Unit 11ConstructionPlanningText1BasicConceptintheDevelopmentofConstructionPlans Constructionplanningisafundamentalandchallengingactivityinthemanagementandexecutionofconstructionprojects.Itinvolvesthechoiceoftechnology,thedefinitionofworktasks,theestimationoftherequiredresourcesanddurationsforindividualtasks,andtheidentificationofanyinteractionsamongthedifferentworktasks[1].Agoodconstructionplanisthebasisfordevelopingthebudgetandthescheduleforwork.Developingtheconstructionplanisacriticaltaskinthemanagementofconstruction,eveniftheplanisnotwrittenorotherwiseformallyrecorded.Inadditiontothesetechnicalaspectsofconstructionplanning,itmayalsobenecessarytomakeorganizationaldecisionsabouttherelationshipsbetweenprojectparticipantsandevenwhichorganizationstoincludeinaproject.Forexample,theextenttowhichsub-contractorswillbeusedonaprojectisoftendeterminedduringconstructionplanning. Indevelopingaconstructionplan,itiscommontoadoptaprimaryemphasisoneithercostcontroloronschedulecontrol.Someprojectsareprimarilydividedintoexpensecategorieswithassociatedcosts.TextInthesecases,constructionplanningiscostorexpenseoriented.Withinthecategoriesofexpenditure,adistinctionismadebetweencostsincurreddirectlyintheperformanceofanactivityandindirectlyfortheaccomplishmentoftheproject.Forexample,borrowingexpensesforprojectfinancingandoverheaditemsarecommonlytreatedasindirectcosts.Forotherprojects,schedulingofworkactivitiesovertimeiscriticalandisemphasizedintheplanningprocess.Inthiscase,theplannerinsuresthattheproperprecedenceamongactivitiesismaintainedandthatefficientschedulingoftheavailableresourcesprevails.Traditionalschedulingproceduresemphasizethemaintenanceoftaskprecedence(resultingincriticalpathschedulingprocedures)orefficientuseofresourcesovertime(resultinginjobshopschedulingprocedures).Finally,mostcomplexprojectsrequireconsiderationofbothcostandschedulingovertime,sothatplanning,monitoringandrecordkeepingmustconsiderbothdimensions.Inthesecases,theintegrationofscheduleandbudgetinformationisamajorconcern.Text2ChoicesofTechnologyandConstructionMethod Asinthedevelopmentofappropriatealternativesforfacilitydesign,choicesofappropriatetechnologyandmethodsforconstructionareoftenill-structuredyetcriticalingredientsinthesuccessoftheproject[2].Forexample,adecisionwhethertopumportotransportconcreteinbucketswilldirectlyaffectthecostanddurationoftasksinvolvedinbuildingconstruction.Adecisionbetweenthesetwoalternativesshouldconsidertherelativecosts,reliabilities,andavailabilityofequipmentforthetwotransportmethods.Unfortunately,theexactimplicationsofdifferentmethodsdependuponnumerousconsiderationsforwhichinformationmaybesketchyduringtheplanningphase,suchastheexperienceandexpertiseofworkersortheparticularundergroundconditionatasite[3]. Inselectingamongalternativemethodsandtechnologies,itmaybenecessarytoformulateanumberofconstructionplansbasedonalternativemethodsorassumptions.Oncethefullplanisavailable,thenthecost,timeandreliabilityimpactsofthealternativeapproachescanbereviewed.Thisexaminationofseveralalternativesisoftenmadeexplicitinbiddingcompetitionsinwhichseveralalternativedesignsmaybeproposedorvalueengineeringforalternativeconstructionmethodsmaybepermitted.TextInthiscase,potentialconstructorsmaywishtoprepareplansforeachalternativedesignusingthesuggestedconstructionmethodaswellastoprepareplansforalternativeconstructionmethodswhichwouldbeproposedaspartofthevalueengineeringprocess. Informingaconstructionplan,ausefulapproachistosimulatetheconstructionprocesseitherintheimaginationoftheplannerorwithaformalcomputerbasedsimulationtechnique.Byobservingtheresult,comparisonsamongdifferentplansorproblemswiththeexistingplancanbeidentified.Forexample,adecisiontouseaparticularpieceofequipmentforanoperationimmediatelyleadstothequestionofwhetherornotthereissufficientaccessspacefortheequipment.Threedimensionalgeometricmodelsinacomputeraideddesign(CAD)systemmaybehelpfulinsimulatingspacerequirementsforoperationsandforidentifyinganyinterference.Text3DefiningWorkTasks