Time Cost Trade Off

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relation of time and cost in the construction project

Transcript of Time Cost Trade Off

Chapter-2Construction Planning and scheduling2.1 ConstructionPlanning Introduction2.2Steps and stages of Planning2.3 Planningbycontractorandclient in diferent stages,2. Preparing schedule,2.! "i#e Cost trade of2.1 Construction Planning - IntroductionPlanning$Planningisaprocessby%hich#anagers setob&ecti'es,assessthefuture,andde'elop courses of actions to acco#plish thesePlanningispredeter#ination.Itistheprocessof setting goals and choosing the actions to achie'e goals.Planning con'eys the follo%ing three #eanings-a. It bridges the past e(periences and the proposed future actions for fa'orable functions,b. Precautionsareta)ento#ini#i*eundesirable efects orune(pected happenings and thereby eli#inatingconfusions,%asteandlossofti#e and increasing e+ciency and resources,Continued--c.It is a predeter#ining and specifying the factors, efects,forcesandrelationshipnecessaryto acco#plish the desired goals. "hepurposesofplanningcanbeholistically su##ari*ed in the follo%ing four purposes-1 "o eli#inate uncertainty of the future acti'ities,2 "oi#pro'ee+ciencyoftheoperations%ithout loss of eforts and confusion,3 "oobtainbetterunderstandingoftheob&ecti'es sothate'eryefortsaretargetedto%ards achie'ing the goals, and. "opro'idebasesfor#onitoringandcontrol during i#ple#entation of the plans. Continued--,oraoperationalplanthefollo%ingnineele#ents arenecessary,%ithoutanyoneofthe##a)es the plan inefecti'e-1.Objective2. program3. Schedule4. Budget5 Forecast6 Organiation!. "olic# $. "rocedure % and&. Standard.Continued---b&ecti'e$-b&ecti'esarethedestinationat%hichthe pro&ect has to be co#pleted. It #ay be cost, .uality and ti#econstraints."herefore,ifanob&ecti'eofaplanis to#eettheabo'econstraints,theacti'esta)eholders shall be a%are of the# and the plan ful/lls.Progra#$Progra#saretheactionstota)enby'arious in'ol'edpeopleinthepro&ect.Progra#s0ful/ll#ent leads to successful co#pletion of the pro&ect. "hese are 'arious acti'ities to be done.Schedule$"heprogra#s#ustbelaidontheti#escale. "hisscheduleindicates%hatacti'ityhastostartand %hat should be co#pleted at %hat ti#e.1udget$nothingisfree,so,budgetforeachacti'ityis necessaryfro#%hichlossorgaincanbeco#puted. 1udget plan is a #ust for any %or) to be perfor#ed.2.2Steps and stages of PlanningPlanning acti'ities re.uirethe infor#ation of a'ailability of resourceshu#anandnonhu#ans.2u#anresources #aybes)illedoruns)illed#anpo%er."heirtas)sof their e(celled %or) #ust be )no%n. Si#ilarly,nonhu#anresources#ayinclude#achines, #oney#aterialsetc."heirtas)or.uantityof%or)per unitti#eisnecessaryto)no%sothattotala#ountof the resources can be )no%n %hile planning."hetechnologyisanotherfactortobeconsidered. "echnologyafectsthee+ciencyofperfor#ance. "herefore,follo%ing#aybethestagesofplanningfor construction %or)-1. 3sti#ate of the %or),2. "as) or capacity of doing %or),3. Infor#ation of the locality a'ailable resources, and. ,inancing or 4llocating resources..Continued--3sti#ateofthe%or)s,%hichareobtainedfro# esti#ation of 'arious %or)s in'ol'ed fro# design and dra%ings. In it, the .uantity of diferent ite#s of %or), the .uality of the %or), the unit of #easure#ent and the rates per ite# of %or)s are ascertained."as)orthecapacityofdoing%or)byas)illed#anor #achinesisdeter#inedinthe5or#s-5epal."he capacity,thesituationandthepossibleheightare presu#ed. "hat cannot be changes and if changes are necessary,thatshouldbeappro'edfro#onesenior abo'e.4stheratesofite#sof%or)saredeter#ined consideringthea'ailabilityof'ariousresources,that shouldbeassu#edaccordingly%hileplanningfor successful i#ple#entation.Continued--,inancingisanotherfactorthatshouldbepaidattention %hile planning. 6sually /nancial planning is done prior to e(ecution.Itisnecessarysobecausehugea#ountofbudgetsare incurred%hilee(ecutingand#ostofthe%or)ersare dependent on the %ages they earned. 