Multi-Project Management with a Multi-Skilled Workforce: A Quantitative Approach Aiming at Small Project Teams

319 Pages·2015·2.15 MB·English

by  Matthias Walter (auth.)

Produktion und Logistik
Herausgegeben von
C. Bierwirth, Halle, Deutschland
B. Fleischmann, Augsburg, Deutschland
M. Fleischmann, Mannheim, Deutschland
M. Grunow, München, Deutschland
H.-O. Günther, Bremen, Deutschland
S. Helber, Hannover, Deutschland
K. Inderfurth, Magdeburg, Deutschland
H. Kopfer, Bremen, Deutschland
H. Meyr, Stuttgart, Deutschland
K. Schimmelpfeng, Stuttgart, Deutschland
Th . S. Spengler, Braunschweig, Deutschland
H. Stadtler, Hamburg, Deutschland
H. Tempelmeier, Köln, Deutschland
G. Wäscher, Magdeburg, Deutschland
Diese Reihe dient der Veröff entlichung neuer Forschungsergebnisse auf den Gebie-
ten der Produktion und Logistik. Aufgenommen werden vor allem herausragende
quantitativ orientierte Dissertationen und Habilitationsschrift en. Die Publikatio-
nen vermitteln innovative Beiträge zur Lösung praktischer Anwendungsprobleme
der Produktion und Logistik unter Einsatz quantitativer Methoden und moderner
Informationstechnologie.
Herausgegeben von
Professor Dr. Christian Bierwirth Professor Dr. Herbert Kopfer
Universität Halle Universität Bremen
Professor Dr. Bernhard Fleischmann Professor Dr. Herbert Meyr
Universität Augsburg Universität Hohenheim
Professor Dr. Moritz Fleischmann Professor Dr. Katja Schimmelpfeng
Universität Mannheim Universität Hohenheim
Professor Dr. Martin Grunow Professor Dr. Th omas S. Spengler
Technische Universität München Technische Universität Braunschweig
Professor Dr. Hans-Otto Günther Professor Dr. Hartmut Stadtler
Technische Universität Berlin Universität Hamburg
Professor Dr. Stefan Helber Professor Dr. Horst Tempelmeier
Universität Hannover Universität Köln
Professor Dr. Karl Inderfurth Professor Dr. Gerhard Wäscher
Universität Magdeburg Universität Magdeburg
Kontakt
Professor Dr. Th omas S. Spengler
Technische Universität Braunschweig
Institut für Automobilwirtschaft
und Industrielle Produktion
Katharinenstraße 3
38106 Braunschweig
Matthias Walter
Multi-Project
Management with a
Multi-Skilled Workforce
A Quantitative Approach Aiming
at Small Project Teams
Foreword by Prof. Dr. Jürgen Zimmermann
Matthias Walter
Clausthal-Zellerfeld, Germany
Dissertation Clausthal University of Technology, 2014
DE-104
Produktion und Logistik
ISBN 978-3-658-08035-8 ISBN 978-3-658-08036-5 (eBook)
DOI 10.1007/978-3-658-08036-5
Library of Congress Control Number: 2014954235
Springer Gabler
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Foreword
Duetotheongoingglobalchangefromsellers’tobuyers’markets,theshareofindustrial
productionandservicesthatisprovidedintheformofprojectdeliverablescontinuesto
rise. EstimatessuggestthatcurrentannualbudgetsforprojectsamounttoU.S.$12trillion
or20%oftheworld’sgrossdomesticproduct. Hence,successfulprojectmanagementisof
salientimportanceforaneconomyasawholeandforeachsinglefirminvolvedinprojects.
Fromtheperspectiveofafirm,theselectionofprojectsandthestaffingofthechosen
projectsarecrucialforitssuccess. Inregardtoprojectexecution,afirm’sprosperityrelies
onanefficientuseofitsemployeesandtheirskills,onwell-performingprojectteams,on
smooth project execution, and on content employees. When employees have to work
in large teams, however, their individual performance may decline due to coordination
problemsandmotivationlosses.