Atthesametimethatthechoiceoftechnologyandgeneralmethodareconsidered,aparallelstepintheplanningprocessistodefinethevariousworktasksthatmustbeaccomplished.Theseworktasksrepresentthenecessaryframeworktopermitschedulingofconstructionactivities,alongwithestimatingtheresourcesrequiredbytheindividualworktasks,andanynecessaryprecedenceorrequiredsequenceamongthetasks.Theschedulingproblemistodetermineanappropriatesetofactivitystarttime,resourceallocationsandcompletiontimesthatwillresultincompletionoftheprojectinatimelyandefficientfashion.Constructionplanningisthenecessaryfore-runnertoscheduling.Inthisplanning,definingworktasks,technologyandconstructionmethodistypicallydoneeithersimultaneouslyorinaseriesofiterations. Moreformally,anactivityisanysubdivisionofprojecttasks.Thesetofactivitiesdefinedforaprojectshouldbecomprehensiveorcompletelyexhaustivesothatallnecessaryworktasksareincludedinoneormoreactivities.Typically,eachdesignelementintheplannedfacilitywillhaveoneormoreassociatedprojectactivities.Executionofanactivityrequirestimeandresources,includingmanpowerandequipment.Thetimerequiredtoperformanactivityiscalledthedurationoftheactivity.Thebeginningandtheendofactivitiesaresignpostsormilestones,indicatingtheprogressoftheproject.Text Itisgenerallyadvantageoustointroduceanexplicithierarchyofworkactivitiesforthepurposeofsimplifyingthepresentationanddevelopmentofaschedule.Forexample,theinitialplanmightdefineasingleactivityassociatedwith"siteclearance."Later,thissingleactivitymightbesub-dividedinto"re-locatingutilities,""removingvegetation,""grading",etc.However,theseactivitiescouldcontinuetobeidentifiedassub-activitiesunderthegeneralactivityof"siteclearance."Thishierarchicalstructurealsofacilitatesthepreparationofsummarychartsandreportsinwhichdetailedoperationsarecombinedintoaggregateor"super"-activities. Inpractice,theproperlevelofdetailwilldependuponthesize,importanceanddifficultyoftheprojectaswellasthespecificschedulingandaccountingprocedureswhichareadopted[4].However,itisgenerallythecasethatmostschedulesarepreparedwithtoolittledetailthantoomuch.Itisimportanttokeepinmindthattaskdefinitionwillserveasthebasisforscheduling,forcommunicatingtheconstructionplanandforconstructionmonitoring.Completionoftaskswillalsooftenserveasabasisforprogresspaymentsfromtheowner.Thus,moredetailedtaskdefinitionscanbequiteuseful.Butmoredetailedtaskbreakdownsareonlyvaluabletotheextentthattheresourcesrequired,durationsandactivityrelationshipsarerealisticallyestimatedforeachactivity.Providingdetailedworktaskbreakdownsisnothelpfulwithoutacommensurateefforttoproviderealisticresourcerequirementestimates.Asmorepowerful,computer-basedschedulingandmonitoringproceduresareintroduced,theeaseofdefiningandmanipulatingtaskswillincrease,andthenumberofworktaskscanreasonablybeexpectedtoexpand.Text4DefiningPrecedenceRelationshipsamongActivities Onceworkactivitieshavebeendefined,therelationshipsamongtheactivitiescanbespecified.Precedencerelationsbetweenactivitiessignifythattheactivitiesmusttakeplaceinaparticularsequence.Numerousnaturalsequencesexistforconstructionactivitiesduetorequirementsforstructuralintegrity,regulations,andothertechnicalrequirements. Someactivitieshaveanecessarytechnicalorphysicalrelationshipthatcannotbesuperseded.Forexample,concretepourscannotproceedbeforeformworkandreinforcementareinplace.Someactivitieshaveanecessaryprecedencerelationshipoveracontinuousspaceratherthanasdiscreteworktaskrelationships.Some"precedencerelationships"arenottechnicallynecessarybutareimposedduetoimplicitdecisionswithintheconstructionplan.5EstimatingActivityDurations Inmostschedulingprocedures,eachworkactivityhasassociatedtimeduration.Thesedurationsareusedextensivelyinpreparingaschedule. Allformalschedulingproceduresrelyuponestimatesofthedurationsofthevariousprojectactivitiesaswellasthedefinitionsofthepredecessorrelationshipsamongtasks.Astraightforwardapproachtotheestimationofactivitydurationsistokeephistoricalrecordsofparticularactivitiesandrelyontheaveragedurationsfromthisexperienceinmakingnewdurationestimates.Text6EstimatingResourceRequirementsforWorkActivities