Project Management CPM & PERT PDF

Week 9 Project Management CPM & PERT  Project “A project is a series of activities directed to the accomplishment of a desired objective.” Plan your work first…..then work your plan  Management of Projects 1. Planning - goal setting, defining the project, tea...

Week 9 Project Management CPM & PERT  Project “A project is a series of activities directed to the accomplishment of a desired objective.” Plan your work first…..then work your plan  Management of Projects 1. Planning - goal setting, defining the project, team organization 2. Scheduling - relate people, money, and supplies to specific activities and activities to each other 3. Controlling - monitor resources, costs, quality, and budgets; revise plans and shift resources to meet time and cost demands  Project Management Activities ► Planning ► Objectives ► Scheduling ► Resources ► Project activities ► Work break- down structure ► Start & end times ► Organization ► Network ► Controlling ► Monitor, compare, revise, action Project Planning, Scheduling, and Controlling Time/cost estimates Budgets Engineering diagrams Cash flow charts Material availability details  Project Planning, Scheduling, and Controlling CPM/PERT Gantt charts Milestone charts Cash flow schedules Project Planning, Scheduling, and Controlling Budgets Delayed activities report Slack activities report  A Sample Project Organization President Human Quality Resources Marketing Finance Design Production Mgt Project Project Mechanical Test Technician No. 1 Manager Engineer Engineer Project Project Electrical Computer Technician No. 2 Manager Engineer Engineer Project Management Techniques ► Gantt chart ► Critical Path Method (CPM) ► Program Evaluation and Review Technique (PERT)  A Simple Gantt Chart Time J F M A M J J A S Design Prototype Test Revise Production Originated by H.L.Gantt in 1918  Gantt Chart Graph or bar chart with a bar for each project activity that shows passage of time Provides visual display of project schedule Advantages Limitations - Gantt charts are quite commonly used. - Do not clearly indicate details regarding They provide an easy graphical the progress of activities representation of when activities (might) - Do not give a clear indication of take place. interrelationship between the separate activities  NETWORK TECHNIQUES PERT CPM -Program Evaluation and Critical Path Method Review Technique Developed by El Dupont for - developed by the US Chemical Plant Shutdown Navy with Booz Project- about Hamilton Lockheed same time as PERT - on the Polaris Missile/Submarine program 1958 ✓Both use same calculations, almost similar ✓Main difference is probabilistic and deterministic in time estimation ✓Consider precedence relationships and interdependencies  CPM - Critical Path Method Definition: In CPM, activities are shown as a network of precedence relationships using activity-on-node network construction Single estimate of activity time Deterministic activity times USED IN : Production management - for the jobs of repetitive in nature where the activity time estimates can be predicted with considerable certainty due to the existence of past experience.  PERT - Project Evaluation & Review Techniques Definition: In PERT, activities are shown as a network of precedence relationships using activity-on-arrow network construction Multiple time estimates Probabilistic activity times USED IN : Project management - for non-repetitive jobs (research and development work), where the time and cost estimates tend to be quite uncertain. This technique uses probabilistic time estimates.  Six Steps PERT & CPM 1. Define the project and prepare the work breakdown structure 2. Develop relationships among the activities - decide which activities must precede and which must follow others 3. Draw the network connecting all of the activities 4. Assign time and/or cost estimates to each activity 5. Compute the longest time path through the network – this is called the critical path 6. Use the network to help plan, schedule, monitor, and control the project  Questions PERT & CPM Can Answer 1. When will the entire project be completed? 2. What are the critical activities or tasks in the project? 3. Which are the noncritical activities? 4. What is the probability the project will be completed by a specific date?  Questions PERT & CPM Can Answer 5. Is the project on schedule, behind schedule, or ahead of schedule? 6. Is the money spent equal to, less than, or greater than the budget? 7. Are there enough resources available to finish the project on time? 8. If the project must be finished in a shorter time, what is the way to accomplish this at least cost?  