Lecture 3 - Project Planning - Contd.pptx

Engineering Project Planning
Network Diagram
Work Breakdown Structure
Construction Planning

1. Planning – Contd. M Bilal Zahid

2. Network Diagrams A network is a logical and chronological graphic representation of the activities (and events) composing a project. Network diagrams are the preferred technique for showing activity sequencing. 2

3. Network Diagrams 3

4. Network Diagrams Two methods: arrow networks and node networks. 4 One type is the activity-on-arc (AOA) project network, where each activity is represented by an arc. A node is used to separate an activity (an outgoing arc) from each of its immediate predecessors (an incoming arc). The sequencing of the arcs thereby shows the precedence relationships between the activities. The second type is the activity-on-node (AON) project network, where each activity is represented by a node. Then the arcs are used just to show the precedence relationships that exist between the activities. In particular, the node for each activity with immediate predecessors has an arc coming in from each of these predecessors.

5. Network Diagrams AON has several advantages over AOA: AON project networks are considerably easier to construct than AOA project networks. AON project networks are easier to understand than AOA project networks for inexperienced users, including many managers. AON project networks are easier to revise than AOA project networks when there are changes in the project. 5

6. Network Diagrams In addition: There is no need for the use of dummy activities in AON representation. In AOA, an activity can only start when all it predecessors have finished. AON allows for overlap/lag representation. For these reasons, AON are more popular these days. 6

7. Arrow Diagramming Method (ADM) 7

8. Arrow Diagramming Method (ADM) Also called activity-on-arrow (AOA) network diagram or (I-J) method (because activities are defined by the from node, I, and the to node, J) Activities are represented by arrows. Nodes or circles are the starting and ending points of activities. Can only show finish-to-start dependencies. 8

9. Arrow Diagramming Method (ADM) 9 i j (a) Basic Activity Activity Name Node (Event) i j > i Each activity should have a unique i – j value Node (Event) j

10. Arrow Diagramming Method (ADM) 10 2 A (b) Independent Activities 4 10 B 12 3 A 6 B 9 (c) Dependent Activities

11. Arrow Diagramming Method (ADM) 11 (f) A Cross 20 18 C 16 D 14 A 12 B Activities C and D both depend upon the completion of Activities A and B

12. Arrow Diagramming Method (ADM) Each activity must have a unique i – j numbers, where i (the number at the tail of the arrow) is smaller than j (the number at the head of the arrow). It is recommended to have a gap between numbers (i.e., 5, 10, 15, etc.). This will allow for accommodation of missed activities. Avoid back arrows. 12

13. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 13 *IPA Activity - A A B A C B D C,D E *immediately preceding activity

14. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 14 IPA Activity - A A B A C B D C,D E 10 30 40 20 50 C D A B E

15. Arrow Diagramming Method (ADM) The dummy activity is an activity with zero duration, consumes no resources, drawn as dashed lines, and used to adjust the network diagram. When more than one arrow leave the same node and arrive at another node, dummy activities must be used. When one activity depends upon two preceding activities and another activity depends only upon one of these two preceding activities, dummy activities must be used. 15 Dummy Activities (fictitious)

16. Arrow Diagramming Method (ADM) Used to maintain unique numbering of activities. Used to complete logic, duration of “0” The use of dummy to maintain unique numbering of activities. 16 Dummy Activities (fictitious)

17. Arrow Diagramming Method (ADM) 17 4 11 4 11 10 A B A B Divide node to correct Dummy (a) Incorrect Representation (b) Correct Representation Dummy Activities (fictitious)

18. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 18 Dummy Activities (fictitious) *IPA Activity - A A B A C B,C D *immediately preceding activity

19. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 19 Dummy Activities (fictitious) IPA Activity - A A B A C B,C D 10 30 20 40 C D A B 10 30 40 20 50 C D A B Dummy Improper solution Proper solution

20. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 20 Dummy Activities (fictitious) *IPA Activity - A A B A C B D B,C E C F *immediately preceding activity

21. Arrow Diagramming Method (ADM) Draw the arrow network for the following project. 21 Dummy Activities (fictitious) IPA Activity - A A B A C B D B,C E C F 10 30 40 20 60 C E A B Dummy 1 50 Dummy 2 D F

22. Arrow Diagramming Method (ADM) Removal of Redundant Activities 22 A A A A B B B B C C Original Diagram Diagram after removal of redundant dummies (a) (b)

23. Arrow Diagramming Method (ADM) Removal of Redundant Activities 23 Original Diagram Diagram after removal of redundant dummies A A A A C C B C B B (c) (d) B E C E E E

