Cpm n pert
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1) PERT and CPM are network analysis techniques used to schedule, coordinate, and control complex projects. They analyze the tasks involved in a project and their interdependencies to estimate project duration and identify the critical path. 2) The document discusses key aspects of PERT and CPM including activity networks, time estimates, critical path identification, and slack calculations. It also provides an example of applying PERT/CPM to schedule a construction project. 3) PERT and CPM both help answer questions about project completion date, start/finish times of tasks, critical tasks, and float or slack times. The example project demonstrates how its network diagram can be used to determine a 44-week schedule with identified
Cpm n pert
- 1. CPM AND PERT PRESENTED BY – Jitendra, Jay, Nidhi, Saloni, Sheetu Project Management FACULTY OF ARCHITECTURE & EKISTICS JAMIA MILLIA ISLAMIA NEW DELHI – 110025 2016
- 2. “A project is a series of activities directed to accomplishment of a desired objective.” For example – major event like a wedding or Any construction project What is a Project? What is a Project Network? A flow chart that graphically depicts the sequence, interdependencies, and start and finish times of the project through the network.
- 3. Provides the basis for scheduling labor and equipment Enhances communication among project participants Provides an estimate of the project’s duration Provides a basis for budgeting cash flow Identifies activities that are critical and can not be delayed Benefits of Project Network
- 4. Activity-on-Node (AON): Uses nodes to represent the activity and arrows to represent precedence relationships It is activity oriented Activity-on-Arrow (AOA): Uses arrows to represent the activities and nodes to represent events It is event oriented Network Diagrams 1 876 54 3 2 Dummy Activity is used to clarify the precedence relationships between the two activities. It is a zero time activity and consumes no resources.
- 5. Advantages - • Gantt charts are quite commonly used. • They provide an easy graphical representation of when activities (might) take place. Limitations - • Do not clearly indicate details regarding the progress of activities • Do not give a clear indication of interrelationship between the separate activities Gantt chart
- 6. Network Planning Techniques PERT CPM Program Evaluation & Review Technique Critical Path Method step-by-step project management technique for process planning that defines – critical and non-critical tasks with the goal of preventing time-frame problems. ideally suited to projects consisting of numerous activities that interact in a complex manner Project management technique that shows the time taken by each component of a project, and the total time required for its completion. PERT breaks down the project into events and activities, and lays down their proper sequence, relationships, and duration in the form of a network.
- 7. CPM • Critical path is the sequence of activities between a project’s start and finish that takes the longest time to complete. • CPM was developed by Du Pont and the emphasis was on the trade-off between the cost of the project and its overall completion time. Specify the individual activities Determin e the sequence of the activities Draw the network diagram Estimate the activity completion time Identify the critical path Update the CPM diagram Steps In Determining Critical Path
- 8. Provides a graphical view of the project. Predicts the time required to complete the project. Shows which activities are critical to maintaining the schedule and which are not. CPM Benefits While CPM is easy to understand and use, it does not consider the time variations that can have a great impact on the completion time of a complex project. CPM was developed for complex but fairly routine projects with minimum uncertainty in the project completion times. For less routine projects there is more uncertainty in the completion times, and this uncertainty limits its usefulness. Limitations of CPM
- 9. Time Estimation in CPM Time estimates include: Total time for completion. ES- Earliest start time: the earliest time at which the activity can start given that its precedent activities must be completed first. EF-Earliest finish time: equals to the earliest start time for the activity plus the time required to complete the activity. ( EF = ES + time required to complete the activity) LF- Latest finish time: the latest time in which the activity can be completed without delaying the project. LS- Latest start time: equal to the latest finish time minus the time required to complete the activity. ( LS = LF – time required to complete the activity)
- 10. Forward Pass: The early start and early finish times are calculated by moving forward through the network and considering the predecessor activities. Backward Pass: The latest start and finish times are calculated by moving backward through the network. Slack Time: Slack time for an activity is the difference between its earliest and latest start time or between the earliest and latest finish time. Critical path is the path of activities having zero Slack time.