Inadditiontoprecedencerelationshipsandtimedurations,resourcerequirementsareusuallyestimatedforeachactivity.Sincetheworkactivitiesdefinedforaprojectarecomprehensive,thetotalresourcesrequiredfortheprojectarethesumoftheresourcesrequiredforthevariousactivities.Bymakingresourcerequirementestimatesforeachactivity,therequirementsforparticularresourcesduringthecourseoftheprojectcanbeidentified.Potentialbottleneckscanthusbeidentified,andschedule,resourceallocationortechnologychangesmadetoavoidproblems. Manyformalschedulingprocedurescanincorporateconstraintsimposedbytheavailabilityofparticularresources.Anothertypeofresourceisspace. Theinitialprobleminestimatingresourcerequirementsistodecidetheextentandnumberofresourcesthatmightbedefined.Ataveryaggregatelevel,resourcescategoriesmightbelimitedtotheamountoflabor(measuredinman-hoursorindollars),theamountofmaterialsrequiredforanactivity,andthetotalcostoftheactivity.Atthisaggregatelevel,theresourceestimatesmaybeusefulforpurposesofprojectmonitoringandcashflowplanning.However,thisaggregatedefinitionofresourceusewouldnotrevealbottlenecksassociatedwithparticulartypesofequipmentorworkers.Text Moredetaileddefinitionsofrequiredresourceswouldincludethenumberandtypeofbothworkersandequipmentrequiredbyanactivityaswellastheamountandtypesofmaterials[5].Standardresourcerequirementsforparticularactivitiescanberecordedandadjustedforthespecialconditionsofparticularprojects.Asaresult,theresourcestypesrequiredforparticularactivitiesmayalreadybedefined.Relianceonhistoricalorstandardactivitydefinitionsofthistyperequiresastandardcodingsystemforactivities. Fromtheplanningperspective,theimportantdecisionsinestimatingresourcerequirementsaretodeterminethetypeoftechnologyandequipmenttoemployandthenumberofcrewstoallocatetoeachtask.Clearly,assigningadditionalcrewsmightresultinfastercompletionofaparticularactivity.However,additionalcrewsmightresultincongestionandcoordinationproblems,sothatworkproductivitymightdecline.Further,completingaparticularactivityearliermightnotresultinearliercompletionoftheentireproject.NewWordsandPhrasesDuration，n.持續(xù)時間，期間interaction，n.交互，相互作用schedule，n.進度，日程安排orient，v.以…為中心，面向incur，v.招致,發(fā)生prevail，v.優(yōu)先dimension，n.維度appropriate，adj.合適的，適合的，適宜的，適當?shù)膕imulate，v.模擬，仿真geometric，adj.幾何(學)的interference，n.干涉，干擾parallel，adj.平行的precedence，n.緊前工作iteration，n.迭代，重復exhaustive，adj.全面的,詳盡的hierarchy，n.層級presentation，n.表達vegetation，n.植被grading，n.坡度aggregate，n.總體commensurate，adj(在時間和空間上)相等的integrity，n.完整NewWordsandPhrasesreinforcement，n.鋼筋bottleneck，n.瓶頸crew，n.班組allocate，vi.分配,分派congestion，n.擁擠inthemanagementof，prep.---在---的管理bethebasisfor，prep.---依據(jù)是---evenif，adv.即使Inadditionto，prep.---除了---benecessaryto，adj.---是必要的---includein，vi.包括beusedon，vi.被用于dividedinto，vi.分為intheperformanceof，prep.---在--的性能iscriticalin，adj至關重要的overtime，prep.隨著時間的resultin，v.導致inaseries，n.一系列thesumof，adj.---的總和---theamountof，n.---的數(shù)量--forpurposesof，prep.---為了---Notes（1）Itinvolvesthechoiceoftechnology,thedefinitionofworktasks,theestimationoftherequiredresourcesanddurationsforindividualtasks,andtheidentificationofanyinteractionsamongthedifferentworktasks. 它涉及技術的選擇,工作任務的定義,所需資源的估計和個人任務的持續(xù)時間,以及不同工作任務之間相互作用的識別鑒定。（2）Asinthedevelopmentofappropriatealternativesforfacilitydesign,choicesofappropriatetechnologyandmethodsforconstructionareoftenill-structuredyetcriticalingredientsinthesuccessoftheproject. 在開發(fā)適當?shù)奶娲吩O施設計過程中,選擇合適的施工技術和方法通常是不良的結構，然而在項目的成功中起到關鍵作用。（3）Unfortunately,theexactimplicationsofdifferentmethodsdependuponnumerousconsiderationsforwhichinformationmaybesketchyduringtheplanningphase,suchastheexperienceandexpertiseofworkersortheparticularundergroundconditionatasite. 不幸的是，不同方法的確切含義取決于眾多因素，在計劃階段中信息可能是粗略的，例如有經(jīng)驗和專業(yè)知識的工人或者在一個站點特定的地下條件。Notes（4）Inpractice,theproperlevelofdetailwilldependuponthesize,importanceanddifficultyoftheprojectaswellasthespecificschedulingandaccountingprocedureswhichareadopted. 在實踐中,細節(jié)的適當水平取決于大小,重要性和項目的困難程度以及所采用的具體的調(diào)度和會計程序。（5）Moredetaileddefinitionsofrequiredresourceswouldincludethenumberandtypeofbothworkersandequipmentrequiredbyanactivityaswellastheamountandtypesofmaterials. 所需資源更多的詳細定義包括工人和設備的數(shù)量和類型兩個方面，需要通過一個活動以及材料的數(shù)量和類型。Exercise（TranslatethefollowingChineseintoEnglish,orE