NETWORK Graphical portrayal of activities and event Shows dependency relationships between tasks/activities in a project Clearly shows tasks that must precede (precedence) or follow (succeeding) other tasks in a logical manner Clear representation of plan – a powerful tool for planning and controlling project Example of Simple Network – Survey Slide 19 Example of Network – More Complex Slide 20 Example 1 Activity Predecessor activity A none B none C A D A E B F C G D&E  Example 1 Activity Predecessor activity C A none 2 4 F A B none D C A 1 6 D A B 3 G E B 5 E F C G D&E  Example 2 Activity Predecessor activity A none B A C A D B E C F D ,E  Example 2 3 D B A F 5 6 1 2 C 4 E  DEFINITION OF TERMS IN A NETWORK Activity: any portions of project (tasks) which required by project, uses up resource and consumes time – may involve labor, paper work, contractual negotiations, machinery operations Activity on Arrow (AOA) showed as arrow, AON – Activity on Node Event: beginning or ending points of one or more activities, instantaneous point in time, also called ‘nodes’ Network: Combination of all project activities and the events. Shows the sequential relationships among activities using nodes and arrows PRECEEDING ACTIVITY SUCCESSOR EVENT Slide 25  Classification of activities Predecessor activity: Activities that must be completed immediately prior to the start of another activity are called predecessor activities. Successor activity : activities that cannot be started until one or more of other activities are completed but immediately succeed them are called successor activities. Concurrent activities: activities that can be accomplished together are known as concurrent activities. Dummy activity: An activity which does not consume any resource but merely depicts the dependence of one activity on other is called dummy activity. It is introduced in a network when two or more parallel activities have the same start and finish nodes. Emphasis on Logic in Network Construction Construction of network should be based on logical or technical dependencies among activities Example - before activity ‘Approve Drawing’ can be started, the activity ‘Prepare Drawing’ must be completed Common error – build network on the basis of time logic (a feeling for proper sequence ) see example below WRONG !!! CORRECT ✓ Slide 27  Project Network  Activity-on-node (AON) nodes represent activities, and arrows show precedence relationships  Activity-on-arrow (AOA) arrows represent activities and nodes are events for points in time 28 AOA Project Network 3 Lay foundation Dummy 2 0 Build Finish 3 1 house work 1 2 4 6 7 Design house and Order and 3 1 obtain financing receive Select paint 1 1 Select carpet materials 5 AON Project Network Lay foundations Build house 2 4 Finish work 2 3 7 Start 1 1 3 Design house and 6 obtain financing 3 1 5 1 1 Select carpet Order and receive 29 Select paint materials  A Comparison of AON and AOA Network Conventions Activity on Activity Activity on Node (AON) Meaning Arrow (AOA) A comes before B, which comes before C A and B must both be completed before C can start B and C cannot begin until A is completed  A Comparison of AON and AOA Network Conventions Activity on Activity Activity on Node (AON) Meaning Arrow (AOA) A comes before (a) A B C B, which comes before C A B C A A A and B must both (b) C be completed before C can start C B B B B and C cannot (c) A begin until A is B completed A C C  A Comparison of AON and AOA Network Conventions Activity on Activity Activity on Node (AON) Meaning Arrow (AOA) C and D cannot begin until both A and B are completed C cannot begin until both A and B are completed D cannot begin until B is completed A dummy activity is introduced in AOA  A Comparison of AON and AOA Network Conventions Activity on Activity Activity on Node (AON) Meaning Arrow (AOA) C and D cannot A C begin until both A C (d) A and B are completed B D B D C cannot begin until both A and B are A C completed A C (e) D cannot begin until Dummy activity B is completed B D A dummy activity is introduced in AOA B D  AON Example Table 3.1 Milwaukee Paper Manufacturing’s Activities and Predecessors IMMEDIATE ACTIVITY DESCRIPTION PREDECESSORS A Build internal components — B Modify roof and floor — C Construct collection stack A D Pour concrete and install frame A, B E Build high-temperature burner C F Install pollution control system C G Install air pollution device D, E H Inspect and test F, G  AON Network for Milwaukee Paper Activity A A (Build Internal Components) Start Activity B Start B (Modify Roof and Floor) Activity  AON Network for Milwaukee Paper Activity A Precedes Activity C A C Start B D Activities A and B Precede Activity D  AON Network for Milwaukee Paper F A C E Start H B D G Arrows Show Precedence Relationships  AOA Network for Milwaukee Paper C 2 4 (Construct Stack) H 1 Dummy 6 7 Activity (Inspect/ Test) D 3 5 (Pour Concrete/ Install Frame)  Situations in network diagram B A A must finish before either B or C can start C A C both A and B must finish before C can start B A C both A and B must finish before either of C B or D can start D A B A must finish before B can start Dummy both A and C must finish before D can start C D  Network example Illustration of network analysis of a minor redesign of a product and its associated packaging (AON). The key question is: How long will it take to complete this project ? 