Arrow

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Arrow

  1. 1. Network Schedule• Predominant Network Scheduling Techniques: – Critical Path Method (CPM) – Program Evaluation and Review Technique (PERT)Spring Arrow Diagramming 12008, King Saud Dr. Khalid Al-Gahtani
  2. 2. Critical Path Method (CPM)• CPM is a graphical network-based scheduling techniques that when applied intelligently and honestly can be an excellent tool in project management.• The CPM uses a graphic presentation of the planned sequence of activities of a project.Spring Arrow Diagramming 22008, King Saud Dr. Khalid Al-Gahtani
  3. 3. CPM Network• Diagrammatically illustrates all interdependencies of the project’s activities.• Used as a basis for: – Scheduling the total project time – Establishing priorities.Spring Arrow Diagramming 32008, King Saud Dr. Khalid Al-Gahtani
  4. 4. CPM Network• Can be used for integrating: – Time – Cost – Available resources• Establishes a critical path for efficient use of resources• Determine how much time each of the project activities may be delayed without affecting the completion time of the project as determined in objective number one.Spring 2008, Arrow Diagramming 4King Saud University Dr. Khalid Al-Gahtani
  5. 5. CPM Network Drawing Schemes• Arrow Diagramming (Activity-On-Arrow, AOA).• Node Diagramming (Activity-On-Node, AON)Spring 2008, Arrow Diagramming 5King Saud University Dr. Khalid Al-Gahtani
  6. 6. Activity-On-Arrow Method• Arrows: – Original Network Scheduling Technique – Uses a 2 nodes scheme – Diagram easily time scaled.• Nodes: – Commonly called events – Mark points in time – Represent the beginning or end of the time available for a given activity.• Links: – Represent activitiesSpring 2008, Arrow Diagramming 6King Saud University Dr. Khalid Al-Gahtani
  7. 7. Activity-On-Arrow Method• Dummy Activities: – Dummy Activity is a fictitious activity that has no time duration and requires no resource utilization. – Dummy activities used to develop correct representation. – Always break up a dummy activity at the tail, not at the head of the arrow.Spring Arrow Diagramming 72008, King Saud Dr. Khalid Al-Gahtani
  8. 8. Activity-On-Arrow Method – Remove redundant dummy activities – Use unique numbering system for events. – Allow for addition of future activities – Try to number events such that the “i” node is less than the “j” node.Spring 2008, Arrow Diagramming 8King Saud University Dr. Khalid Al-Gahtani
  9. 9. Drawing AOA Networks• Prerequisites: – List of all activities comprising the project – Order of precedence of each activity – Duration estimate of each activitySpring 2008, Arrow Diagramming 9King Saud University Dr. Khalid Al-Gahtani
  10. 10. Drawing AOA Networks• Basic Rules of Network Logic 1. Before an activity may begin, all activities preceding it must be completed. (Activities with no predecessors are self-actuating when the project begins.) 2. Arrows imply logical precedence only. Neither the length of the arrow not its “compass” direction on the drawing have any significance.Spring 2008, Arrow Diagramming 10King Saud University Dr. Khalid Al-Gahtani
  11. 11. Example: Depends on Duration (Day)Activity (Immediate Predecessor(s)) (Time to perform) a ─ 14 b ─ 3 c ─ 7 d a, b 4 e b, c 10Spring 2008, Arrow Diagramming 11King Saud University Dr. Khalid Al-Gahtani
  12. 12. Bar Chart 14a 3b 7c 18d 17eSpring 2008, Arrow Diagramming 12King Saud University Dr. Khalid Al-Gahtani
  13. 13. Activity on arrow a d b D um m y c eSpring Arrow Diagramming 132008, King Saud Dr. Khalid Al-Gahtani
