Network Scheduling Techniques for Construction Project Management

Nonconvex Optimization and Its Applications

Volume 16

Managing Editors:

Panos Pardalos University of Florida, U.S.A.

Reiner Horst University of Trier, Germany

Advisory Board:

Ding-ZhuDu University of Minnesota, U.S.A.

C.A.Aoudas Princeton University, U.S.A.

G.lnfanger Stanford University, U.S.A.

J. Mockus Lithuanian Academy of Sciences, Lithuania

P.O. Panagiotopoulos Aristotle University, Greece

H.D. Sherali Virginia Polytechnic Institute and State University, U.S.A.

The titles published in this series are listed at the end of this volume.

Network Scheduling Techniques for Construction Project Management by

Mikl6s Hajdu Technical University o/Budapest Budapest. Hungary

SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

A C.I.P. Catalogue record for this book is available from the Library of Congress

ISBN 978-1-4419-4765-9 ISBN 978-1-4757-5951-8 (eBook) DOI 10.1007/978-1-4757-5951-8

Printed on acid-free paper

AlI Rights Reserved © 1997 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1997

No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permis sion from the copyright owner.

CONTENTS

PREFACE

ACKNOWLEDGEMENTS

CHAPTER 1 Introduction 1.1 What Is a Schedule? What Is It Good For? 1.2 Traditional Scheduling Techniques 1.3 Network-Based Scheduling Techniques 1.4 Network-Based Project Management: Basic Steps

Step 1. Defining Activities Step 2. Defming Activity Interdependencies Step 3. Drawing the Network Step 4. Time and Resource Estimation Step 5. Basic Calculations Step 6. Advanced Calculations Step 7. Project Control Step 8. Project Review

1.5 Historical Review

xi

xiii

1 1 2 5 7 7 8 8 9

11 11 12 12 13

vi

CHAPTER 2 CPM Scheduling

2.1 Introducing a Sample Project 2.2 Basic Definitions. Drawing Rules 2.3 Preceding (Succeeding) Activity Lists 2.4 Drawing of an Arrow Diagram

Method I Method 2

2.5 Levels of Network 2.6 CPM Calculations

Usual Procedure Primal-Dual Procedure

2.7 Information Obtained From Calculations 2.8 Pros and Cons of the CPM Technique 2.9 Practical Problems and Solutions

Problems Solutions

2.10 Historical Review

CHAPTER 3 CPM Least Cost Scheduling

3.1 Introducing a Sample Project 3.2 Heuristic Solutions

Fondahl's Method Siemens'Method

3.3 Exact Solution 3.4 Maximal Cost Solution 3.5 Which Is Better? 3.6 Special Cases 3.7 Practical Problems and Solutions

Problems Solutions

3.8 Historical Review

17 18 25 29 33 34 40 46 47 49 53 58 64 71 71 74 78

79 80 84 85 94

100 116 122 124 126 126 127 131

CHAPTER 4 Precedence Diagramming

4.1 Introducing the Sample Project 4.2 Definitions. Precedence Relationships. 4.3 Preceding Activity List 4.4 Drawing of a Network 4.5 PDM Calculation 4.6 Notes on Calculation Rules. 4.7 PDM Calculation: Splitting Allowed 4.8 Loops in PDM Network 4.9 Notes on Negative Lag and Dangling Activities 4.10 The Paradox Behavior ofPDM 4.11 Information Obtained from Calculations

Critical Activities: No Splitting Allowed Activity Floats: No-Splitting Allowed Floats: Precedence Relationships Critical Activities: Splitting Allowed Activity Floats: Splitting Allowed

4.12 Conclusions 4.13 Practical Problems and Solutions

Problems Solutions

4.14 Historical Review

CHAPTERS Advanced Precedence Diagramming

5.1 Introducing the Sample Project 5.2 Maximal Type of Relationships 5.3 Calculations with Maximal Relationships 5.4 Information Obtained from Calculations 5.5 Constraints in PDM

Minimal Type Of Constraints Maximal Type Of Constraints Mixed Type Of Constraints

5.6 PDM Versus CPM 5.7 Practical Problems and Solutions

Problems Solutions

5.8 Historical Review

133 134 137 141 143 144 148 152 155 156 157 158 158 159 160 162 163 164 166 166 167 170

173 174 175 183 189 190 190 191 191 194 196 196 197 200

Vll

viii

CHAPTER 6 Precedence Diagramming With Bounded Activity Duration 203

6.1 Introducing the Sample Project 204 6.2 Calculations With Minimal Relationships 206

Determining the Minimal Project Duration 207 Determining the Maximal Project Duration 209

