工程造价外文文献

COSTANDTIMECONTROLOFCONSTRUCTIONPROJECTS:

INHIBITINGFACTORSANDMITIGATINGMEASURESINPRACTICE

YakubuAdisaOlawale,Ph.D.,MCIOBandMingSun,Ph.D.(Professor)

Abstract

Despitetheavailabilityofvariouscontroltechniquesandprojectcontrolsoftwaremanyconstructionprojectsstilldonotachievetheircostandtimeobjectives.Researchinthisareasofarhasmainlybeendevotedtoidentifyingcausesofcostandtimeoverruns.Thereislimitedresearchgearedatstudyingfactorsinhibitingtheabilityofpractitionerstoeffectivelycontroltheirprojects.Tofillthisgap,asurveywasconductedon250constructionprojectorganisationsintheUK,whichwasfollowedbyface-to-faceinterviewswithexperiencedpractitionersfrom15oftheseorganisations.Thecommonfactorsthatinhibitbothtimeandcostcontrolduringconstructionprojectswerefirstlyidentified.Subsequently90mitigatingmeasureshavebeendevelopedforthetopfiveleadinginhibitingfactors-designchanges,risks/uncertainties,inaccurateevaluationofprojecttime/duration,complexitiesandnon-performanceofsubcontractorswererecommended.Thesemitigatingmeasureswereclassifiedas:preventive,predictive,correctiveandorganisationalmeasures.Theycanbeusedasachecklistofgoodpracticeandhelpprojectmanagerstoimprovetheeffectivenessofcontroloftheirprojects.

Keyword:Costcontrol,interview,practice,projectcontrol,projectmanagement,

INTRODUCTION

Intheconstructionindustry,theaimofprojectcontrolistoensuretheprojectsfinishontime,withinbudgetandachievingotherprojectobjectives.Itisacomplextaskundertakenbyprojectmanagersinpractice,whichinvolvesconstantlymeasuringprogress;evaluatingplans;andtakingcorrectiveactionswhenrequired(Kerzner,2003).Duringthelastfewdecades,numerousprojectcontrolmethods,suchasGanttBarChart,ProgramEvaluationandReviewTechnique(PERT)andCriticalPathMethod(CPM),havebeendeveloped(Nicholas2001,Lester2000).Avarietyofsoftwarepackageshavebecomeavailabletosupporttheapplicationoftheseprojectcontrolmethods,forexampleMicrosoftProject,AstaPowerProject,Primavera,etc.Despitethewideuseofthesemethodsandsoftwarepackagesinpractice,manyconstructionprojectsstillsuffertimeandcostoverruns.Inrecentyears,therehavebeennumerousstudiesontheidentificationofinfluencingfactorsofprojecttimeandcostoverrunsworldwide.Mansfieldetal(1994)carriedoutaquestionnairesurveyamongst50contractor,consultantandclientorganisationsinNigeriaandfoundoutthatthemostimportantvariablescausingconstructiondelaysandcostoverrunsarepoorcontractmanagement,financingandpaymentofcompletedworks,changesinsiteconditions,shortageofmaterials,importedmaterialsandplantitems,designchanges,subcontractorsandnominatedsuppliers.Whilethetopvariablescausingonlycostoverrunswererevealedaspricefluctuation,inaccurateestimates,delays,additionalwork.Kamingetal(1997)identifiedfactorsinfluencingconstructiontimeandcostoverrunsonCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.high-risebuildingprojectsinIndonesiathroughaquestionnairesurveyadministeredon31projectmanagers.Atotalof11variables(designchanges,poorlabourproductivity,inadequateplanning,materialshortages,inaccuracyofmaterialestimate,skilledlabourshortageetc)wereidentifiedfortimeoverrunandseven(materialscostincreasedbyinflation,inaccuratequantitytake-off,lackofexperienceofprojectlocation,lackofexperienceofprojecttypeetc)forcostoverrun.KumaraswamyandChan(1998)conductedamoreextensivestudyinHongKongusing400questionnairesafterwhichfollowupinterviewswereheld.Thestudyrevealedthetoptencausesofconstructiondelaysfromthecontractors’pointofviewasdelaysindesigninformation,longwaitingtimeforapprovalofdrawings,poorsitemanagementandsupervision,mistakesanddiscrepanciesindesigndocuments,etc.SimilarsurveystudieswerereportedbyFrimpongetal(2003)inGhanaandbyAssafandAl-Hejji(2006)inSandiArabia.Inadditiontoquestionnairesurveys,otherresearchersadoptedacasestudyapproach.Al-Momani(2000)examined130publicprojectsinJordanandconcludedthatthemaincausesofdelaysincludechangesinitiatedbydesigners,clientrequirement,weather,siteconditions,latedeliveries,economicconditions,etc.Hsiehetal(2004)conductedastatisticalanalysisin90metropolitanpublicworkprojectsinTaiwanandidentifiedproblemsinplanninganddesignasmaincausesofchangeorders.Yogeswaranetal(1998)scrutinised67civilengineeringprojectsinHongKongandsuggestedthatatleasta15-20%timeoverrunwasduetoinclementweather.Basedonanalysisof46completedbuildingprojectsintheUK,Akinsolaetal(1997)identifiedandquantitativelyexaminedfactorsinfluencingthemagnitudeandfrequencyof

Citeas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.variationsinbuildingprojects.Thesefactorsinclude:clientcharacteristics,especiallylackofpriorexperienceandknowledgeofconstructionprojectorganizationandtheproductionprocesses;projectcharacteristics,suchastype,size,complexityanddurationoftheproject;andprojectorganisationfactors,suchas;designduration,percentageofdesigncompletedbeforetender,procurementandcontracttype,adequacyofinformationprovided,andnumberofsub-contractors.Whilealltheabovestudies,tovariousextents,helpedwiththebetterunderstandingoftheproblemsassociatedwithcostandtimeoverrunsinconstructionprojects,therearesomelimitations.(1)Someofthesestudiesareover10yearsold.Thereisaneedforamoreuptodateinvestigationtoreflectanydevelopmentinrecentyears.(2)MostofthestudieswerecarriedoutoutsidetheUK.Althoughconstructionprojectsworldwidesharesomecommoncharacteristics,therearealsosomecountryspecificconditions.Forexample,itishighlyunlikelythat“shortageofmaterials”and“importofmaterials”aremajorfactorsintheUK.Therefore,aUKbasedstudywillhelptoidentifyissuesmostrelevanttothecontemporarypracticeinthiscountry.(3)Someofthereviewedsurveyshadrelativelysmallsamplesizes,whichmayaffectthereliabilityoftheirresults.(4)Allthestudiesfocusedonidentifyingfactorsthathavethebiggestinfluenceonprojectcostsandtime.Theydidnotdiscussthedegreesofdifficultyincontrollingthesefactorsinpractice.Thereseemstobeanimplicitassumptionthatthemostimportantfactorsarealsothosemostdifficulttocontrol.Thisneedstobeexplicitlyvalidated.(5)Finally,mostexistingstudiesstoppedattheidentificationoftheinfluencingfactors,butdidnotprogressCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.ontofindingwaysofmitigatingtheidentifiedproblems.Theseobservationsunderlietherationaleforthisstudy.ItsaimistoidentifythemaininhibitingfactorsofprojectcontrolinpracticeintheUKandthentodevelopsomemitigatingmeasurestoassistprojectmanagersbettercontroltheirprojects.

RESEARCHMETHODS

Thisresearchadoptsacombinationofquantitativeandqualitativemethods.Itwasconductedintwostages.Thefirststagewasconductedusingaquantitativemethodthroughaquestionnairesurveyinabidtogenerateinformationfromalargesamplepopulation.Thesecondstageofthestudywasconductedusingthequalitativemethodusingsemi-structuredinterviews.Thereasonsforusingtheinterviewinadditiontothequestionnairesurveywere:totriangulatedataobtainedfromthequestionnairesurvey;toenhance,expandandcreatedepthtotheresultsofthequestionnairesurveybyinvestigatingandelaboratingonsomeoftheissueshighlighted;andtoexploretheexperiencesofthesamplepopulationinrelationtothetopicalissuesrevealedafteranalysisofthedataobtainedfromthequestionnairesurvey.