40 For clarity, this list is kept to a minimum by specifying only immediate relationships, that is relationships involving activities that "occur near to each other in time". 41 Questions to prepare activity network Is this a Start Activity? Is this a Finish Activity? What Activity Precedes this? What Activity Follows this? What Activity is Concurrent with this? 42  Example 2 Develop the network for a project with following activities and immediate predecessors (AOA): Activity Immediate predecessors A - B - C B D A, C E C F C G D,E,F  Network of first five activities A D 1 3 4 E B C 5 2 We need to introduce a dummy activity  Network of Seven Activities 1 A 3 D 4 G 7 dummy E B dummy C 5 F 2 6 Note how the network correctly identifies D, E, and F as the immediate predecessors for activity G. Dummy activities is used to identify precedence relationships correctly and to eliminate possible confusion of two or more activities having the same starting and ending nodes Dummy activities have no resources (time, labor, machinery, etc) – purpose is to PRESERVE LOGIC of the network  EXAMPLES OF THE USE OF DUMMY ACTIVITY Network concurrent activities a a 2 1 2 1 Dummy b 3 b WRONG!!! RIGHT ✓ Activity c not WRONG ! required for e a a e d 1 b 1 b e d c 2 c WRONG RIGHT !!! ✓ RIGHT ✓  WRONG!!! RIGHT!!! a d a d 1 1 b e b 2 2 4 e c f c f 3 3 a precedes d. a and b precede e, b and c precede f (a does not precede f)  Determining the Project Schedule Perform a Critical Path Analysis ► The critical path is the longest path through the network ► The critical path is the shortest time in which the project can be completed ► Any delay in critical path activities delays the project ► Critical path activities have no slack time  Critical path Those activities which contribute directly to the overall duration of the project constitute critical activities, the critical activities form a chain running through the network which is called critical path. Critical activities : the slack of an activity is the difference between the latest & earliest events time. The events with zero slack time are called as critical events. Critical activities: The difference between latest start time & earliest start time of an activity will indicate amount of time by which the activity can be delayed without affecting the total project duration. Activities with 0 total slack or float are called as critical activities Forward Pass Earliest Start Time (ES) earliest time an activity can start ES = maximum EF of immediate predecessors Earliest finish time (EF) earliest time an activity can finish earliest start time plus activity time EF= ES + t Backward Pass Latest Start Time (LS) Latest time an activity can start without delaying critical path time LS= LF - t Latest finish time (LF) latest time an activity can be completed without delaying critical path time LF = minimum LS of immediate successors 50  Determining the Project Schedule Table 3.1 Milwaukee Paper Manufacturing’s Activities and Predecessors IMMEDIATE ACTIVITY DESCRIPTION PREDECESSORS A Build internal components — B Modify roof and floor — C Construct collection stack A D Pour concrete and install frame A, B E Build high-temperature burner C F Install pollution control system C G Install air pollution device D, E H Inspect and test F, G  Determining the Project Schedule Table 3.2 Time Estimates for Milwaukee Paper Manufacturing ACTIVITY DESCRIPTION TIME (WEEKS) A Build internal components 2 B Modify roof and floor 3 C Construct collection stack 2 D Pour concrete and install frame 4 E Build high-temperature burner 4 F Install pollution control system 3 G Install air pollution device 5 H Inspect and test 2 Total time (weeks) 25 Determining the Project Schedule Perform a Critical Path Analysis Earliest start (ES) = earliest time at which an activity can start, assuming all predecessors have been completed Earliest finish (EF) = earliest time at which an activity can be finished Latest start (LS) = latest time at which an activity can start so as to not delay the completion time of