Floats in the Ao A network Project management

Floats in the Ao. A network Project management (lecture)

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

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

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

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

Calculating free float • The float possessed by an activity which, if used, will not change the float in leater activities. • Free floatj = ESTj+1 – EFTj = EEThead – EETtail - D Free float = =5– 0– 5=0 5 1 2 5 11 Free float = 23 – 5 – 12 = 6 12 0 a c 0 15 8 b 3 15 15 d 4 23 23

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. 30 • Negative float is a type of the Total Float. 1 0 10 ? a 2 ? 10 ? c 3 ? ?

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. 15 • Negative float is a type of the Total Float. 1 0 10 -5 a Total float: -5 2 10 10 5 c Total float: -5 3 20 15

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

Readings • Lockyer – Gordon (2005) Chapter 13

Thanks for the attention!

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