Background;

1. A precedence network diagram must be constructed with careful thought to ensure that it shows as accurately as possible the logical relationships and interdependencies of each task or activity with all the others in the project. Another great strength of critical path networks (whether arrow diagrams or precedence diagrams) is that they allow priorities to be quantified, based on analysing all the task duration estimates.

2. Those tasks that cannot be delayed without endangering project completion on time are identified as critical tasks, and all other tasks can be ranked according to their degree of criticality. An activity in precedence notation is shown as follows with a line either side linking this box from a preceding activity (on the left) and to a following activity (on the right); (AVA30001 Lecture Notes reference paragraph 5.3):

Earliest Start	Activity Duration	Earliest Finish
Activity ID number and description
Latest Start	Total Slack / Float	Latest Finish

Notes: (i) Total Slack / Float = Latest Finish Earliest Finish; or Latest Start Earliest Start. (ii) Tasks / activities with a total slack / float of 0 (zero) need to be completed on-time to enable the project to be completed on-time. Therefore, they are critical tasks / activities, and probably Milestones, and together form the Critical Path (Aviation Project Management, Flouris & Lock 2008, pages 118 and 119).

QUESTIONS:

1. Using the precedence notation box outlined above and the table of information presented below:

(i) Prepare a (free-hand) diagram of a project precedence network diagram;

(ii) Calculate the scheduling times and total slack/float for each activity;

(iii) Show the total duration of the project; and

(iv) Identify the critical tasks as Project Milestones and join them to show the Critical Path.

Using this table:

Task	Time (days)	Immediate Predecessors or Independencies
A	24	-
B	18	-
C	30	A,B
D	8	-
E	30	C
F	14	D
G	31	E,F
H	36	G
		Note: The (-) against tasks A, B and D means that these tasks can all commence at the same time after a start node.