Sofar,onlyafewoptimizationmodelsandmethodsexistthatofferdecisionsupport
for project selection and staffing and that consider special characteristics of human re-
sources. Theworkathand,whichmainlyaddressesthecompositionofanoptimalproject
portfolioandtheassignmentofworkerstosmallprojectteams, thustackleschallenging
problems,whoseresolutionharborsgreatbenefits. Forthefirsttime,thisworkdevisesa
hierarchicallyintegratedapproachthatsupportsdecisionmakerswhofaceselectionand
staffingproblemsgivenamulti-skilledworkforcewithheterogeneousskilllevels. Theap-
proach,whichwasdevelopedandalsocodedandthoroughlytestedbyMatthiasWalter,
comprisesthreestagesthatareassociatedwiththefollowingthreequestions:
(1) Whichistheoptimalprojectportfoliosubjecttoagivenworkforce?
(2) Howshouldtheavailableworkersbeassignedtotheselectedprojects?
(3) How can the workload of the employees be leveled assuming a matrix organization
whereworkrequirementsoriginatefromprojectsandfromdepartments?
Atthefirststage,portfolioselectionisconsidered. Here,afirmhastochooseasetof
projectsthateitherhavebeenrequestedbycustomersorhavebeenproposedwithinthe
firm. The selection is constrained by the capacity of non-consumable resources hold by
thefirm. Inhisthesis,MatthiasWalteroutlinesamodelthatexplicitlyaccountsforthe
capacities of human resources. Furthermore, he examines different skill configurations,
i.e., different cross-training strategies for workers. A new skill configuration is proposed
that enlarges the flexibility of a workforce. In addition, a refined flexibility measure is
devisedwhichshowsthatthenovelskillconfigurationissuperiortoestablishedchaining
configurations.
Thefocusofthethesisisonthesecondstagewherethestaffingproblemisdealtwith.
In this staffing problem, a team of workers must be composed for each project of the
firm. Eachworkermasterssomeskillsandeachprojectrequiresasubsetofallmastered
vi Foreword
skills. Theobjectiveistominimizeaverageprojectteamsizeand,hence,tominimizethe
average number of project assignments per worker. The objective prevents that project
teams suffer unduly from social loafing and that workers loose their focus. Since team
size has not been addressed before, the problem formulation and the proposed solution
methodsmakeavaluablecontributiontothefieldofmulti-projectmanagement.
Apostprocessingstepatthelaststageensuresthatdifferencesinworkingtimesamong
workers, which arise from the project assignments, are mitigated by allocating depart-
mentalworkload. Forthislevelingtask, alinearprogramisformulatedandsolvedbya
dedicatedpolynomial-timealgorithm.
The comprehensive performance analysis of the thesis demonstrates that the three-
stage approach is well suited even for large-scale planning problems. For instances that
featurealargenumberofprojectsandworkers,goodsolutionsaredeterminedinaccept-
abletime. Consequently,theapproachoffersagreatpotentialforpractitioners.
Altogether,theworkathandisaconvincingapplicationofoperationsresearchmeth-
odstothevitalfieldofprojectmanagementandprovidesanotableadvancementforthe
taskofformingprojectteams.
Clausthal-Zellerfeld,June2014 Prof.Dr.JürgenZimmermann
Preface
I wrote this thesis during my time at the Institute of Management and Economics at
ClausthalUniversityofTechnologyinClausthal-Zellerfeld. Inthistimebetween2008and
2014,itwasmyaimtodevisenewwaysthatsupportdecisionmakerswhofacechallenges
inmulti-projectmanagementandthatalsosupportthemembersoftheaffectedproject
teams. I tried to build these ways on a solid ground provided by operations research
methods. Myhopeisthatbothdecisionsmakersandprojectteammemberscanbenefit
fromtheideasandmethodsthatIhavedeveloped.
Completing the thesis would not have been possible without the support of many
people to whom I am very grateful. First of all, I would like to thank Prof. Dr. Jürgen
Zimmermann,whosparkedmyinterestinoperationsresearchwhenIattendedhislectures
duringmyundergraduatestudiesandwhogavemetheopportunitytoextensivelyexplore
the fascinating field of modeling and mathematical optimization as a research assistant
andPh.D.studentinhisdepartment. Asthesupervisorandchiefreviewerofmythesis,
hegrantedmecompletefreedomtobringforwardownideas,tofollowandabandonthem.
Hehadalwaystimetodiscusstheseideasandheprovidedvaluablehelp,especiallywhen
itbecamemathematicallytricky.
I am also very thankful to Prof. Dr. Christoph Schwindt, who kindly agreed to be
thesecondreviewer. Hesupportedmyworkmanytimesbysharinghisvastknowledge.
