工程项目计划系统PPT课件

.,1,工程项目计划系统PROJECTPLANNING,.,2,在总目标确定后，分析总目标能否实现计划同时又是目标的分解过程计划是实施的指南和实施控制的依据业主和项目的其他方面需要利用计划的信息,一、计划的作用,.,3,Onedistinguishingfeatureofprojectsisthateachistailoredtowardsomeuniqueend-itemorresult.Thatuniquenessimpliesthateveryprojectmustbedefinedanewandaschemecreatedtellingeveryoneinvolvedwhattodo.,.,4,Threethingsoccurintheplanningandcontrolprocess:(1)Duringtheconceptionanddefinitionphasesaplanispreparedspecifyingtheprojectrequirements,worktasks,responsibilities,schedules,andbudgets;(2)duringtheexecutionphasetheplaniscomparedtoactualprojectperformance,time,andcost;iftherearediscrepancies,(3)correctiveactionsaretakenandtherequirements,schedules,andbudgetsupdated.,.,5,PlanningstepsForstarters,theprojectteamneedstoanswerquestionsaboutwhathastobedone,howithastobedone,bywhom,inwhatorder,forhowmuch,andbywhen.Theformalizedwaytoanswerthesequestionsisthroughtheplanningprocess.,.,6,Projectobjectives,requirements,andscopeareset;Thespecificworkactivities,tasks,orjobstoachieveobjectivesarebrokendown,defined,andlisted;Aprojectorganizationiscreatedspecifyingthedepartments,subcontractors,andmanagersresponsibleforworkactivities,.,7,Ascheduleispreparedshowingthetimingofworkactivities,deadlines,andmilestones;Abudgetandresourceplanispreparedshowingtheamountandtimingofresourcesandexpendituresforworkactivitiesandrelateditems;Aforecastispreparedfortime,cost,andperformanceprojectionsforthecompletionoftheproject.,.,8,ToolsofProjectPlanningWorkbreakdownstructureandworkpackagesusedtodefinetheprojectworkandbreakitdownintospecifictasks.Responsibilitymatrixusedtodefineprojectorganization,keyindividuals,andtheirresponsibilities.Eventsandmilestonesusedtoidentifycriticalpointsandmajoroccurrencesontheprojectschedule.,.,9,GanttChartsusedtodisplaytheprojectmasterscheduleanddetailedtaskschedules.Networksclearlyshowinterdependenciesamongactivities.Criticalpathanalysiscriticalpathgivestheexpectedprojectduration.PERT/CPMprogramevaluationhowever,otherscanfallbehindwithoutdelayingtheproject.,.,22,网络计划技术是一种以网状图形表示计划或工程开展顺序的工作流程图。分单代号和双代号两种。,.,23,.,24,Thetwocommonmethodsforconstructingnetworkdiagramsarecalledactivity-on-node(AON)andactivity-on-arrow(AOA).Bothweredevelopedindependentlyduringthelate1950sAONaspartoftheCPMplanningmethod,andAOAinthePERTmethod.,.,25,Activity-on-arrowdiagramsIntheAOAmethod,theactivityisrepresentedasadirectedlinesegment(calledanarroworarc)betweentwonodes(orcircles).Thenodesrepresentthestartandfinisheventsfortheactivityinbetweenthem.(Thenumbersinsidethenodeshavenosignificancehere.Ingeneral,however,theyareusedtoidentifyeachevent.Thenumbersdonotneedtobeinanyparticularsequence,buteveryeventmusthaveauniquenumber.),.,26,.,27,predecessor,immediatepredecessor,successor,immediatesuccessor,sequentialactivities,parallelactivities,dummyactivities,.,28,AnAOAnetworkisconstructedbyfirstdrawinganodetorepresenttheoriginevent;thisrepresentsthestartofthefirstactivityintheproject.Thefinalorterminalnodeinthenetworkrepresentstheprojectcompletion.Everynetworkshouldhaveonlyoneorigineventandoneterminalevent.Allarrowsmustprogresstowardtheright-endofthenetworkandtherecanbenodoublingbackorloops.,.,29,DummyactivitiesAdummyactivityisusedtoillustrateprecedencerelationshipsinAOAnetworks.Itservesasa“connector”,however,andrepresentsneitherworknortime.Inpractice,dummyactivitiesshouldbeusedsparinglytokeepthenetworkassimpleaspossible.,.,30,Inconstructingnetworksbyhand,asaruleitiseasiesttostartbyputtingindummyactivitieswherevertheyseemnecessary,thenremovingthemfromplaceswheretheyarenotnecessary.The“overridingrule”isthatdummiescannotberemovedwheneveritresultsintwoormoreactivitiesthatrunbetweenthesametwostartandfinishnodes.,.,31,RedundantactivitiesAllactivitiesinaprojectexceptthefirstonehavepredecessors.Althoughonlytheimmediatepredecessorsneedbeknowntoconstructanetwork,itiseasytoaccidentallyspecifymorepredecessorsthannecessary.,.,32,.,33,ThecriticalpathThemajoruseofnetworksisforschedulingdetermininghowlongtheprojectwilltake(theexpectedprojectduration)andwheneachactivityshouldbescheduled.,.,34,Theexpectedprojectduration,Te,isdeterminedbyfindingthelongestpaththroughthenetwork.A“path”isanyroutecomprisedofoneormorearrows(activities)connectedinsequence.Thelongestpathfromtheoriginnodetotheterminalnodeiscalledthecriticalpath;thisgivestheexpectedprojectduration.,.,35,MultiplecriticalpathsCanaprojecthavemorethanonecriticalpath?Whynot?Inthecaseofmorethanonecriticalpath,adelayalonganyofthesepathswouldextendtheprojectduration.Suppose,youwantedtoreducetheprojectduration;youwouldthenhavetoshortenallthepaths.,.,36,EarlytimesESandEFESsandEFsarecomputedbytakinga“forwardpass”throughthenetwork.Whenanactivityhasseveralimmediatepredecessors,itsESisthelatestEFofallitsimmediatepredecessors;thisisthelatesttimewhenalltheimmediatepredecessorswillbecompletedand,hence,theearliesttimethenextactivitycanbestarted.,.,37,LatetimesLSandLFBeginbyassigningatargetcompletiondate,TS,totheterminalnode,wemakea“backwardpass”throughthenetwork.Wheneveranactivityisencounteredthathasmultiplepathsleadingbacktoit,itisthelongestbackwardpaththatbecomesthebasisforitsLF.ThisisthesameassayingthatitisthebackwardpathwiththesmallestLSthatprovidesthebasisforanactivitysLF.,.,38,TotalSlackTheESandLSforanactivityareoftennotthesame.ThedifferencebetweenLSandES(orLFandEF)isreferredtoasthetotalslacktime(orthe“slack”,orthe“float”)ofanactivity.Totalslack=LS-ES(=LF-EF),.,39,Totalslackforactivitiesonthecriticalpath(calledcriticalactivities)iszero;hence,delayinganyoftheseactivitieswilldelaytheproject.Activitiesnotonthecriticalpath(callednon-criticalactivities)canbedelayedbytheirslacktimewithoutdelayingtheprojectcompletion.,.,40,FreeSlackThetermfreeslackreferstotheamountoftimeanactivitycanbedelayedwithoutaffectingthestarttimesofanysuccessoractivities.ThefreeslackofanactivityisthedifferencebetweenEFfortheactivityandtheESofitsearliestsuccessor:Freeslack=ES(earliestsuccessor)-EF,.,41,ManagementschedulereserveTheTefirstcomputedfromthenetworkisusuallynotthedurationspecifiedasthecontractualcompletiontime.AmanagementschedulereserveisestablishedbysettingtherequiredtargettimeTsatsomeamountgreaterthanthetimeofthefinalscheduledeventTe.Generally,thegreatertheuncertaintyoftheproject,thelargertheschedulereserve.,.,42,CriticismofNetworkMethodsNetworkmethodshavebeencriticizedsincetheirinceptionbecausetheyincorporateassumptionsandyieldresultsthatsometimesareunrealisticorproseproblemstotheirusers.,.,43,Networkmethodsassumethataprojectcanbecompletelydefinedasasequenceofidentifiable,independentactivitieswithknownprecedencerelationships.Inmanyprojects,however,theworkcannotalwaysbeanticipated,andnotallactivitiescanbeclearlydefined.Rather,projects“evolve”astheyprogress.,.,44,Also,itisdifficulttodemarcateoneactivityfromthenext,andthepointofseparationismoreorlessarbitrary.Sometimessuccessorscanbestartedbeforepredecessorsarefinished,sothetwo“overlap”inthesequence.Althoughoverlapofactivitiesshortenstheestimatedprojectduration,thearbitrarinessofdemarcatingtheactivitiesincreasesitsvariation.,.,45,Precedencerelationshipsarenotalwaysfixed,however,andthestartofoneactivitymaybecontingentupontheoutcomeofanearlieronewhichmayhavetoberepeated.Theresultofatestactivity,forexample,maynecessitateredoinganalysisanddesign,whichinanetworkisa“loopback”toactivitiesthatprecededthetest.,.,46,网络计划的基本原理首先绘制工程施工网络图然后通过计算指出关键工作好关键线路接着选定目标不断改进计划,并对优化后的方案付诸实施最后在执行过程中进行有效的控制好监督,.,47,双代号网络图的绘制示例,.,48,2,A,3,B,4,C,5,D,6,E,F,G,8,H,1,7,.,49,关键工作和关键线路的确定若以网络终点节点的最早可能时间为网络总工期则关键线路上的各工作总时差皆为0若以合同工期为网络总工期,则以线路上总时差之和最小的线路为关键线路关键线路一般不止一条将关键线路的总时间缩短,关键线路可能变成非关键线路,.,50,各类时差的相互关系,Ti,E,Ti,L,Tj,E,Tj,L,.,51,PERTThreetimeestimatesPERTaddressuncertaintyinthedurationbyusingthreetimeestimatesoptimistic,mostlikelyandpessimistic.Theseestimatesthenareusedtocalculatethe“expectedtime”foranactivity.Therangebetweentheestimatesprovidesameasureofvariability,whichpermitsstatisticalinferencestobemadeaboutthelikelihoodofprojecteventshappeningatparticulartimes.,.,52,Theoptimistictimeisaminimumtimeactivitycouldtakethesituationwhereeverythinggoeswell;themostlikelytimeisthenormaltimetocompletethejob;thepessimistictimeisthemaximumtimeanactivitycouldtakethesituationwherebadluckisencounteredateverystep.Thepessimistictimeincludeslikelyinternalproblemsbutnotenvironmentalsnags.,.,53,ThethreeestimatesarerelatedintheformofBetaprobabilitydistributionwithparametersaandbattheendpoints,andmthemodal,ormostfrequently,value.ThePERToriginatorschosetheBetadistributionbecauseitisunimodal,hasfiniteendpoints,andisnotnecessarilysymmetricalpropertiesthatseemdesirableforadistributionofactivitytimes.,.,54,.,55,Basedonthisdistribution,themeanorexpectedtimete,andthevariance,V,ofeachactivityarecomputedusingthefollowingformulas:te=(a+4m+b)/6V=(b-a)/62ThelargerV,thelessreliablete,andthehigherthelikelihoodthattheactivitywillbecompletedmuchearlierormuchlaterthante.,.,56,ProbabilityoffinishingbyatargetcompletiondateBecausestatisticallytheexpectedtimeofasequenceofindependentactivitiesisthesumoftheirindividualexpectedtimes,theexpecteddurationoftheproject,Te,isthesumoftheexpectedactivitytimesalongthecriticalpath:Te=teWhereteareexpectedtimesoftheactivitiesonthecriticalpath.,.,57,Thevariationintheprojectdurationdistributioniscomputedasthesumofthevariancesoftheactivitydurationalongthecriticalpath:Vp=VWhereVarevariancesoftheactivitiesonthecriticalpath.,.,58,Asexamples,considertwoquestionsabouttheprojectshownbelow:1)whatistheprobabilityofcompletingtheprojectin27days?2)whatislatestlikelydatebywhichtheprojectwillbecompleted?,.,59,.,60,*Criticalpath*“Near”criticalpath,.,61,BothquestionscanbeansweredbydeterminingthenumberofstandarddeviationsthatseparateTsfromTe.Theformulaforthecalculationis:,.,62,Near-CriticalpathsPuttingtoomuchemphasisonthecriticalpathcanleadmanagerstoignoreotherpathsthatarenear-criticalorhavelargevariances,andwhichthemselvescouldeasilybecomecriticalandjeopardizetheproject.,.,63,Becauseallactivitiesinthenetworkmustbecompletedbeforetheprojectisfinished,theprobabilityofcompletingtheprojectwithin29daysisthesameastheprobabilityofcompletingallfivepathswithin29days.Thechanceofcompletingallpathswithin29daysistheproductoftheprobabilities(1.01.00.670.720.5),whichislessthan25percent.,.,64,SimulatingaPERTnetworkMonteCarlocomputersimulationisaprocedurethattakesintoaccounttheeffectsofnear-criticalpathsbecomingcritical.Timesforprojectactivitiesarerandomlyselectedfromprobabilitydistributionsandthecriticalpathiscomputedfromthesetimes.Theprocedureisrepeatedthousandsoftimestogenerateadistributionofprojectduration.TheproceduregivesanaverageprojectdurationandstandarddeviationthatismorerealisticthansimplePERTprobabilisticanalysis.,.,65,SimulationallowstheuseofavarietyofdistributionbesidesBeta,includingdistributionsbaseduponhistoricaldata.Thesegeneratedprojectdurationsaremorelikelytorepresenttherangeoftimetobeexpected.ThemethodalsoavoidssomelimitationsofPERTassumptions,suchasindependenceofactivitiesandnormalityoftheprojectdurationdistribution.,.,66,CriticismofPERTPERTassumesthatactivitytimescanbeaccuratelyestimatedandareindependent.Gettingthreeestimatesinsteadofoneaddstotheworkinvolved,andunlessthereisgoodhistoricaldata,allthreearestillguesses,whichisnotmuchofanimprovementoverasingle“best”guess.,.,67,Ifa“history”canbedevelopedofsimilaractivitiesfrompreviousprojects,activitytimeestimatescanbeimproved.Infact,therequirementforgoodhistoricaldatauponwhichtobaseestimatesmakesPERTmoreappropriateforprojectsthataresomewhat“repeatable”.Forthisreasonthethreetimeestimatesareusedprimarilyinconstructionandstandardizedengineeringprojects,butseldomelsewhere.,.,68,Theassumptionofactivitytimesindependencealsohasbeencriticized.Thedurationofanactivityisinfluencedwheneverresourcesoriginallyplannedforitaretransferredtootheractivitiesthatneedexpediting.TwoothercriticismsofPERTarethatitleadstooverlyoptimisticresultsandthattheBetadistributiongiveslargeerrorsinestimatingTe.,.,69,Criticalpathmethod(CPM)Time-costrelationshipThecriticalpathmethodassumesthattheestimatedcompletiontimeforaprojectcanbeshortenedbyapplyingadditionalresourceslabor,equipment,capitaltoparticularkeyactivities.Itassumesthatthetimetoperformanyprojectactivityisvariable,dependingontheamountofeffortorresourcesappliedtoit.,.,70,Unlessstatedotherwise,anygivenactivityisassumedtobeperformedatanormalworkpace.Associatedwiththispaceisthenormaltime,Tnhowlongtheactivitywilltakeundernormalworkconditions.Alsoassociatedwiththenormalpaceisthenormalcost,Cn,thepriceofdoingtheactivityinthenormaltime.,.,71,Usuallythenormalpaceisassumedtobethemostefficientandthusleastcostlypace.Extendingtheactivitybeyondthenormalpacewillnotproduceanyadditionalsavingsandmightwellincreasethecost.,.,72,Toreducethetimetocompletetheactivity,moreresourcesareappliedintheformofadditionalpersonnelandovertime.Asmoreresourcesareapplied,thedurationisshortened,butthecostrises.Whenthemaximumeffortisappliedsothattheactivitycanbecompletedintheshortestpossibletime,theactivityissaidtobecrashed.Thecrashconditionrepresentsnotonlytheshortestactivityduration,butthegreatestcostaswell.,.,73,Thetime-costofcompletinganactivityundernormalconditionsandcrashconditionstheoreticallydefinestwoextremepoints.Thelineconnectingthesepoints,calledthecostslope,representsthetime-costrelationship,ormarginaltrade-offofcost-timefortheactivity.Assumingasimplelinearrelationship,theformulaforthecostslopeis:Costslope=(Cc-Cn)/(Tc-Tn),.,74,Directcostofactivity,Cc,Cn,Tc,Tn,Crash,Normal,Slowerthannormal,Costslope,Durationofactivity,.,75,ReducingprojectdurationThecost-slopeconceptcanbeusedtodeterminethemostefficientwayofshorteningaproject.ShortestprojectdurationThestep-by-stepreductioneventuallyleadstotheshortestpossibleprojectduration.Anotherwayistocrashallactivitiesatonce.Thenstretchorincreaseanynon-criticalactivitybyacertainamountwithoutextendingtheproject.,.,76,TotalprojectcostThecostofconductingaprojectincludesdirectactivitycostsandindirectcostssuchasadministrativeandoverheadcharges.Usuallyindirectcostsareafunctionof,andincreaseproportionallyto,thedurationoftheproject.Inotherwords,indirectcosts,incontrasttodirectcosts,decreaseastheprojectdurationdecreases.,.,77,Projectcost,Total=direct+indirect,Directcost,Optimumduration,Projectduration,Indirectcost,.,78,Inadditiontodirectandindirectcosts,anothercostthatinfluencestotalprojectcostisanycontractualincentivesuchasapenaltychargeorabonuspayment.Apenaltychargeisalatefeeimposedonthecontractorfornotcompletingafacilityorproductontime.Abonuspaymentisarewardacashinducementforcompletingtheprojectearly.,.,79,Projectcost,Total,Penalty,Projectduration,Total&incentive,0,0,Bonus,Incentives,Contractagreement,.,80,五、成本计划1、积极的成本计划对不同方案的技术经济分析建设成本+运营成本全过程的成本计划管理项目赢利最大化资金的供应,.,81,总投资按目标分解,累计并对比目标,设计、工作量定义,分项估(预)算费用,2、成本计划过程,.,82,InputsScopedefinitionTimetoprepareQualityofcostdataEstimatorskill,Estimateaccuracy,Anestimatesaccuracydependsonthequalityofkeyinputs,.,83,3、计划成本的确定,固定资产投资,设备及工器具购置费,建安工程费,工程建设其他费用,预备费（基本预备费、涨价预备费）,建设期贷款利息,投调税,.,84,建筑安装工程费用的项目组成与计算,建筑安装工程费用项目组成,直接费,间接费,税金,利润,直接工程费,措施费,规费,企业管理费,.,85,前期策划阶段的估算参照过去同类工程信息，按照项目规模、生产能力或服务能力指标匡算按照国家或部门颁布的概算指标计算专家咨询法生产能力估算法,4、计划成本估算方法,.,86,项目设计和计划阶段的概预算使用定额资料，如概(预)算定额直接按部分工程，专项的供应或服务进行询价，以作为计划的依据采用已完工程的数据合同价,.,87,工程实施中的成本计划工作已完成或已支付成本追加成本(费用)剩余成本计划最终实际成本和结算价格