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 2 1 4 3 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. 2 ? 10 12 1 ? 4 ? 35 c a 15 3 ? 8 b d

5. Total float 2 1 4 3 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 2 5
Total float = 23 – (5+12) = 6 12 5 11 c a 1 4 23 15 8 23 b 3 15 d 15

6. 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 2 5
Free float = 23 – 5 – 12 = 6 12 5 11 c a 1 4 23 15 8 23 b 3 15 d 15

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. 30 1 ? 2 ? 3 ? 10 10 a c

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. 15 1 -5 2 10 5 3 20 15 10 10 a c
Total float: -5
Total float: -5

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

10. Readings
Lockyer – Gordon (2005) Chapter 13

11. Thanks for the attention!

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