- 11. ES Earliest Starting (time) EF Earliest Finishing LS Latest Starting LF Latest Finishing Slack Difference Time
- 13. PERT • In PERT activities are shown as a network of precedence relationships using activity- on-arrow network construction • PERT was developed by the US Navy for the planning and control of the Polaris missile program and the emphasis was on completing the program in the shortest possible time. Identify the specific activities Determine proper sequence of the activities Draw the network diagram Estimate the time required for each activity Determi ne the critical path Update the PERT chart Steps In PERT
- 14. PERT is useful because it provides the following information: Expected project completion time. Probability of completion before a specified date. The critical path activities that directly impact the completion time. Activities start and end dates. PERT Benefits Limitations of PERT The activity time estimates are somewhat subjective and depend on judgment, so there may be biasedness in the estimate.
- 15. o Optimistic time (to) – It is the shortest time in which the activity can be completed. o Most likely time (tm) – It is the probable time required to perform the activity. o Pessimistic time (tp) – It is the longest estimated time required to perform an activity. o Expected time, te = to + 4tm + t 6 Time Estimation in PERT
- 16. Activity Description Precedence Optimistic time Most Likely time Pessimistic time Expected time A Initial design - 12 16 26 17 B Survey market A 6 9 18 10 C Build prototype A 8 10 18 11 D Test prototype C 2 3 4 3 E Redesigning B,D 3 4 11 5 F Market testing E 6 8 10 8 G Set up production F 15 20 25 20
- 17. 1 7652 3 4 A-B-E-F-G = 60 A-C-D-E-F-G = 64 (CRITICAL PATH)
- 18. Both CPM and PERT - PERT and CPM have been used to plan, schedule, and control a wide variety of projects: R&D of new products and processes Construction of buildings and highways Maintenance of large and complex equipment Design and installation of new systems PERT/CPM is used to plan the scheduling of individual activities that make up a project. PERT/CPM can be used to determine the earliest/latest start and finish times for each activity, the entire project completion time and the slack time for each activity. PERT and CPM are similar in their basic approach, they do differ in the way activity times are estimated. For each PERT activity three times (optimistic, pessimistic and most likely times) are combined to determine the expected activity completion time and its variance. Thus, PERT is a probabilistic technique: it allows us to find the probability of the entire project being completed by any given date. CPM, on the other hand, is called a deterministic approach. It uses two time estimate, the normal time and the crash time, for each activity
- 19. 1. When will the entire project be completed? 2. What are the critical activities or tasks in the project, that is, the ones that will delay the entire project if they are late? 3. Which are the noncritical activities, that is, the ones that can run late without delaying the whole project’s completion time? 4. What is the probability that the project will be completed by a specific date? 5. At any particular date, is the project on schedule, behind schedule, or a head of the schedule? 6. On any given date, is the money spent equal to, less than, or greater than the budgeted amount? 7. Are there enough resources available to finish the project on time? 8. If the project is to be finished in a shorter amount of time, what is the best way to accomplish this at the least cost? (crash analysis) Questions answered by PERT & CPM
- 20. CPM PERT CPM uses activity oriented network. PERT uses event oriented Network. Durations of activity may be estimated with a fair degree of accuracy. Estimate of time for activities are not so accurate and definite. It is used extensively in construction projects. It is used mostly in research and development projects, particularly projects of non-repetitive nature. Deterministic concept is used. Probabilistic model concept is used. CPM can control both time and cost when planning. PERT is basically a tool for planning. In CPM, cost optimization is given prime importance. The time for the completion of the project depends upon cost optimization. The cost is not directly proportioned to time. Thus, cost is the controlling factor. In PERT, it is assumed that cost varies directly with time. Attention is therefore given to minimize the time so that minimum cost results. Thus in PERT, time is the controlling factor.
- 21. The Reliable Construction Company Project CASE STUDY The RELIABLE CONSTRUCTION COMPANY has just made the winning bid of $5.4 million to construct a new plant for a major manufacturer. The manufacturer needs the plant to go into operation within a year. Therefore, the contract incudes the following provisions: A penalty of $300,000 if Reliable has not completed construction by the deadline 47 weeks from now. To provide additional incentive for speedy construction, a bonus of $150,000 will be paid to Reliable if the plant is completed within 40 weeks. Thus, Manager of construction company will need to arrange for a number of crews to perform the various construction activities at different times. Table 10.1 shows his list of the various activities. The third column provides important additional information for coordinating the scheduling of the crews.