  14. 14. Common Errors in AOA• Dangling (AOA only).• Looping.• Redundancy (AOA only)• Unique Activity Designation• Possible of showing Improper LogicSpring Arrow Diagramming 142008, King Saud Dr. Khalid Al-Gahtani
  15. 15. Dangling 8 6 7 10 11 13 9 12 (8) and (9) are left dangling as they are not the last activities.Spring 2008, Arrow Diagramming 15King Saud University Dr. Khalid Al-Gahtani
  16. 16. Looping f g a i e h b d c Looping error results when an endless loop is shown in the diagram and you can not progress beyond it.Spring 2008, Arrow Diagramming 16King Saud University Dr. Khalid Al-Gahtani
  17. 17. Redundancy 2 3 D um m y 4 Dummy 2-4 is unnecessary as it is not needed for network analysis.Spring Arrow Diagramming 172008, King Saud Dr. Khalid Al-Gahtani
  18. 18. Unique Activity Designation a) 11 10 15 b) 10 15Spring 2008, Arrow Diagramming 18King Saud University Dr. Khalid Al-Gahtani
  19. 19. Possible of showing improper Logic A ctivity A A ctivity C Pla c e C o n cr ete In sta ll pr e finish e da) Sla b in ga ra g e sho p ca bin e ts 10 20 25 A ctivity B A ctivity D In sta ll ga ra ge In sta ll ga ra ge do or op e n er 15 30 In a) A ctivity D depends on A and B A ctivity A A ctivity C Pla c e C o n cr ete In sta ll pr e finish e db) Spring 2008, Sla b in ga ra g e Arrow Diagramming p ca bin e ts sho 19 10 King Saud University Dr. Khalid0 2 Al-Gahtani 25
  20. 20. Possible of showing improper Logic In a) A ctivity D depends on A and B A ctivity A A ctivity C Pla c e C o n cr ete In sta ll pr e finish e db) Sla b in ga ra g e sho p ca bin e ts 10 20 25 A ctivity B A ctivity D In sta ll ga ra ge In sta ll ga ra ge do or op e n er 15 20 30 In b) A ctivity D depends on B only.Spring Arrow Diagramming 202008, King Saud Dr. Khalid Al-Gahtani
  21. 21. Possible of showing improper Logic A ctivity A A ctivity D a) In sta ll W a llb oa rd 10 Pa in t W a ll 25 40 A ctivity B In sta ll v in yl A ctivity E flo oring In sta ll ba se trim 15 30 45 A ctivity C A ctivity F In sta ll C a rp et In sta ll floor r eg ister s 20 35 50 In a) A ctivity F depends on A , B, and C .Spring Arrow Diagramming 212008, King Saudctivity A A Dr. Khalid Al-Gahtani A ctivity D
  22. 22. 20 35 50 In a) A ctivity F depends on A , B, and C .Possible of showing improper Logic A ctivity A A ctivity D b) In sta ll W a llb oa rd 10 Pa in t W a ll 25 40 A ctivity B In sta ll v in yl A ctivity E flo orin g In sta ll ba se trim 15 30 31 45 A ctivity C A ctivity F In sta ll C a rp et In sta ll floor r eg ister s 20 35 50 In b) A ctivity F depends only on B and C .Spring 2008, Arrow Diagramming 22King Saud University Dr. Khalid Al-Gahtani
  23. 23. Disadvantages of Arrow Notation• We may need to use “dummy activities”• Project Management is done on activity basis• Does not give all details of the activity on network diagram• Arrow would be very long, and don’t relate to time. The network is not time scaledSpring 2008, Arrow Diagramming 23King Saud University Dr. Khalid Al-Gahtani
  24. 24. Disadvantages of Arrow Notation 3 9 A 6 B C 2 5Dangling possible if B dos not have successors, B dangles.Spring 2008, Arrow Diagramming 24King Saud University Dr. Khalid Al-Gahtani
  25. 25. Class work#1: A ct ivit y D epend s upo n A ct ivit y D epend s upo n A G F B A I F F A J H H A K I, J, F C B, A L G, D, E D B M K E C N L, MSpring 2008, Arrow Diagramming 25King Saud University Dr. Khalid Al-Gahtani
  26. 26. Class work#1: C E B D L A F G N H I M J KSpring 2008, Arrow Diagramming 26King Saud University Dr. Khalid Al-Gahtani

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