Programming and Scheduling Techniques Construction Management

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Transcript of Programming and Scheduling Techniques Construction Management

PROGRAMMING AND SCHEDULING TECHNIQUES

Thomas E Uher

PROGRAMMING AND SCHEDULING TECHNIQUES

UNSW PRESS

A UNSW Press book Published by University of New South Wales Press Ltd University of New South Wales UNSW Sydney NSW 2052 AUSTRALIA www.unswpress.com.au Thomas Uher 2003 First published 2003 This book is copyright. Apart from any fair dealing for the purpose of private study, research, criticism or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission. Inquiries should be addressed to the publisher. National Library of Australia Cataloguing-in-Publication entry: Uher, Thomas E. (Thomas Edward). Programming and scheduling techniques. Bibliography. ISBN 0 86840 725 9. 1. Building Superintendence. 2. Production scheduling. 3. Network analysis (Planning). 4. Project management. 5. Construction industry Management. 6. Construction industry Planning. I. Title. (Series: Construction management series (Sydney, NSW)). 692.5068 Printer BPA Cover design and photography Di Quick

CONTENTSPreface Abbreviations CHAPTER 1 THE CONCEPT OF PLANNING Introduction Planning process Types of planning activities Planning tools and techniques Planning of construction projects Planning tasks at different stages of the project lifecycle Examples of construction plans and schedules Summary CHAPTER 2 BAR CHARTS Introduction What is a bar chart? Linked bar chart Process of developing a bar chart Activity duration Risk contingency Method statement Summary CHAPTER 3 THE CRITICAL PATH METHOD Introduction A brief history of the critical path method Arrow method Precedence method Concept of link lag Summary Exercises CHAPTER 4 RESOURCE MANAGEMENT Introduction Resources Distribution of resources Resource levelling ix x 1 1 2 7 8 9 16 22 25 26 26 26 28 29 30 33 34 37 38 38 39 40 54 63 67 68 72 72 74 74 77

Resource levelling performed by computers Managing the labour resource Managing materials Managing plant and equipment Summary Exercises CHAPTER 5 OVERLAPPING NETWORK MODELS Introduction Finish-to-start link (FTS) Start-to-start link (STS) Finish-to-finish link (FTF) Start-to-finish link (STF) A compound link Free and total float in overlapped networks Calculating an overlapped critical path schedule Overlapping of critical path schedules by computer Redundant links in precedence schedules Summary Exercises CHAPTER 6 PROJECT CONTROL Introduction Project performance outcomes Project control system Monitoring performance Evaluating performance Adjustments/updates Example of monitoring, evaluation and adjusting or updating of a critical path schedule Costtime optimisation Earned value Summary Exercises CHAPTER 7 CRITICAL PATH SCHEDULING BY COMPUTER Introduction Brief overview of Primavera Project Planner P3 software Scheduling a residential project using Primavera P3 Overlapping models in Primavera P3 Summary

86 87 90 92 96 97 101 101 102 103 105 107 108 110 111 117 118 118 119 122 122 122 123 124 127 129 129 132 146 152 152 157 157 158 161 178 180

CHAPTER 8 CRITICAL CHAIN SCHEDULING Introduction Shortcomings of the critical path method Theory of constraints Critical chain scheduling Summary CHAPTER 9 MULTIPLE ACTIVITY CHARTS Introduction Format of a multiple activity chart Preparation of a multiple activity chart Example of MAC scheduling Summary Exercises CHAPTER 10 THE LINE OF BALANCE TECHNIQUE Introduction Concept of line of balance Concept of delivery program in LOB Developing a LOB schedule Developing a LOB schedule for projects requiring multiple crews Summary Exercises CHAPTER 11 WORK STUDY Introduction Method study Work measurement Summary Exercises CHAPTER 12 RISK AND SCHEDULING Introduction Risk and uncertainty Principles of risk management Risk management plan Probability scheduling Summary CHAPTER 13 THE PROGRAM EVALUATION AND REVIEW TECHNIQUE (PERT) Introduction Network construction

181 181 181 184 185 187 188 188 189 190 192 200 200 206 206 207 209 212 216 222 222 224 224 226 236 249 249 251 251 252 253 266 266 270 271 271 272

The probability concept in PERT The computational process in PERT Example of a PERT schedule An alternative approach to PERT Summary Exercises References Index

