Chapter 9 Project Scheduling Networks Duration Estimation and

Chapter 9 Project Scheduling: Networks, Duration Estimation, and Critical Path 09 -01

Chapter 9 Learning Objectives After completing this chapter, students will be able to: �Understand apply key scheduling terminology. �Apply the logic used to create activity networks, including predecessor and successor tasks. �Develop an activity network using Activity-on. Node (AON) techniques. �Perform activity duration estimation based on the use of probabilistic estimating techniques. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -02

Chapter 9 Learning Objectives After completing this chapter, students will be able to: �Construct the critical path for a project schedule network using forward and backward passes. �Identify activity float and the manner in which it is determined. �Calculate the probability of a project finishing on time under PERT estimates. �Understand the steps that can be employed to reduce the critical path. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -03

Project Scheduling �Project scheduling requires us to follow some carefully laid-out steps, in order, for the schedule to take shape. �Project planning, as it relates to the scheduling process, has been defined by the PMBo. K as: The identification of the project objectives and the ordered activity necessary to complete the project including the identification of resource types and quantities required to carry out each activity or task. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -04

Project Scheduling Terms Successors Predecessors Network diagram Serial activities Concurrent activities B D A E F C Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -05

Project Scheduling Terms • Merge activities • Burst activities • Node • Path • Critical Path B D A E F C Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -06

Network Diagrams FIGURE 9. 2 Alternative Activity Networks for Term Paper Assignment Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -07

AOA Versus AON The same mini-project is shown with activities on arc… B E D F C …and activities on node. E D B F C Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -08

Node Labels Early Start Activity Float Late Start ID Number Early Finish Activity Descriptor Activity Duration Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall Late Finish 09 -9

Activity Node Labels Using MS Project 2010 FIGURE 9. 4 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -10

Serial Activities Serial activities are those that flow from one to the next, in sequence. FIGURE 9. 5 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -11

Activities Linked in Parallel (Concurrent) When the nature of the work allows for more than one activity to be accomplished at the same time, these activities are called concurrent and parallel project paths are constructed through the network. FIGURE 9. 6 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -12

Merge Activity FIGURE 9. 7 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -13

Burst Activity FIGURE 9. 8 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -14

Complete Activity Network FIGURE 9. 10 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -15

Developing the Activity Network Using MS Project 2010 FIGURE 9. 11 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -16

Duration Estimation Methods Past experience Expert opinion Mathematical derivation – Beta distribution Most likely (m) Most pessimistic (b) Most optimistic (a) Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -17

FIGURE 9. 14 Symmetrical (Normal) Distribution for Activity Duration Estimation Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -18

FIGURE 9. 15 Asymmetrical (Beta) Distribution for Activity Duration Estimation Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -19

Activity Duration and Variance Table 9. 2 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -20

Constructing the Critical Path Forward pass – an additive move through the network from start to finish Backward pass – a subtractive move through the network from finish to start Critical path – the longest path from end to end which determines the shortest project length Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -21

Rules for Forward/Backward Pass Forward Pass Rules (ES & EF) ES + Duration = EF EF of predecessor = ES of successor Largest preceding EF at a merge point becomes EF for successor Backward Pass Rules (LS & LF) LF – Duration = LS LS of successor = LF of predecessor Smallest succeeding LS at a burst point becomes LF for predecessor Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -22

Project Delta Information Table 9. 4 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -23

FIGURE 9. 16 Partial Project Activity Network with Task Durations Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -24

FIGURE 9. 18 Activity Network with Forward Pass Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -25

FIGURE 9. 19 Activity Network with Backward Pass Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -26

FIGURE 9. 20 Project Network with Activity Slack and Critical Path Note: Critical path is indicated with bold arrows. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -27

AON Network with Laddering Effect FIGURE 9. 24 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -28

Laddering Activities Project ABC can be completed more efficiently if subtasks are used A(3) A 1(1) B(6) A 2(1) B 1(2) Laddered ABC=12 days C(9) ABC=18 days A 3(1) B 2(2) C 1(3) Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall B 3(2) C 2(3) C 3(3) 09 -29

Example of a Hammock Activity FIGURE 9. 25 Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -30

Reducing the Critical Path Eliminate tasks on the CP Convert serial paths to parallel when possible Overlap sequential tasks Shorten the duration on critical path tasks Shorten early tasks longest tasks easiest tasks that cost the least to speed up Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -31

Summary 1. Understand apply key scheduling terminology. 2. Apply the logic used to create activity networks, including predecessor and successor tasks. 3. Develop an activity network using Activity-on. Node (AON) techniques. 4. Perform activity duration estimation based on the use of probabilistic estimating techniques. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -32

Summary 5. Construct the critical path for a project schedule network using forward and backward passes. 6. Identify activity float and the manner in which it is determined. 7. Calculate the probability of a project finishing on time under PERT estimates. 8. Understand the steps that can be employed to reduce the critical path. Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -33

Copyright © 2013 Pearson Education, Inc. Publishing as Prentice Hall 09 -34