4t the sa#e ti#e, thebuildersaree(ecutingconstruction%or)sunder loans7ad'ancesfro#'ariousinstitutionsand%hene'er theysub#itthebillsofthe%or)done,usuallyitis necessaryto#a)epay#ent%ithina#onthorso, other%ise delay in the progress of %or) results."herefore, /nance planning #ust be done accurately. It %ill stateat%hatti#eorperiodofpro&ect,%hata#ountof #oneyforpay#entshallbere.uiredandaccordingly, the #anager or o%ner shall #a)e arrange#ents.2.3 Planning by contractor and client in diferent stages,Planning by Contractor$Contractor also )no%n as builder need to synchroni*e the a'ailablee'eryresourcessothatthedyna#is#ofthe %or) progress accelerates day after day till it co#pletes. 8a&orresourcesneedtobe#adea'ailableatsite, possible at the for# of 9I" :9ust in "i#e; to sa'e e(pense of storage and .uality degradation due to poor storage.4t the sa#e ti#e it needs to )eep good relation e'en %ith the local people at the site. In case of large pro&ects, the contractorneedsto#anageitslaborsfor schooling:training;,healthcareandotherrecreation centers for the people in'ol'ed in it. . ,abricationof?oors@Aindo%sandothersli)e truss arrange#ent,Continued--Aith the list of actions and the ti#e re.uired for deli'ery are%or)edoutfro#thecontractschedule,action Plans are based upon-a. resourcesa'ailable,-#anpo%er,#aterials, e.uip#entetca'ailableinthepro&ectthatcanbe e+ciently used,b. ti#eallocatedtoeachtas)s,-ti#ea'ailablefor eachtas)fro#the#asterplanareallocatedtoeach tas), but if the tas) is larger than the ti#e a'ailable, doubleortripleshiftorincreaseofresourcesare arranged,c. attain#ent:/nish; date of each tas)s- if the dates of attain#ent are nearer of the tas), it #ay need e(tra resources or e(tra ti#e or additional resources sothat perfor#ance can be speeded up.Continued--"hediferencebet%eentheplanningbyclientor contractoristhattheplansofclientsareusuallyof #ilestoneplan,in%hiche'entsareindicatesfor achie'e#ent,%hereastheplansofcontractorisof operational type in %hich acti'ity are gi'en priorities and accordingly e'ents are #et.3'entsaretheattain#ents%hereasacti'itiesare perfor#edtoattainthee'ents.8asterPlanand 8ilestonePlansareClients0plan,%hereasother typesofplansli)eacti'ity1archartsare contractor0s plan, in %hich start and /nish ti#es are distinctlyindicated.Incasefailuresoccurin attain#ent of start and or /nish of any acti'ity, e(tra resource #obili*ation is the only %ay to )eep up %ith the #aster schedule.Continued--Planningisapreparationofschedules.Schedulesare the laying out the acti'ities of a %or) o'er the ti#e a'ailable for co#pleting it. "he follo%ing can be the steps for preparing a schedule-1. 6sually the acti'ities of a %or) 7 &ob or pro&ects are bro)endo%nintos#alleracti'itiesthrougha%or) brea)do%nstructure:A1S;sothattheycanbe perfor#ed %ith a single s)ill. 2. "heyareprioriti*edinthe/rstperfor#ing acti'ities.3. 4 start date of the %or) is deter#ined. . ,ro# the start date, /rst prioriti*ed &obs are laid in thestartti#eandtherestaccordinglyinthe corresponding ti#es. !. Itcanbelaideitherinatabularfor#orinabar chart %ith distinct start and /nish date for each &ob. >. "he dates are usually the calendar dates.Continued--3'eryconstruction%or)sconsu#e'ariousresources li)e#aterials,#achines,ti#eand#anpo%erof diferents)ills,)indsandsi*es.4llofthose resources re.uired for a particular &ob cost a lot and also#aynotbea'ailableatthere.uiredti#e instantly,henceschedulingisnecessaryto#a)e a'ailable the resources. 2iring,borro%ingande#ployingscarceresourcesfor itsre.uire#entinthe%or)re.uiresschedulingso thatontheti#eofre.uire#ent,itcanbe#ade a'ailable at the site. 4lso,itgi'esaprecautionaryindicationofordering, inspectingand#o'ingtothesiteofthere.uired resourcesandesti#atesaccordinglycanbe#ade to ac.uire total budget. "hereare'arioustechni.uesofschedulingof acti'itiesofapro&ect,a#ongthe#1ar-Chart,CP8 and P3B" are so#e i#portant ones in practices Continued--Bar'(hart$1archart%as/rstde'elopedby2enryCantt, %ho%asanassociateofthe,atherofScienti/c 8anage#ent ,. A. "ailor in the /rst Aorld Aar. It %aslongti#etill1D!!thatthere%asno