WhetherIaskedhimat9a.m.or9p.m.,healwaystookthetimetogivehelpfuladvice
andtopointtosuitableliterature.
The problems that I tackle in this thesis have a real background. This background
was brought to my attention by Roger Mähr and Martin Rudolph, managing directors
of Tiba Technologieberatung GmbH in Berlin. I would like to thank both of them for
thepleasantandtrustworthycooperation, fortheirwillingnesstosharetheirexperience
in project management gained in various industries and their knowledge of software for
projectmanagementtasks.
I owe special thanks to Dr. Christian Heimerl and Prof. Dr. Rainer Kolisch from
TechnischeUniversitätMünchenwhoprovidedvaluableinsightinefficientdatastructures
forthegeneralizednetworksimplexmethod. Myimplementationofthismethodprofited
considerablyfromtheinsight.
For an enjoyable working atmosphere, mutual support, enriching discussions, and
many joyful moments, I am very grateful to my colleagues within the Department for
Operations Research at the Institute of Management and Economics: I would like to
thank Sascha Effenberger, Carsten Ehrenberg, Alexander Franz, Dr. Thorsten Gather,
Dr.ClaasHemig,StefanKreter,PDDr.JuliaRieck,MarcoSchulze,andKatrinTormann.
Supportcamealsofromstudentassistantswithinthedepartmentandfromstudentswhose
seminarsorfinalyearprojectsdealtwithtopicsthatwererelatedtomythesis.
ItwasagreatpleasuretoworkattheInstituteofManagementandEconomics. Hence,
I thank all colleagues, especially former and current members of the “Mensa crew” for
viii Preface
relaxingandrefreshinglunchbreaks. Additionally,Iwouldliketothankallthosepeople
andinstitutionsofmyuniversitythatprovidedservicesvitalformylifeasaresearcher.
Theinstitutionsinclude,inparticular,thecanteen,thelibrary,andthecomputingcenter.
For proofreading and a critical review of a first draft and for many suggestions for
improvements Iam very muchindebted toCarsten Ehrenberg, AlexanderFranz, Stefan
Kreter,andDr.ThomasWalter.
Finally,Iwouldliketothankmyfamily,particularlymyparents,mybrotherThomas,
andmyuncleManfred. Withouttheirsupport,thisworkandmanyotheractivitiesduring
thelastyearswouldnothavebeenpossible.
Clausthal-Zellerfeld,June2014 MatthiasWalter
Contents
List of figures xi
List of tables xiii
List of algorithms xv
List of symbols xvii
1 Introduction 1
2 Background and motivation 7
2.1 Multi-projectmanagement . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Multi-skilledworkersandflexibilitydesign . . . . . . . . . . . . . . . . . . 17
2.3 Whysmallprojectteams? . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3 Problem definitions and basic notation 39
3.1 Settingoftheproblems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.2 Theprojectselectionproblem . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3 Theworkforceassignmentproblem . . . . . . . . . . . . . . . . . . . . . . 46
3.4 Theutilizationlevelingproblem . . . . . . . . . . . . . . . . . . . . . . . . 48
4 Optimization models and complexity analysis 53
4.1 Anintegratedapproachvs.ahierarchicalplanningapproach . . . . . . . . 53
4.2 Amodelfortheprojectselectionproblem . . . . . . . . . . . . . . . . . . 56
4.3 Modelsfortheworkforceassignmentproblemandtheirlimitations. . . . . 58
4.3.1 Twoalternativemodelsfortheworkforceassignmentproblem . . . 58
4.3.2 Limitations of the assignment models and potential remedies and
extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.4 Twoalternativemodelsfortheutilizationlevelingproblem . . . . . . . . . 68
4.5 Amonolithicmodelforallthreeproblems . . . . . . . . . . . . . . . . . . 71
4.6 Complexityanalysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.6.1 Basicconceptsofcomplexitytheory . . . . . . . . . . . . . . . . . . 74
4.6.2 Complexityoftheprojectselectionproblem . . . . . . . . . . . . . 79
4.6.3 Complexityoftheworkforceassignmentproblem . . . . . . . . . . 81
4.6.4 Complexityoftheutilizationlevelingproblem . . . . . . . . . . . . 86
4.6.5 Summaryofresults . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
5 Literature review 87
5.1 Workrelatedtotheprojectselectionproblem . . . . . . . . . . . . . . . . 87
5.2 Workrelatedtotheworkforceassignmentproblem. . . . . . . . . . . . . . 92