Floats in the AoA network

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 floatj LFTj EFTj
• Identify the activity possessing float below, and
  calculate the total float.

10
12
c
a
15
8
b
d
5
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 (05) 6
Total float 23 (512) 6
5
2
12
5
11
c
a
0
23
1
4
15
8
0
23
15
b
d
3
15
6
Calculating free float

• The float possessed by an activity which, if
  used, will not change the float in leater
  activities.
• Free floatj ESTj1 EFTj EEThead EETtail -
  D

Free float 5 0 5 0
Free float 23 5 12 6
5
2
12
5
11
c
a
0
23
1
4
15
8
0
23
15
b
d
3
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
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
10
10
a
c
Total float -5
Total float -5
9
Slack

• Refers to events and not to activities.
• Slack LET - EET

Slack 6
Total float 11 (05) 6
Total float 23 (512) 6
5
2
12
5
11
c
a
0
23
1
4
15
8
0
23
15
b
d
3
Slack 0
Slack 0
15
Slack 0
10
Readings

• Lockyer Gordon (2005) Chapter 13

11
Thanks for the attention!
12
7
2
10
7
11
c
a
0
23
1
4
15
8
0
23
15
b
d
3
15