6.3 Calculations With Maximal Relationships 211 Determining the Minimal Project Duration 211 Determining the Maximal Project Duration 212

6.4 Practical Problems and Solutions 213 Problems 213 Solutions

6.5 Historical Review

CHAPTER 7 PDM Least Cost Scheduling

7.1 Introducing The Sample Project 7.2 Differences Between CPM and PDM Cost Curves 7.3 Exact Solution 7.4 Special Cases 7.5 Practical Problems and Solutions

Problems Solutions

7.6 Historical Review

CHAPTER 8 Resources In Scheduling

8.1 Using Optimal Procedures 8.2 Resource Leveling (Fixed Project Duration) 8.3 Resource Allocation (Limited Resources) 8.4 Maximal Precedence Relationships in Leveling 8.5 Maximal Precedence Relationships in Allocation

215 218

219 220 223 224 238 239 239 240 241

243 244 245 252 256 257

CBAPTER9 Art of Scheduling

9.1 Work Breakdown Structure 9.2 Special Activity Types 9.3 Cash Flow Forecasting, Monitoring And Control

Cash Flow Progress Curves

9.4 Loops In Networks 9.5 Multiproject Scheduling 9.6 Calendar Versus Workday Schedule

APPENDIX A Mathematical Basis

1. Digraph 2. Duality Theorem of Path and Cut 3. Minimal Path - Maximal Potential Problem 4. Maximal Flow Minimal Cut 5. The First "K" Longest Path 6. Linear Programming and Duality 7. Practical Problems and Solutions

Problems Solutions

8. Historical Review

APPENDIX B Computer Applications

1. Choosing Among Available Applications

2. ProjectDirector

BIBLIOGRAPHY

INDEX

259 260 265 268 269 269 271 278 281

285 285 287 291 296 304 309 312 312 314 315

317 317

321

323

329

ix

PREFACE

Industrial, financial, commercial or any kinds of project have at least one common feature: the better organized they are, the higher the profit or the lower the cost. Project management is the principle of planning different projects and keeping them on track within time, cost and resource constraints. The need for effective project management is ever-increasing. The complexity of the environment we live in requires more sophisticated methods than it did just a couple of decades ago. Project managers might face insurmountable obstacles in their work if they do not adapt themselves to the changing circumstances. On the other hand, better knowledge of project management can result in better plans, schedules and, last but not least, more contracts and more profit. This knowledge can help individuals and firms to stay alive in this competitive market and, in the global sense, utilize the finite resources of our planet in a more efficient way.

Project management is a multidiscipline which has emerged to answer practical problems. We address this book to those readers who aspire to a still higher degree of professionalism in management, especially in network techniques. Network techniques are the basic mathematical tools for planning and scheduling any kind of project. Dozens of different network techniques are known in the project management science, but few are used in practice. This book gives a comprehensive overview of deterministic network techniques, the most often used techniques in practice. Special emphasis was put on the Precedence Diagramming

xii

Method, as more than ninety percent of the industrial applications are based on PDM. New theoretical improvements of PDM are also discussed in this book. The introduction of maximal type of precedence relationships and the discussion of PDM time-cost trade-off cannot be found in any other text.

A PC-based software packege called ProjectDirector, containing the theoretical improvements described in this book, is available from the author. It is an improvement over the commercial computer programs. For example, it can handle the maximal type of precedence relationships and shows the critical path characteristics and other improvements described in this book. More information can be found in Appendix B.

The author would appreciate any comments and suggestions for further improvements. Please send your comments to:

Dr. Miklos HAJDU Intemet:MHajdu@eporg.ekt.bme.hu http://www.plansys.hu

Budapest, June 1996 Miklos Hajdu, Ph.D.

ACKNOWLEDGEMENTS

I started to write this book in the summer of 1995 in Holland, where I spent my sabbatical year at the Department of Civil Engineering Informatics at Delft University of Technology. I would like to thank my colleague, Prof. Peter van der Veer, chair of the department, for his continuous support. He also provided me with a quiet and peaceful working environment, which is the most important factor in completing this kind of work.

The author also wishes to express his sincere appreciation to Dr 10zsef Cser and Dr Reza Beheshti, faculty of the department, for their helpful comments during the work.

Finally, I wish to thank Mr. Arpad Horvath from the Department of Civil and Environmental Engineering at Carnegie Mellon University for all of his help, particularly in evaulating and editing the manuscript.