- 22. Activity list for the Reliable Construction Co. project Table 1 The top entries in this column indicate that :- 1. Excavation does not need to wait for any other activities. 2. Excavation must be completed before starting to lay the foundation. 3. The foundation must be completely laid before starting to put up the rough wall, etc. When a given activity has more than one immediate predecessor, all must be finished before the
- 23. The spreadsheet used by MS Project for entering the activity list for the Reliable Construction Co. project. On the right is a Gantt chart showing the project schedule. Grantt Chart
- 24. Scheduling A Project With Pert/Cpm The project manager for the Reliable Construction Co. project, wants to use PERT/CPM to develop answers to a series of questions. questions that will be answered Question 1: What is the total time required to complete the project if no delays occur? Question 2: When do the individual activities need to start and finish (at the latest) to meet this project completion time? Question 3: When can the individual activities start and finish (at the earliest) if no delays occur? Question 4: Which are the critical bottleneck activities where any delays must be avoided to prevent delaying project completion? Question 5: For the other activities, how much delay can be tolerated without delaying project completion? Figure 1 -The project network for the Reliable Construction Co. project. The project network in Fig.1 enables answering all these questions by providing two crucial pieces of information, namely, the order in which certain activities must be performed and the (estimated) duration of each activity.
- 25. The Critical Path The (estimated) project duration equals the length of the longest path through the project network. This longest path is called the critical path. (If more than one path tie for the longest, they all are critical paths.) Thus, for the Reliable Construction Co. project, we have Critical path: START ABCEFJLN FINISH (Estimated) project duration 44 weeks. The Paths And Path Lengths Through Reliable’s Project Network Table 2 The six paths through the project network in Fig.1 are given in Table 2, along with the calculations of the lengths of these paths. The path lengths range from 31 weeks up to 44 weeks for the longest path (the fourth one in the table).
- 26. Scheduling Individual Activities Figure 2 - Earliest start time (ES) and earliest finish time (EF) values for the initial activities in Fig.1 that have only a single immediate predecessor. The PERT/CPM scheduling procedure begins When can the individual activities start and finish (at the earliest) if no delays occur? Having no delays means that (1) The actual duration of each activity turns out to be the same as its estimated duration and (2) Each activity begins as soon as all its immediate predecessors are finished.
- 27. Figure 3 - Earliest start time (ES) and earliest finish time (EF) values for all the activities (plus the START and FINISH nodes) of the project. Figure 4 - Latest start time (LS) and latest finish time (LF) for all the activities (plus the START and FINISH nodes) of the project.
- 28. To identify slack, it is convenient to combine the latest times in Fig.4 and the earliest times in Fig.3 into a single figure. Figure 5 - The complete project network showing ES and LS (in parentheses above the node) and EF and LF (in parentheses below the node) for each activity of the project. The darker arrows show the critical path through the project network. Identifying Slack In The Schedule Table 3 Slack for Reliable’s activities Each activity with zero slack is on a critical path through the project network such that any delay along this path will delay project completion. Thus, the critical path is START ABCEFJLN FINISH The slack for an activity is the difference between its latest finish time and its earliest finish time. In symbols. Slack LF - EF.
- 29. Review Question 1: What is the total time required to complete the project if no delays occur? This is the earliest finish time at the FINISH node (EF 44 weeks), as given at the bottom of Fig. 3 and Fig 5 Question 2: When do the individual activities need to start and finish (at the latest) to meet this project completion time? These times are the latest start times (LS) and latest finish times (LF) given in Fig 4 and 5. These times provide a “last chance schedule” to complete the project in 44 weeks if no further delays occur. Question 3: When can the individual activities start and finish (at the earliest) if no delaysoccur? These times are the earliest start times (ES) and earliest finish times (EF) given in Fig 3 and 5 These times usually are used to establish the initial schedule for the project. (Subsequent delays may force later adjustments in the schedule.) Question 4: Which are the critical bottleneck activities where any delays must be avoided to prevent delaying project completion? These are the activities on the critical path shown by the darker arrows in Fig. 5. needs to focus most of his attention on keeping these particular activities on schedule in striving to keep the overall project on schedule. Question 5: For the other activities, how much delay can be tolerated without delaying project completion? These tolerable delays are the positive slacks given in the middle column of Table 3.
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