QuestionnaireSurvey

TheaimofthesurveyistoestablishthecurrentcommonpracticeoftimeandcostcontrolintheUKconstructionindustry,includingcontrolmethodsandsoftwareapplicationsbeingusedbypractitionersaswellasinhibitingfactors.ItstartedwithathoroughreviewofexistingstudiesthatrevealedalotofissuesonconstructionCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.projecttimeandcostoverruns,projectcontroltoolsandtechniquesandlatestthinkingandnewdevelopmentsinthefieldofconstructionprojectcontrol.Thisledtothedevelopmentofaquestionnairemadeupof22multiplechoicequestions.Thequestionnairewasdividedintothreesections:

Sectiononewasbackgroundinformationwhichwastargetedatobtaininginformationonthegeneralparticularsoftherespondentsandtheirorganisation,suchastheexperienceoftherespondnets,theirpositionwithintheorganisation,thetypeofprojectembarkedonbytheorganisationetc.

Thesecondsectionwasabouttimeoverrun,projectplanningandtimecontrolpracticesuchthefrequencyoftimeoverrunexperienced,thetechniquesusedforplanningandtimecontrol,thefactorsthathampersrespondentsfromeffectivelycontrollingtheirprojectsetc.

whilethethirdsectioncontainedsimilarquestionsbutspecifictocostcontrolpractices.Atotalof250questionnaireswereadministered;150tothetopconstructioncompaniesintheUKbycompanyturnoverandtheremaining100tothetopconstructionprojectconsultanciesinthecountrybythenumberofprofessionalstaffemployedandcompanyfeeearnings.ThislistwasobtainedfromtheBuildingmagazineannualleaguetables.Theleaguetablesdidnotcontaintheaddressesofthecompaniessoanonlinewebsearchwasconductedtofindtheiraddressesandcontactdetails.Telephonecallsweresubsequentlymadetothesecompaniestoconfirmtheaddressesandtofindoutthetypeofhierarchyandstructurethatexistswithintheorganisation.ThisenabledthequestionnairestobesenttotheappropriateCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.department.Tosupplementthis,thenameofaconstructiondirector,managerortheappropriatepersonnelwithahugeresponsibleforthemanagementofconstructionprojectsintheorganisationwasobtainedtoensurethatthequestionnaireswenttothecorrectaddressesandaddressedtotheappropriatepersonnel.Thisensuredaverygoodresponseas110questionnaires(44%responserate)werereturned.Tables1and2showtheprofileofthepractitionersthatrespondedtoquestionnaireonbehalfoftheircompanies.Nearly72%oftherespondentsthatcompletedthequestionnairesweredirectorsorseniormanagers,commercialmanagers.Aswouldbeexpectedfromtheirroles,theserespondentsalsohadsignificantyearsofexperienceintheconstructionindustry.Nearlyhalf(48%)ofrespondentshadmorethan25yearsofexperience.Thisshowedthattherewasgreatdepthintheexperiencepossessedbytherespondents.

DISCUSSIONS

Thisstudyapproachedtheinfluencingfactorsofprojectcontrolfromanewperspective.Aspreviouslymentionedalotofpreviousstudiesintheareaofprojectcontrolhavemainlybeenfocusedatcostandtimeoverrunsmostespeciallytheircauses.Theirfindingsareofteninfluencedbythespecificcontextofeachstudy.Manyresearcherscameupwithquitedifferentlistsoftopfactorsthathavemajorimpactoncostandtime.ThesurveyresultsofthisstudyreflectthecurrentviewsoftheleadingpractitionersintheUK.Anotheraspectthatdistinguishesthisstudyfrompreviousonesisthatthesurveyduringthefirststageofthestudyseekstoidentifythemainfactorsthathamperprojectmanagers’abilitytocontrolcostandtimenotjustthosethatmighthavethebiggestimpact.Itisinterestingtofindthatthetopfiveinhibitingfactorsareallprojectinternalelements.Thisisincontrasttopreviousstudieswheremanyexternalaspectsareoftencitedasmostimportantfactors,suchasinflation,materialshortage,unforeseengroundconditions,inclementclimate,etc.Citeas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.(Arditi,1985;Kamingetal,1997;Mansfieldetal,1994,KumaraswanyandChan,1998).Thepossibleexplanationforthisisthatalthoughexternalfactorsareusuallydifficulttocontrolorevenbeyondthecontrolofprojectmanagers,thefrequencyoftheiroccurrenceisgenerallow.Ontheotherhand,internalfactorsarepersistentand

requireconstantcontrolling.

Themitigatingmeasuresaredistilledfromin-depthinterviewswithveryexperiencedprojectmanagementpractitioners.Theyarenotsimplyselectedfromcurrentbestpractice.Theyreflectwhatshouldbedonetoimprovethecurrentprojectcontrolpractice.Forexamplein-depthinterviewsfoundthattherehasbeenageneraldeclineintheproductionofdetaileddesignforconstructionprojects;andthisisperceivedasoneofthegreatestcauseofdesignchanges,theforemostbottleneckduringtheprojectcontrolprocess.Itwasalsorevealedthatthereisoftenalackofdistinctionbetweenadesignchangeandadesigndevelopmentleadingtoargumentamongprojectpartners.In-depthinterviewsalsobroughttolightthefactclientscontributetotheproblemofprojectcostandtimecontrolbyimposingunachievableandunrealistictimescales.Theserevelationsledtothedevelopmentofanumberofmitigatingmeasures,someofthemeasuresdevelopedonthebackoftheseproblemsinclude;measures8(designingtheprojecttoagreatdetailattheoutsetwheneverpossible),1(cleardistinctionbetweenadesignchangeandadesign

developmentattheoutsetofaproject),37(educatingandadvisingclientonalternativeifanunachievable/unrealisticprojecttimescaleisstipulated),38(havingthecouragetorefuseunrealisticprojecttimescalebyclientsunwillingtoyieldtoCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.professionaladvise).Itwasalsorevealedthatquiteoften,thenon-performanceofsubcontractorsisnotnecessarilythefaultofsubcontractorsbutduetolackofeffectivemanagementbythemaincontractor.Themitigatingmeasuresthatstemmedfromthisinclude;66(properlydirectingthesubcontractortoensuretheyknowwhatisexpectedoftheminrelationtotheproject),68(puttingasysteminplaceforearlyidentificationofnon-performanceinsubcontractworks/packagesinordertonipitinthebudassoonaspossible)and69(utilisingperformancemeasurementse.g.S-curve,KPItomonitortheoutput/performanceofsubcontractorsontheirworkpackage).Thedevelopmentofthemitigatingmeasureswasalsobuiltontheexistingstudiesongoodbutoftengenericprojectmanagementpractices.Forexampleseveralpreviousstudiesrevealedthatthewoolyareaofdesignchangeanddesigndevelopmentisoneofthekeyreasonswhydesignchangeisconsideredabarriertoeffectivecostandtimecontrol.Tocombatthis,Kartametal(2000)recommendedthatenduserrequirementshouldbecloselycoordinatedintheearlyphaseoftheprojectandmoreattentionshouldbeplacedonmanagingthisrequirementduringtheconstruction

phase.Thisissimilartosomeofthemitigatingmeasuresidentifiedinthisstudybutthisstudyhasgonefurtherbymakingthemmorespecifictotheprojectcontrolprocess.Forexamplemeasures8,15and18intable12havebeenmadespecificformitigationofdesignchangesduringtheprojectcontrolprocess.Anothermitigatingmeasurefordesignchangeismeasure11(agreeingandputtinginplacechangemanagementprocedurebeforethecommencementofprojects,incorporatingthisCiteas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstruction

projects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.intothecontractifpossible).Thismeasurewasalsobuttressedbyanumberofstudiesindifferentways.ForexampleLeeetal(2005)identifiedprojectchange

