## May 4, 2012

### PM0011 [Project Planning & Scheduling] Set2 Q3

Question 3: Draw a network diagram and answer the questions below:

a) Activity 1 can start immediately and has an estimated duration of 4 weeks.
b) Activity 2 can start after activity 01 is completed and has an estimated duration of 5 weeks
c) Activity 03 can start after activity 01 is completed and has an estimated duration of 5 weeks
d) Activity 04 can start after activity 02 is completed and has an estimated duration of 8 weeks
e) Activity 05 can start after activity 04 is completed and after activity 03 is completed this activity takes 5 weeks.
1) Calculate the start and end time of the all the activities in the network diagram.
2) Calculate the slack value of the task.
Answer:

A project network diagram, also known as a precedence diagram, is a handmade or software-created diagram that shows the relationships in time and dependency of steps needed to complete a project. The diagram clarifies which steps can precede others, which steps must succeed others, and which can occur simultaneously, as well as other project constraints. It also shows when lead time allows beginning one task before another is complete as well as when lag time is needed after a step has been completed before a succeeding step can commence. A project network diagram is helpful in computing start and end dates, apportioning resources and personnel, and analyzing scheduling choices.

There are a variety of ways to create a graphical representation of a project network diagram. It is common to use left to right progression to show change from earlier time, at the left, to later time, at the right. It is also common to prepare for creating a project network diagram by preparing a chart of activities, roughly in chronological order, with verbal notes about dependencies.

Precedence Diagramming Method (PDM):
It is a method for constructing project schedule network diagram that has rectangular boxes, depicting nodes and arrows connecting the boxes, depicting the logical relationship between the activities. This technique is also called Activity on Node (AON).

To make our diagramming easier, we need to create a table of all the activities, their predecessors, and their durations.

 Activity Predecessor Duration Start - - 1 Start 4 weeks 2 1 5 weeks 3 1 5 weeks 4 2 8 weeks 5 3 and 4 5 weeks

1) Calculation of start and end time of all the activities in the network diagram.
Sum the duration of each activity on the path.

Start - 1 - 2 - 3 - 4 - 5 End is 4 + 5 +5 + 8 + 5 = 27 weeks

2) Calculation of the slack value of the task.

Tasks possessing a difference among early and late dates are said to possess slack (or float) and such tasks are known as non-critical tasks. To calculate slack values for each task, use the formula:
TS = LF-ES Duration