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Floats in the AoA network Project management (lecture)

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Presentation on theme: "Floats in the AoA network Project management (lecture)"— Presentation transcript:

1 Floats in the AoA network Project management (lecture)

2 Activity and event times Activity times: – EST – LST – EFT – LFT Event times: – EET – LET

3 Float Time available for an activity or path in addition to its duration. It can be positive or negative It is a property of activities (and available only at given activities) In case of more succeeding activities, the minimum have to be taken. Types of float: – Total float – Free float

4 Total float The total float possessed by an activity. Calculation for activity j: Total float j = LFT j – EFT j Identify the activity possessing float below, and calculate the total float. 1 0 ? 2 ? ? a 12 4 ? 35 c 10 3 ? ? b 15 d 8

5 Total float The total float possessed by an activity. Calculation for activity j: Total float j = LFT j – EFT j = LFT j – (EST j + D j ) Identify the activities possessing float below, and calculate the total float for each. 1 0 0 2 5 11 a 5 4 23 c 12 3 15 b d 8 Total float = 23 – (5+12) = 6 Total float = = 11 – (0+5) = 6

6 Calculating free float The float possessed by an activity which, if used, will not change the float in leater activities. Free float j = EST j+1 – EFT j = EET head – EET tail - D 1 0 0 2 5 11 a 5 4 23 c 12 3 15 b d 8 Free float = 23 – 5 – 12 = 6 Free float = = 5 – 0 – 5 = 0

7 Negative float If the target time (deadline) for the project (or for a part of the project) is grater than TPT, than the float will appear on the critical path or even on some other paths. Negative float = the time by which activities on the path or paths concerned must be reduced if the TPT is to be met. Negative float is a type of the Total Float. 1 0 ? 2 ? ? a 10 3 ? ? c 30

8 Negative float If the tartget time (deadline) for the project (or for a part of the project) is grater than TPT, than the float will appear on the critical path or even on some other paths. Nagative float = the time by which activities on the path or paths concerned must be reduced if the TPT is to be met. Negative float is a type of the Total Float. 1 0 -5 2 10 5 a 3 20 15 c 10 15 Total float: -5

9 Slack Refers to events and not to activities. Slack = LET - EET Slack: 0 1 0 0 2 5 11 a 5 4 23 c 12 3 15 b d 8 Total float = 23 – (5+12) = 6 Total float = = 11 – (0+5) = 6 Slack: 0 Slack: 6

10 Readings Lockyer – Gordon (2005) Chapter 13

11 Thanks for the attention!

12 1 0 0 2 7 11 a 7 4 23 c 10 3 15 b d 8


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