managementasacriticalpracticethathasimportantimpactsonbothcostandscheduleperformanceorprojects.Lingetal(2009)inthestudyofkeyprojectmanagementpracticesaffectingprojectperformancefoundthatthemostsignificantpracticesthataresignificantlycorrelatedwithprojectperformancerelatetoscopemanagementandrecommendedthatemphasismustbegiventoscopemanagementinordertoachievesuperiorprojectperformance.SimilarlyZouandLee(2008)usedmultipleone-wayANOVAandlinearregressiontoinvestigatetheeffectivenessofchangemanagementpracticeselementsincontrollingprojectchangecostandfoundamongstothersthatusingchangemanagementpracticesistrulyhelpfulinloweringtheproportionofchangecostinprojectactualcost.Onanotherhand,Kogetal(1999)identifiedkeydeterminantsforconstructionscheduleperformanceanddiscoveredamongstothers,thathavingaconstructabilityprogrammeisakeydeterminanttoconstructionscheduleperformance.Aconstructabilityprogrammewasdescribedinthestudyastheapplicationofadisciplinedandsystematicoptimisationofconstruction-relatedknowledgeduringtheplanning,designprocurementandconstructionstagesbyknowledgeableexperiencedconstructionpersonnelwhoarepartoftheteam.Measures34,35,36and42intable14developedforthemitigationofinaccurateevaluationofprojecttimedurationarespecificpracticesthatwillgoalongwayatensuringthedevelopmentofaconstructabilityprogramme.Citeas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.Themitigatingmeasuresaretheresultofathreestagedresearchprocess.Itwillbewrongtoassumethatthesemeasuresareidentifiedfromonlyasmallnumberofinterviews.Infact,theinterviewisjustthelaststageofthedevelopmentofthesemeasuresinathreestageprocessinvolving,literaturereview,questionnairesurvey,intellectualthinkingandfinallytheinterviewswhichactedasawayofputtingsomepracticalityinthemitigatingmeasuresbydrawingfromthereallifeexperiencesofinterviewees.Itshouldalsobepointedoutthattheinterviewsdidnotaskpractitionersabouttheirexperienceofasingleprojectorasinglecompanybutdrewontheirexperiencesofmanyprojectstheyhaveworkedon.ThisapproachhasbeenadoptedbyrelatedstudiessuchasKartametal(2000),Gaoetal(2002)andSohailetal(2002).ForexampleSohailetal(2002)intheresearchaimedatdevelopingmonitoringindicatorsforurbanmicrocontractsbeganbystudyingarchivalrecordsofprojects,thenusedaquestionnairesurveytogeneratemoredata,conductedinterviewstogainmorein-depthunderstandingoftheofthesituationafterwhichthemonitoringindicatorswereeventuallydevelopedbyinferencesmadefromanalysisofinterviews,archivalrecordsandquestionnaires.Whilethesemitigatingmeasurescancontributetotheimprovementofprojectcontrolinpractice,therearealsosomelimitations.Thereisaneedforintegratingtheimplementationofthesemeasuresintoprojectcontrolmodels.Someofthesemeasuresoutlinewhatneedtobedone,butdonotaddresshowtheycanbeachieved.Issuesliketheseneedtobeinvestigatedinfutureresearch.Citeas:Olawale,Y.,andSunM.(2010).“Costandtimecontrolofconstructionprojects:Inhibitingfactorsandmitigatingmeasuresinpractice.”ConstructionManagementandEconomics,28(5),509–526.

CONCLUSIONS

Acombinationofquestionnairesurveyandin-depthinterviewshasbeenusedtoprovideusefulinformationonissuessurroundingprojectcontrolinpracticeintheUK.Issuessuchasthedegreeofapplicationofprojectcontrols,themostcommonlyusedtimeandcostcontroltechniques,supportingsoftwarepackages,frequencyoftimeandcostoverrun,theleadinginhibitingfactorstoeffectivecostandtimecontrol,thereasonsforthisandmeasuresthatcanbeusedfortheirmitigationwerebroughttolight.

ThetopfivefactorsinhibitingtimeandcostcontrolinconstructionpracticeintheUKwasrevealedasdesignchanges,risksanduncertainties;inaccurateevaluationofprojecttime/duration;complexityofworksand;non-performanceofsubcontractors.Designchangeisthesinglemostimportantfactorconsideredbypractitionersashinderingtheabilitytocontrolnotonlytimeofconstructionprojectsbutalsocost.Infact,itisfoundthatthereis