeroexcavation

Locations of all outlet and mitre drains should be checked before the final roadbedlevelisdecidedupon.Thisshouldnotcomeasanafterthoughtatanadvancedstageofconstruction.

Step1: Find the gradient of the intended side drain to be constructedusingmethodshowninearliersectioninthismodule.Basedonthegradient,refertomitredrainintervaltable.

Step2: Setouttheangleofthemitredrainatthepointwhereitshouldstartfromthesidedrainasshowninearliersectioninthismodule.

Step3: Follow the procedure outlined below to find out up to where themitre drain should be excavated:

Figure 22: Finding end point or length of outfall (mitre drain)

a. PlaceboningRod1inthecentreoftheditchattheturnoutpointforthemitredrainandRod2at10mor20mdownonthecentrelineofthemitredrain.

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b. AdjusttheprofileonRod1to1mabovethedraininvertlevelandsetoutthespecifiedgradienttotheprofileatRod2.(e.g.2%inthisexample).

c. SightovertheprofileswhileanassistantmovesatravellingrodonthegroundalongthedraincenterlineawayfromRod2.Thetravellerrodisarangingrodwithaprofileboardsetat1mabovetheendoftherodtouchingtheground.

a. Theendofthemitredrainisfoundwhereall the3profilesareflushwhensightingthroughthemfromoneend.

b. Measure the distance betweenRod 1 and the traveller. If thelengthofthemitredrainismorethan30m,thentrytoshortenthelengthbyincreasingthegradient.Ifthisisnotpossible,raisetheroadbedlevelorfindanotherlocationforthedrain.

5.2.12 Setting out cross section of roadAll cross-sections should be set out at right angles to the center-line of the road,asalreadydiscussedearlier.Thesettingoutoftheroadcross-sectioncan effectively be carried out using the same surveying tools and methods describedintheearlierSectionsinthisModule.

Procedure:

Step1: Usingthepreviouslyestablishedcenterline,setoutrangingrodsat10mintervalsalongthecenterlineforasectionof50to100metersindicatingtheprofileboardsat1mabovetheexpectedleveloftheshoulderbreakpoints(Figure23).

Figure 23: Set out profile boards along the center line ranging rods

Step2: At the start of the section,measure out the position of the roadshoulder break points and the outer end of the side drains from thecenterlineandmarkwithrangingrods(Figure24).Repeatthisexerciseattheotherendofthesection.

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Figure 24: Centre line, shoulder break point and outer end of side drains being marked by ranging rods

Step3: Oncethekeypositionsoftheroadcrosssectionhavebeensetoutatthe start and the end of a road section, sight in intermediate ranging rodsatevery10malong the roadshoulderbreakpointsandendofsidedrains.Placewoodenpegnexttoeachoftheintermediaterangingrods.

Step4: Fixprofileboardatthe1mheightoftheplannedverticalalignmentat the ranging rod at the center line and transfer the levels to the profileboardsattheouterrangingrods(seeFigure25).

Figure 25: Transfer level from the profile board at center line to the outer ranging rods

Step5: Transfertheselevelstotherangingrodsattheouterendofthesidedrains.Startwiththebeginningoftheroadsection.Usingastringand a line level, transfer the level of the profile board at the centre linetotheditchesonbothsidesoftheroad(Figure26).Oncethelevelsaresetoutwithprofileboards,markthelevelsonpegsnexttoeachrangingrod.

Figure 26: Transferring levels using line level and boning rod or profile board


Step6: Repeatthisprocedureforthesametworangingrodsat theotherend of the road section and for any intermediate profile along the center line thatwas liftedor lowered to reduceexcavationworks.Then,sightintheintermediatesidedrainlevels.

Step7: AscanbeenseeninFigure25above,theheightoftheprofileonthelowsideofthecenterlineismorethanonemeterwhentheroadispassingthroughterrainwithacross-slope.Ifthereisgoodnaturaldrainageonthelowersideoftheroad,itmaynotbenecessarytoinstalladrainon thisside instead letting thewater from the roadcamberflowoffthenaturalterrain.

Step8: Mark the levels for the center line on pegsplaced next to the ranging rods along the center line.Now,usethecenterlineprofileboardstoset out intermediate pegs, placed at every 5malong thecenter line.This iseasily carriedoutwithaonemeter tall traveller (Figure26).Rangingrodplacedupsidedownwiththebluntend at the bottom and profile board placed at the 1mheightfromthebluntendcanalsobeusedasatemporarytravellerasshowninFigure27.Markthesepegsatthepointwherethebottomofthetravellertouchesthepeg,whenlinedupwith the profiles. On all the center line pegs,markthelevelofthecrestofthecamber.

Step 9: Levels are usually indicated as three-digit numbers, showing the required cut or fill inmeters(e.g.+0.20meansthatafillof20cmisrequired).When the level is indicated,alwaysmeasurefromthetopofthepeg(Figure28).

Step10:Placethelevelsoftheshoulderbreakpointsalongtheroad.Forthis,itisonceagainusefultohavea traveller. Line up the traveller along the linebetween two sidedrain profiles, and thebottomof the travellerwill show the correct level of theshoulder.

Step11: Place pegs every 5m along the edge of theshoulder.Usingatraveller,markthesepegsatthepointwherethebottomofthetravellerendswhenitlinesupwiththeprofiles.

Step12:Locateandsetout themitredrainsasshown inprevioussection.Makesurethatthemitredrainsaresetoutbeforecommencingtheexcavationworksforthesidedrainsandcamber.

Figure 27: Temporary traveller using ranging rod and profile board

Figure 28: Survey peg with level written on it

5


Notes

This training module is produced through a collaborative effort between the International Labour Organization and the National Rural Road Development Agency under the technical assistance component of the World Bank supported Rural Roads Project-II of Pradhan Mantri Gram Sadak Yojana Project (PMGSY).

Designed and Printed By The Dezign Desq #9810196542.

INTERNATIONAL LABOUR ORGANIZATIONILO DWT for South Asia and Country Office for India

India Habitat CentreCore 4B, 3rd Floor, Lodhi Road

New Delhi–110 003, INDIA

NATIONAL RURAL ROADS DEVELOPMENT AGENCYMinistry of Rural Development, Government of India

5th Floor, 15-NBCC TowerBhikaji Cama Place

New Delhi–110 066, INDIA

RURAL ROAD MAINTENANCE TRAINING MODULES FOR CONTRACTORS · aids which are readily available locally...

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