Lecture 3 - Time Planning

Question 1

Draw out the breakdown of the time planning years:

Answer 1

…

Question 2

Define a ‘work package’:

Answer 2

A work package is a subset of a project that:

• Can be assigned to specific resources (people, machines etc).
• Produces a deliverable within the project.

Question 3

What should work packages be?

Answer 3

Small enough:

• Require the same resources throughout.
• Keeping track of WPs give a good view of the project’s overall status.

Large enough:

• Lead to a verifiable outcome.
• Form independent units of work with distinct start times + resources.

Rule of thumb: typical WPs last several days to weeks.

Question 4

There are three ways in which a process overview can be broken down; what are these?

Answer 4

1. Activity breakdown.
2. Physical breakdown.
3. Functional breakdown.

The highest level in the each breakdown is the most different to all others.

Question 5

In the activity breakdown, what are the tasks broken down into?

Answer 5

• Major activity groups (and activity sub-groups).
• Individual work packages.

The number of levels of the breakdown depends on the project complexity.

Question 6

In the functional breakdown, what are the tasks broken down into?

Answer 6

• Major functional areas / departmental units (and activity sub-groups).
• Individual work packages.

The number of levels of the breakdown depends on the project complexity.

Question 7

In the physical breakdown, what are the tasks broken down into?

Answer 7

• Major product modules (and activity sub-groups).
• Individual work packages.

The number of levels of the breakdown depends on the project complexity.

Question 8

When should you employ the functional breakdown?

Answer 8

• When the functional organisation takes place in a functional organisation (i.e. when the team comes from different departments).
• Project manager has little authority over team members in functional units.

Question 9

When should you employ the physical breakdown?

Answer 9

• Project decomposes naturally into independent modules (construction, software, physical products).

Question 10

When should you employ the activity breakdown?

Answer 10

• Project outcome is a service (e.g. IT development process).

Question 11

What is meant by ‘task dependency?

Answer 11

The start/completion time of task B depends on the start/completion time of task A.

There can be multiple dependencies.

Question 12

What 5 things are mentioned in the task description of the CPA?

Answer 12

1. EST: Earliest start time.
   - Start time if all predecessor tasks are started ASAP.
2. LST: Latest start time.
   - If started afterwards, project completion will be delayed.
3. Activity description.
4. Duration of task.
5. Total float of activity.
   - Difference between EST and LST.
   - Maximum time that task can be delayed without affecting project duration.
   - If total float is zero, then the activity lies on the CRITICAL PATH.

Question 13

What is the purpose of the forward pass in the CPA?

Answer 13

To determine the earliest start times of the tasks.

• Maximum EST of predecessors + duration.

Question 14

What is the purpose of the backward pass in the CPA?

Answer 14

To determine the latest start times of the tasks.

• Minimum LST of predecessors - duration.

Question 15

Is there always a critical path in CPA?

Answer 15

Yes.

Question 16

Can there be several critical paths?

Answer 16

Yes.

Question 17

If there is a critical task, does it have to lie on the critical path?

Answer 17

Yes.

Question 18

What method is used to visualise project tasks over time?

Answer 18

Gantt charts.

• Tasks lie on the ordinate; timeline on the abscissa.
• Tasks are bars; milestones as diamonds; precedences as arrows.

Question 19

Name two PM softwares which plot Gantt charts?

Answer 19

1. Microsoft Project.

2. Oracle Primavera.

Question 20

What are the advantages of CPA + Gantt charts?

Answer 20

• Determines (most likely) project completion date.
• “What-if” analysis possible.
• Visualises dependencies and tasks that can be run in parallel.
• Helps to determine (non-) critical tasks and paths.
• Good communication tool (team, client, other stakeholders).

Question 21

What are the disadvantages of CPA and Gantt charts?

Answer 21

• Task durations are often difficult to estimate.
• Does not handle resource constraints.
• May result in excessive multi-tasking.
• Can become complex for large projects.

Question 22

What are the 5 problems with CPA + Gantt charts?

Answer 22

1. Estimates for task durations include large safety margins.
2. Parkinson’s Law (tasks expand to fill the time available).
3. Student syndrome (margins are wasted at the start of the task).
4. Murphy’s Law (the unexpected will happen, for sure).
5. CPA encourages multitasking (time is lost when switching between tasks; task priorities often unclear to team members).

Question 23

How are the 5 issues related to the CPA + Gantt charts managed?

Answer 23

1. Median task durations are used and no safety added to task durations which removes the stigma of late finish.
2. Determine the project’s critical chain (sequence of precedence and resource-dependent elements that prevent project from being completed in a shorter time given the available resources; in absence of resource constraints, critical path is equal to the critical chain).
3. Include buffers to protect critical chain:
   - 1. Project buffer: inserted at the end of the project network.
   - 2. Feeding buffer: inserted at the end of the task paths feeding critical chain; protects critical chain from being delayed by other paths.
   - 3. Resource buffer: inserted when a non-critical task precedes a critical one and both share a common resource.
   SUGGESTED BUFFER SIZE IS 50% OF INVOLVED TASKS.
4. Project control:
   - Traditional approach (due dates, % task completion).
   - CC/BM (monitor state of buffer and the rate at which they deplete).