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Network Diagramming Network Analysis  The common term for network analysis is PERT  PERT stands for Program Evaluation and Review Technique  The word.

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Presentation on theme: "Network Diagramming Network Analysis  The common term for network analysis is PERT  PERT stands for Program Evaluation and Review Technique  The word."— Presentation transcript:

1

2 Network Diagramming

3 Network Analysis  The common term for network analysis is PERT  PERT stands for Program Evaluation and Review Technique  The word PERT, though, has grown to mean network analysis in general

4 Network Analysis  Goal is to find critical path and bottlenecks Those tasks that have the most schedule pressure What is critical path?

5 Comparison Gantt Chart Milestone Chart

6 PERT CHART

7 Terminology and Symbols Event Activity 46 Start WorkSign Contract

8 Terminology and Symbols Burst Point - Many Tasks Starting when One Finishes

9 Terminology and Symbols Sink - Many Tasks Finishing before One Can Start

10 Performing the Analysis  Forward Pass - Working forward through the network to find earliest start and finish times  Backward Pass - Working backward through the network to find latest start and finish times

11 Earliest Start and Finish Times  The earliest times the tasks can start based on the constraints of the preceding tasks and their relationships to each other.  So, if task A can’t finish till Monday at 5pm, task B can’t start till Monday at 5:01 pm.

12 Latest Start and Finish Times  The latest times the tasks can start and finish based on the succeeding tasks and the ultimate finish time.  If the contract says the end date for the project is March 11th, then the project has to finish March 11th.

13 Slack Time  There are two types of slack: Free slack is float time between tasks based on the relationships of the tasks Introduced slack is the float time built into the network by contract - this is not in book, but is common in networks, also called total slack

14 Example 1

15 AB C D E F G

16 Calculations  Earliest Start = Latest start from proceeding task  Earliest Finish = Earliest Start + Task Length  Latest Finish = Latest Start from Succeeding Task or Contractual Finish  Latest Start = Latest Finish - Task Length

17 Forward Pass No Introduced Slack

18 Example 1 AB C D E F G A ES = 1 EF = = 2 B ES = 2 from A EF = = 5

19 Example 1 AB C D E F G C ES = 5 from B EF = = 9 D ES = 5 from B EF = = 8

20 Example 1 AB C D E F G E ES = 9 from C EF = = 15 F ES = 15 from E (NOT D) always use latest, earliest finish EF = = 18

21 Example 1 AB C D E F G G ES = 18 from F EF = = 19

22 Backward Pass

23 Example 1 AB C D E F G G LF = 19 LS = = 18

24 Example 1 AB C D E F G E LF = 15 from F LS = = 9 F LF = 18 from G LS = = 15

25 Example 1 AB C D E F G C LF = 9 from E LS = = 5 D LF = 15 from F LS = = 12

26 Example 1 AB C D E F G A LF = 2 from B LS = = 1 B LF = 5 from C (NOT D) Use earliest Latest Start LS = = 2

27 Start and Finish Times

28 Critical Path  Critical path (CP) are those tasks with no free slack. So, LS - ES - introduced slack = 0 LF - EF - introduced slack = 0

29 Example 1 AB C D E F G Critical Path has no free slack D has no free slack Critical path in red.

30 Example 2

31 Example 3

32 Estimated Times  When combining data for calculating times the best way is: [best time + (4 X Average) + worst) = ML 6 ML = Most likely

33 Estimated Times  Best time = 14  Average = 17  Worst = 28  [14 + (4 X 17) + 28] = ML = 18.3 or 19


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