24. Arrow Diagramming Method (ADM) Removal of Redundant Activities 24 Immediately Preceding Activity (IPA) Depends Upon Activity ----- A B ----- A A, B A B C B C A Redundant Relationship

25. Arrow Diagramming Method (ADM) Removal of Redundant Activities 25 Depends Upon Description Activity ----- ----- A A, B, C A, B, C B, C, J, M B, C, D, E, K D, E, F, G, L ----- ----- ----- ----- Site Clearing Removal of Trees Excavation for Foundations Site Grading Excavation for Utility Trenches Placing formwork & Reinforcement Installing sewer lines Pouring concrete Obtain formwork & reinforcing steel Obtain sewer lines Obtain concrete Steelworker availability A B C D E F G H J K L M

26. Arrow Diagramming Method (ADM) Removal of Redundant Activities 26 H 40 G 45 C F D 35 15 10 5 B A 20 M 25 J 30 E L K

27. NODE NETWORKS METHOD (AON) 27

28. Node Networks Method (AON) This method is also called the precedence diagram method (PDM) . The nodes represent activities and the arrows represent logical relationships among the activities. AON representation allows the overlap or lag representation on the relationship arrows connecting activities. 28

29. Node Networks Method (AON) 29 a) Independent Activities 10 A 20 B Activity number Activity name b) Dependent Activities 20 B 10 A Link Link B depends on A

30. Node Networks Method (AON) 30 30 C 10 A 20 B 40 D c) A Merge Relationship C depends on A & B D depends on C d) A Burst Relationship 20 B 30 C 40 D 10 A B depends on A C depends on B D depends on B

31. Node Networks Method (AON) 31 e) Start & Finish Dummy Activities A C B E D A Start Dummy Finish Dummy C B E D

32. Node Networks Method (AON) Draw the node network for the following project. 32 *IPA Activity - A A B A C B D C,D E *immediately preceding activity

33. Node Networks Method (AON) Draw the node network for the following project. 33 IPA Activity - A A B A C B D C,D E A E C D B

34. Node Networks Method (AON) Draw the node network for the following project. 34 *IPA Activity - A A B A C B,C D *immediately preceding activity

35. Node Networks Method (AON) Draw the node network for the following project. 35 IPA Activity - A A B A C B,C D A C D B

36. Node Networks Method (AON) Draw the node network for the following project. 36 *IPA Activity - A A B A C B D B,C E C F *immediately preceding activity

37. Node Networks Method (AON) Draw the node network for the following project. 37 IPA Activity - A A B A C B D B,C E C F A PF C D B E F

38. Node Networks Method (AON) 38 Incorrect Correct Recommendations for Proper Node Diagram Drawing

39. Node Networks Method (AON) 39 A B A B A B A B Improper Proper Recommendations for Proper Node Diagram Drawing

40. Node Networks Method (AON) 40 Improper Proper Recommendations for Proper Node Diagram Drawing

41. Node Networks Method (AON) 41 Improper Proper Recommendations for Proper Node Diagram Drawing

42. Node Networks Method (AON) 42 Improper Proper A B C A B C PS Do not start a network with more than one node Recommendations for Proper Node Diagram Drawing

43. Node Networks Method (AON) 43 Improper Proper Do not end a network with more than one node A B C A B C PF Recommendations for Proper Node Diagram Drawing

44. Lags and Leads 44

45. Lags and Leads In some situations, an activity cannot start until a certain time after the end of its Predecessor. Lag is defined as a minimum waiting period between the finish (or start) of an activity and the start (or finish) of its successor. Arrow networks cannot accommodate lags. The only solution in such networks is to treat it as a real activity with a real duration, no resources, and a $0 budget. 45

46. Lags and Leads The term lead simply means a negative lag. It is seldom used in construction. In simple language: A positive time gap (lag) means ‘‘after’’ and a negative time gap (lead) means ‘‘before.’’ 46

47. Lags and Leads Lag describes delay. It means addition of time so it is denoted by “+” sign in the network diagram. Lead always describes advancement. This means reduction in time taken so it is denoted by “-” sign in the network diagram. 47

48. Lags and Leads 48 Place Concrete 3 Strip Forms 2 3 A lag in a node network Place Concrete Strip Forms Cure Concrete A lag in an arrow network

49. Examples 49

50. AOA and AON Networks Construct an AOA and AON networks for the activities listed in Table below 50 IPA Activity - A - B A, B C C D C E D F D, E G

51. AOA and AON Networks For the network below, prepare a table showing a list of immediate predecessors and immediate successors for each of the activities. Use the i - j node notation for activities. 51 5 7 4 3 1 2 6

52. Thanks 52