(03) Developing the baseline network plan

Question 1

What is a Project Network Diagram?

Answer 1

A flow chart that graphically depicts the sequence, interdependencies and start and finish times of the project activities.

Question 2

How does a Project Network Diagram work?

Answer 2

• Networks typically flow from left to right.
• Arrows indicate precedence and flow.
• An activity cannot begin until all of its preceding activities are complete.
• Identify each activity with a unique number.
  - This number must be greater than its predecessors.
• Looping is not allowed.
• Conditional statements are not allowed.
• Use common start and stop nodes.

    Every activity on the network diagram must be completed for the project to finish.

Question 3

What are the Benefits of a Project Network Diagram?

Answer 3

• Provides the basis for scheduling labour and equipment.
• Enhances communication among project participants.
• Provides an estimate of the project duration.
• Provides a basis for budgeting cash flow.
• Identifies the critical activities.
• Help managers get and stay on plan.

Question 4

What is the terminology used (when Constructing a Project Diagram).

Answer 4

• Activity (or task).
• Path.
• Critical Path.

Question 5

What is an activity (or task)?

Answer 5

An element of the project that requires time – e.g., A, B, C, D, etc.

Question 6

What is a Path?

Answer 6

A sequence of connected, dependent activities.

Question 7

What is a Critical Path?

Answer 7

The longest path through the network that allows for the completion of all project-related activities.

Question 8

What is dependency?

Answer 8

Dependency relates to the sequencing of project activities.

Question 9

What are the different types of dependencies?

Answer 9

• Mandatory Dependencies (Hard Logic).
• Discretionary Dependencies (Soft Logic).
• External Dependencies.

    We must understand the type of dependencies required for each activity on our project.

Question 10

What is a successor?

Answer 10

An activity that is done directly after another activity.

Question 11

What are Mandatory Dependencies (Hard Logic)?

Answer 11

Inherent in the nature of the work itself – e.g., scrape off old paint, then apply primer, then paint the house.

Question 12

What are Discretionary Dependencies (Soft Logic)?

Answer 12

Defined by the project team - e.g., paint room 1 first and then paint room 2.

Question 13

What are External Dependencies?

Answer 13

Involve relationships between project and non-project activities – e.g., a shared hardware platform ordered by another department.

Question 14

What is a predecessor?

Answer 14

An activity that is done directly before another activity.

Question 15

What are the different types of dependency relationships?

Answer 15

• Finish-to-start relationship.
• Start-to-start relationship.
• Finish-to-finish relationship.
• Start-to-finish relationship.

Question 16

What is a Finish-to-start relationship?

Answer 16

The subsequent activity cannot start until the preceding activity is finished.
- E.g. car manufacturing: painting can’t begin until the welding is finished.

Question 17

What is a Start-to-start relationship?

Answer 17

The subsequent activity can start AFTER the preceding activity has started.
- E.g. trenching 1km and then laying the pipe while continuing the trenching activity for the next kilometre.

Question 18

What is a Finish-to-finish relationship?

Answer 18

The finish of the subsequent activity depends on the finish of the preceding activity.
- E.g. testing the prototype can start while it is still developed, but has to finish after the prototype has been fully developed.

Question 19

What is a Start-to-finish relationship?

Answer 19

The finish of the subsequent activity depends on the start of the preceding activity.
- E.g. the documentation of a system cannot finish before the testing has started.

Question 20

What is the importance of Project Network Diagram?

Answer 20

• Drawing the project network diagram places the activities in the right sequence, but…
• We need to compute the start and finish times of the activities.

Question 21

What are the two complementary approaches (of Project Network Diagrams?)

Answer 21

• Forward pass → earliest times

- Backward pass → latest times

Question 22

What three questions do you need to answer (for forward pass computation?)

Answer 22

1. How soon can the activity start?
   - (early start – ES).
2. How soon can the activity finish?
   - (early finish – EF).
3. How soon the project can be finished?
   - (expected time – TE).

Question 23

What three things do you need to remember (for forward pass computation?)

Answer 23

1. Add activity times along each path in the network.
   - (ES + duration = EF).
2. Carry the EF to the next activity, where it becomes ES, unless..
3. The successor is a merge activity. If so..
   - Select the largest EF of all its immediate predecessors.

Question 24

What four questions do you need to answer (for backward pass computation?)

Answer 24

1. How late can the activity start?
   - (late start – LS).
2. How late can the activity finish?
   - (late finish – LF).
3. Which activities represent the critical path (CP)?
4. How long can the activity be delayed?
   - (slack or float – SL).

Question 25

What three things do you need to remember (for backward pass computation?)

Answer 25

1. Subtract activity times along each path starting with the project end activity.
   - (LF – duration = LS).
2. Carry the LS to the next predecessor to establish its LF, unless…
3. The next predecessor is a burst activity. If so..
   - Select the smallest LS of all its immediate successors to establish its LF.

Question 26

What is slack (or float)?

Answer 26

The amount of time an activity can be delayed after the start of a longer parallel activity or activities.

Question 27

What is total slack?

Answer 27

The amount of time an activity can be delayed without delaying the entire project.

Question 28

What is the formula for Slack?

Answer 28

Slack = (LS - ES) or (LF - EF).

Question 29

What is Critical Path?

Answer 29

• The critical path shows the shortest time in which a project can be completed.
• The series of activities that determine the earliest time by which the project can be completed.
• The longest path through the network diagram and has the least amount of slack (or float).
• The path containing the critical task is what is driving the completion date for the project.

Question 30

What is the critical path analysis?

Answer 30

A network diagramming technique used to predict total project duration.

Question 31

What things should you consider about Critical Path?

Answer 31

• If one or more of the activities on the critical path takes longer than planned, the whole project schedule will slip.
• It is possible to have two or more critical paths in a project.
• A critical path on a project can change as the project progresses.

Question 32

Why is slack so important for the project manager?

Answer 32

• Slack allows some flexibility in scheduling, this may relieve pressure on resources that may be deployed elsewhere.
• Slack can be used without affecting the overall project completion time.

Question 33

How does the critical path help the project manager?

Answer 33

• The critical path enables the project manager to calculate the overall time of the project.
• All activities on the critical path must be completed on time.

Question 34

What do you need before you try to develop a schedule for your project?

Answer 34

• Scope definition.
• Work breakdown structure with work packages.
• Prerequisite logic (hard logic, soft logic, predecessor, successor).
• Input from the customer about milestones and expected project completion.