signi/cantde'elop#entinschedulingfro#the 1ar chart.1arChartisapictorialrepresentationofthe acti'itiesdra%ninathic)hori*ontalbar:line; against a calendar date or ti#e sale. It sho%s the startdateandenddateofproposedacti'ities dra%n across ti#e scales. "i#es scales are dra%n %ith'erticallinesdistributinghori*ontalti#e spaninati#eunitconsidered."heacti'itiesare obtained fro# Aor) 1rea)do%n structure.EAor)1rea)do%nstructureisasyste#aticand disciplinedapproachforbrea)ingdo%napro&ect into its #any co#ponents and sub-co#ponentsEContinued--Aor)1rea)do%nStructuregroupspro&ectacti'ities in hierarchical order for each stage of the pro&ect. "hePro&ect%or)isbro)endo%nintos#aller acti'ities,%hichare#easurable,#anageable andIntegratableintotalpac)ageatthetop.4n e(a#ple of BCC %or) bro)en do%n into acti'ities-"he%or)brea)do%nstructure:A1S;actsasa 'ehicleforbrea)ingdo%nthe%or)intos#aller ele#ents,thuspro'idingagreaterprobability thate'ery#a&orand#inoracti'ity%illbe accounted for. Si( le'els indentured structures as sho%n belo%$ BCC %or)Shuttering and centering to line and le'el8aterials supply ce#ent, aggregate, sand, steel, %ater.1ar cutting, bending, and binding and placingPreparing concrete, transporting, placing.co#pacting and curingContinued--=e'el ?escription123

!>)ierarchical order o* +BS1.,otal "rogram2."roject- .."3.Segment4.,as/- Bldg.5. 0ctivities6. .lements2."roject3.,as/- +1(4.Subtas/5. +or/ "ac/age6. 2evel o* .3ortPreparation of a 1ar Chart-,ollo%ing can be steps for preparing a bar chart-1rea)do%nthepro&ectintoanu#berofacti'ities thatre.uireseparate)no%ledgeands)illto perfor# and can be indi'idually perfor#ed,Consideringthea'ailableresourcesandti#e pro'isionforthepro&ect,allocateeachacti'itiesa reasonable ti#e for doing the#,5ote the start calendar date of the pro&ect and %or) out to get calendar dates for each of the acti'ities,Consider the calendar dates of each of the acti'ities for fa'orable cli#atic condition for perfor#ance,4lsonotethoseacti'ities%hichcanbestarted independently %ithout considering predecessor,4lsoconsiderresourceutili*inguptoareasonable le'el %ithout o'er or under loading the pro&ect %ith the#.Continued--F. Ariteeachacti'ityunderacti'itycolu#n syste#aticallyasperconstructionproceedsand dra%aboldlineunderti#escalecolu#nupto allocated ti#e pro'ision.G. "hebars,also)no%nasacti'itybar,canbedra%n parallel %ith diferent color to sho% perfor#ance.D. Pre'iouslyco#pletedacti'itiesandfollo%ing acti'itiestothe#canbelin)ed%ithalineand arro%head. 3(a#ple SN Activities Time allocation1 Materials (cement, sand, aggregates, steel) 2 weeks2 Shuttering and centering, 2 weeks3 Cutting, ending, !lacing and inding rein"orcements,3 weeks# Concrete mi$ing, trans!orting, !lacing and com!acting1 weekContinued--Starting ?ate$ ,algun 1, 2H!D 1SActivities Weeks Remarks1 2 3 4 5Materials (cement, sand, aggregates, steel) supply 211!"uttering and centering,311#utting, $ending, placing and $inding rein%&rcements,1#%11#&ncrete mi'ing, transp&rting, placing and c&mpacting 1122.!"i#e cost trade-ofAhen cost is reduced, certainly ti#e %ill to so#e e(tentincreaseand%henti#eisshortened, certainlycost%illincrease.1othoftheset%o resourcescannotbereducedtogether.4lso, theclient#ayso#eti#es%anttoshorten pro&ectti#e%ithout#atteringcostandat so#eti#einotherpro&ect,theo%ner#ay %anttoreducecost%hatsoe'ertheti#e%ill be ta)en up. 4ny pro&ect cost co#prises of the follo%ing t%o co#ponents-a. ?irect cost that decreases %ith ti#e increase, andb. Indirectcostthatincreases%iththeti#e increase."hetotalcostcur'ecanbeobtainedby co#biningthedirectcostcur'eandindirect cost cur'e as sho%n belo%. Continued--5or#al and Crash ti#e relationship of an acti'ity "heshapeofthecur'e0Bre'ealsthatthecost co#pletingtheacti'itycannotbereducedbelo% Job20e'enif#orethanJob10isallo%ed.4lso,the durationofacti'itycannotbereducedbelo%Jod10 e'enif%epreparedtospende(traa#ount :probably#orethanod2;to%ardsspeedy co#pletion of the pro&ect. (rash (ost5or#al CostCrash ti#e5or#al ti#e(ost"i#e0Ba2a1Ob2b1