the entire project Latest finish (LF) = latest time by which an activity has to be finished so as to not delay the completion time of the entire project Determining the Project Schedule Activity Format Activity Name or Symbol A Earliest Earliest ES EF Finish Start Latest LS LF Latest Start 2 Finish Activity Duration  Forward Pass Begin at starting event and work forward Earliest Start Time Rule: ► If an activity has only a single immediate predecessor, its ES equals the EF of the predecessor ► If an activity has multiple immediate predecessors, its ES is the maximum of all the EF values of its predecessors ES = Max {EF of all immediate predecessors}  Forward Pass Begin at starting event and work forward Earliest Finish Time Rule: ► The earliest finish time (EF) of an activity is the sum of its earliest start time (ES) and its activity time EF = ES + Activity time  ES/EF Network for Milwaukee Paper ES EF = ES + Activity time Start 0 0 0  ES/EF Network for Milwaukee Paper EF of A = ES ES of A + 2 of A A Start 0 2 0 0 0 2  ES/EF Network for Milwaukee Paper A 0 2 2 EF of B = ES ES of B + 3 0 Start 0 of B B 0 0 3 3  ES/EF Network for Milwaukee Paper A C 0 2 2 4 2 2 Start 0 0 0 B 0 3 3  ES/EF Network for Milwaukee Paper A C 0 2 2 4 2 2 Start 0 0 = Max (2, 3) D 0 3 7 B 0 3 3 4  ES/EF Network for Milwaukee Paper A C 0 2 2 4 2 2 Start 0 0 0 B D 0 3 3 7 3 4  ES/EF Network for Milwaukee Paper A C F 0 2 2 4 4 7 2 2 3 Start E H 0 0 4 8 13 15 0 4 2 B D G 0 3 3 7 8 13 3 4 5  Backward Pass Begin with the last event and work backwards Latest Finish Time Rule: ► If an activity is an immediate predecessor for just a single activity, its LF equals the LS of the activity that immediately follows it ► If an activity is an immediate predecessor to more than one activity, its LF is the minimum of all LS values of all activities that immediately follow it LF = Min {LS of all immediate following activities}  Backward Pass Begin with the last event and work backwards Latest Start Time Rule: ► The latest start time (LS) of an activity is the difference of its latest finish time (LF) and its activity time LS = LF – Activity time  LS/LF Times for Milwaukee Paper A C F 0 2 2 4 4 7 2 2 3 Start E H 0 0 4 8 13 15 13 15 0 4 2 B D – Activity timeG LS = LF 0 3 3 7 8 13 3 4 5 LF = EF of Project  LS/LF Times for Milwaukee Paper A C F 0 2 2 4 4 7 10 13 2 2 3 Start E H 0 0 4 Min(LS 8 of 13 15 LF = following activity) 13 15 0 4 2 B D G 0 3 3 7 8 13 3 4 5  LS/LF Times for Milwaukee Paper LF = Min(4, 10) A C F 0 2 2 4 4 7 2 4 10 13 2 2 3 Start E H 0 0 4 8 13 15 4 8 13 15 0 4 2 B D G 0 3 3 7 8 13 8 13 3 4 5  LS/LF Times for Milwaukee Paper A C F 0 2 2 4 4 7 0 2 2 4 10 13 2 2 3 Start E H 0 0 4 8 13 15 0 0 4 8 13 15 0 4 2 B D G 0 3 3 7 8 13 1 4 4 8 8 13 3 4 5  Computing Slack Time After computing the ES, EF, LS, and LF times for all activities, compute the slack or free time for each activity ► Slack is the length of time an activity can be delayed without delaying the entire project Slack = LS – ES or Slack = LF – EF  Activity Slack Each event has two important times associated with it : - Earliest time , Te , which is a calendar time when an event can occur when all the predecessor events completed at the earliest possible times - Latest time , TL , which is the latest time the event can occur without delaying the subsequent events and completion of project. Difference between the latest time and the earliest time of an event is the slack time for that event Positive slack : Slack is the amount of time an event can be delayed without delaying the project completion  Computing Slack Time TABLE Milwaukee Paper’s Schedule and Slack Times 3.3 EARLIEST EARLIEST LATEST LATEST ON START FINISH START FINISH SLACK CRITICAL ACTIVITY ES EF LS LF LS – ES PATH A 0 2 0 2 0 Yes B 0 3 1 4 1 No C 2 4 2 4 0 Yes D 3 7 4 8 1 No E 4 8 4 8 0 Yes F 4 7 10 13 6 No G 8 13 8 13 0 Yes H 13 15 13 15 0 Yes  Critical Path for Milwaukee Paper A C F 0 2 2 4 4 7 0 2 2 4 10 13 2 2 3 Start E H 0 0 4 8 13 15 0 0 4 8 13 15 0 4 2 B D G 0 3 3 7 8 13 1 4 4 8 8 13 3 4 5  ES – EF Gantt Chart for Milwaukee Paper 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 A Build internal components B Modify roof and floor C Construct collection stack D Pour concrete and install frame E Build high-temperature burner F Install pollution control system G Install air pollution device H Inspect and test  LS – LF Gantt Chart for Milwaukee Paper 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 A Build internal components B Modify roof and floor C Construct collection stack D Pour concrete and install frame E Build high-temperature burner F Install pollution control system G Install air pollution device H Inspect and test Thank You…