1. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-1 Network Planning Methods Example CPM : Saint Paul’s Hospital Network Planning Methods Example CPM : Saint Paul’s Hospital

2. CPM and PERT CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique) are network based methods designed to assist in the planning, scheduling, and control of projects. A project is a collection of interrelated activities with each activity consuming time and resources. The objective of CPM and PERT is to provide analytic means for scheduling the activities.

3. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-3 Terms Used in Project Management Activity : A certain amount of work or task required in the project Activity duration : In CPM the best estimate of time to complete an activity. In PERT the expected time or average time to complete an activity Critical activity : An activity that has no room for schedule slippages : if it slips the entire the entire project completion will slip. An activity with zero slack

4. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-4 Terms Used in Project Management.cont  Critical path: The chain of critical activities for the project.The longest path through the network  Dummy activity :An activity that consumes no time but shows precedence among activities  Earliest finish (EF): The earliest that an activity can finish from the beginning of the project  Earliest start ( ES): The earliest that an activity can start from the beginning of the project

5. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-5 Terms Used in Project Management.cont  Event :A beginning, a completion point,or a milestone accomplishment within the project. An activity begins and ends with events  Latest finish (LF) : The latest that an activity can finish from the beginning of the project  Latest start (LS) :The latest that an activity can start from the beginning of the project

6. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-6 Terms Used in Project Management.cont  Predecessor activity : An activity that must occur before another activity.  Slack : The amount of time that an activity or group of activities can slip without causing a delay in the completion of the project  Successor activity : An activity that must occur after another activity

7. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-7 Terms Used in Project Management.cont Conventions used in drawing network diagrams (Arrows & Circles )  Activity on Arrow (AOA) : The activities are denoted by Arrows and events are denoted by circles  Activity on Node(AON) : Activities are denoted by circles(or nodes) and the precedence relation ships between activities are indicated by arrows

8. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-8  Relationship between activities  Project duration  Critical path  Slack for non – critical activities  Crashing (cost / time trade-offs)  Resource usage Network planning methods that generate:

9. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-9 St. Paul’s Hospital Immediate Activity Description Predecessor(s) ASelect administrative and medical staff. BSelect site and do site survey. CSelect equipment. DPrepare final construction plans and layout. EBring utilities to the site. FInterview applicants and fill positions in nursing, support staff, maintenance, and security. GPurchase and take delivery of equipment. HConstruct the hospital. IDevelop an information system. JInstall the equipment. KTrain nurses and support staff. — A B A C D A E,G,H F,I,J

10. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-10 St. Paul’s Hospital Immediate Activity Description Predecessor(s) ASelect administrative and medical staff. BSelect site and do site survey. CSelect equipment. DPrepare final construction plans and layout. EBring utilities to the site. FInterview applicants and fill positions in nursing, support staff, maintenance, and security. GPurchase and take delivery of equipment. HConstruct the hospital. IDevelop an information system. JInstall the equipment. KTrain nurses and support staff. — A B A C D A E,G,H F,I,J AON Network FinishStart A B C D E F G H I J K

11. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-11 St. Paul’s Hospital Immediate Activity Description Predecessor(s) ASelect administrative and medical staff. BSelect site and do site survey. CSelect equipment. DPrepare final construction plans and layout. EBring utilities to the site. FInterview applicants and fill positions in nursing, support staff, maintenance, and security. GPurchase and take delivery of equipment. HConstruct the hospital. IDevelop an information system. JInstall the equipment. KTrain nurses and support staff. — A B A C D A E,G,H F,I,J Completion Time FinishStart K9K9 I 15 F 10 C 10 D 10 E 24 G 35 H 40 J4J4 A 12 B9B9

12. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-12 St. Paul’s Hospital Immediate Activity Description Predecessor(s) ASelect administrative and medical staff. BSelect site and do site survey. CSelect equipment. DPrepare final construction plans and layout. EBring utilities to the site. FInterview applicants and fill positions in nursing, support staff, maintenance, and security. GPurchase and take delivery of equipment. HConstruct the hospital. IDevelop an information system. JInstall the equipment. KTrain nurses and support staff. — A B A C D A E,G,H F,I,J Completion Time FinishStart K9K9 I 15 F 10 C 10 D 10 E 24 G 35 H 40 J4J4 A 12 B9B9 Path Expected Time (wks) A-I-K36 A-F-K31 A-C-G-J-K70 B-D-H-J-K72 B-E-J-K46 Critical Path

13. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-13 Critical Path  The longest path in the network  Defines the shortest time project can be completed  Critical path activity delay project delay

14. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-14  Begin at starting event and work forward  ES is earliest start  ES = 0 for starting activities  ES = Maximum EF of all predecessors for non-starting activities  EF is earliest finish  EF = ES + Activity time Earliest Start and Earliest Finish ES LS EF LF Activity Name Activity Duration

15. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-15 A 12 K9K9 C 10 G 35 J4J4 H 40 B9B9 D 10 E 24 I 15 F 10 Finish Start Earliest Start / Earliest Finish

16. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-16 Earliest Start / Earliest Finish Finish Earliest start time Earliest finish time A 12 K9K9 C 10 G 35 J4J4 H 40 B9B9 D 10 E 24 0 12 I 15 F 10 12 27 12 22 63 72 22 57 59 6319 59 9 33 0 9 9 19 12 22 Critical path Start

17. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-17  Begin at ending event and work backward  LF is latest finish  LF = Maximum EF for ending activities  LF = Minimum LS of all successors for non-ending activities  LS is latest start  LS = LF – Activity time Latest Start and Latest Finish ES LS EF LF Activity Name Activity Duration

18. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-18 Latest Start / Latest Finish A 12 K9K9 C 10 G 35 J4J4 H 40 B9B9 D 10 E 24 0 12 I 15 F 10 12 27 12 22 63 72 22 57 59 6319 59 9 33 0 9 9 19 12 22 48 63 2 14 53 63 63 72 14 24 24 59 0 9 9 19 19 59 35 59 59 63 Latest start timeLatest finish time Critical path Finish Start What do you notice about ES/LS & EF/LF?

19. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-19 Activity Slack Analysis A 12 K9K9 C 10 G 35 J4J4 H 40 B9B9 D 10 E 24 0 12 I 15 F 10 12 27 12 22 63 72 22 57 59 6319 59 9 33 0 9 9 19 12 22 48 63 2 14 53 63 63 72 14 24 24 59 0 9 9 19 19 59 35 59 59 63 Latest start timeLatest finish time Critical path Finish Start Slack K = 63 – 63 = 0 or Slack K = 72 – 72 = 0 Slack = LS – ES or Slack = LF – EF

20. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-20 Activity Slack Analysis A 12 K9K9 C 10 G 35 J4J4 H 40 B9B9 D 10 E 24 0 12 I 15 F 10 12 27 12 22 63 72 22 57 59 6319 59 9 33 0 9 9 19 12 22 48 63 2 14 53 63 63 72 14 24 24 59 0 9 9 19 19 59 35 59 59 63 Latest start timeLatest finish time Critical path Finish Start Node DurationESLS Slack A12022 B9000 C1012142 D10990 E2493526 F10125341 G3522242 H4019190 I15124836 J459590 K663630 Activity slack = maximum delay time Critical path activities have zero slack

21. © 2004 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 3-21 Activity Slack How much would we like to reduce the time for activity B? C 15 5 20 10 25 A5A5 0 5 Finish Start B 20 5 25 D 10 25 35

22. A critical path of the project is a path comprising of critical activities of the project. It is to be remembered that a project can have more than one critical path, Any critical path will start at node 1 and will end at node n and that The sum of the durations of the activities lying on a critical path is the duration of the project.