273 277 278 281 283 284 287 290

PREFACEPlanning is an important management function and its effective execution is a condition precedent for successful project outcomes. This book addresses operational rather than strategic aspects of planning of construction projects. It describes specific scheduling techniques and processes commonly used in the construction industry. While used mainly at the construction stage, the described techniques and processes are suitable for application across all the stages of the project life cycle. Many books have been written on aspects of construction scheduling, but they largely focus on the critical path method and do not provide a comprehensive review of a range of scheduling techniques. This book attempts to redress this problem. While this book serves as a reference for construction industry practitioners, it has mainly been written as a text and reference material for students studying architecture, building, construction management and civil engineering, and for quantity surveying undergraduate and postgraduate programs. The bulk of the book describes deterministic scheduling techniques, but the last two chapters introduce the concept of probability scheduling using Monte Carlo simulation and PERT. The book examines scheduling techniques such as the bar chart, critical path method, multiple activity chart and line of balance. It includes a brief chapter on critical chain scheduling and describes its main features. Although not a scheduling technique, work study has nevertheless been included since it assists planners and project managers in developing efficient production methods. Practical exercises at the ends of chapters have detailed solutions posted on the UNSW Press website: http://www.unswpress.com.au T.E. Uher

ABBREVIATIONS

ACWP AS BAC BCWP BCWS CCM CCS CIM CPI CPM CV DEP EAC EFD ES ESD ESTM EV FF FTS FTF ID LSD LFD LOB LSM LSMh

Actual cost for work performed Activity slack Budget at completion Budget cost for work performed Budget cost for work schedule Critical chain management Critical chain scheduling Control interval and memory Cost performance index Critical path method Cost variance Department Estimate at completion Earliest finish date Event slack Earliest start date Estimating department Earned value Free float Finish-to-start Finish-to-finish Identification code Latest start date Latest finish date Line of balance Linear scheduling method Linear scheduling model

MAC MAX MBO MIN PC PERT RPM RUF SPI STS STF SV TF TOS VPM WBS

Multiple activity chart Maximum Management by objectives Minimum Percentage complete Program evaluation and review technique Repetitive project modelling Resource utilisation factor Scheduled performance index Start-to-start Start-to-finish Scheduled variance Total float Theory of constraints Vertical production method Work breakdown structure

CHAPTER 1

THE CONCEPT OF PLANNING

INTRODUCTIONThe purpose of this chapter is to introduce the concept of planning, and in particular operational planning. A systematic approach to planning will be discussed first, followed by a brief review of different types of planning activities such as strategic, operational and co-ordinative. A range of planning tools and techniques will then be examined, followed by a discussion on important issues relevant to planning of construction projects. In particular, the distinction will be made between time and resource scheduling. In the next section, an overview of specific planning tasks employed in individual stages of the project life cycle will be given. Finally, examples of plans, programs and schedules used in the construction industry will be illustrated. Planning is one of the four main functions of management. Together with organising, control and leading, it forms the foundation pillars of effective management (Robbins et al. 2000). In simple terms, planning is a process of forecasting future outcomes that may be uncertain or even unknown. It means assessing the future and making provision for it by gathering facts and opinions in order to formulate an appropriate course of action. Planning thus develops a strategy and defines expected outcomes (objectives) for undertaking a specific task before committing to such a task. Once a planning strategy has been determined and objectives defined for a specific task, the manager will select and allocate necessary resources for carrying out the work. This is referred to as organising. It is the second of the four most important management functions.

1 The concept of planning

Because a plan is only a forecast of some specific future events whose outcomes are uncertain, it would be unreasonable to expect it to be accurate. Realistically, the manager must expect the actual progress to deviate from the plan. Accepting that some deviation will occur, the manager will look for it by monitoring the progress, evaluating deviations from the plan and replanning accordingly. This process is referred to as control. It is the third of the four important management functions. Planning, organising and control functions are closely linked within a typical production process. This is illustrated graphically in Figure 1.1.Figure 1.1 A typical production process

Planning is the foundation stone of control. It would be pointless to develop a plan if there was no attempt to control its implementation. Effective control of the production process involves its continuous monitoring, evaluation and adjustment. The control process needs to be dynamic to reflect changing circumstances caused by issues such as: fluctuations in the lev