1. Project Management module
Network and Critical Path Analysis
William Wright, Ashcroft International Business School
International Business & Strategy
Project Management

2. Network Analysis/Critical Path Analysis
Network Analysis is used by project managers to plan and allocate resources to minimise total project duration and project costs
Critical Path Analysis is a complementary technique to identify tasks which must be executed on time in order for the project to complete on schedule
There are five basic steps in network analysis:
Identify all the activities that need to be undertaken as part of the project
Estimate the time it will take to complete each activity
Identify the order in which the activities must be completed
Construct a network diagram
Calculate total project duration
Project Management

3. Basic planning terminology
Activity
A specific task or set of tasks that are required by the project, use up resources, and take time to complete.
Network
The combination of all activities that define the project and the sequence of relationships between them.
Milestone
A zero duration activity (task) which does not involve any work but which is nonetheless important as a key achievement e.g. Contract Award, Project Completion.
Critical
Activities, events, or paths which, if delayed, will delay the completion of the project. A project’s critical path is understood to mean that sequence of critical (slowest) activities that connect the project’s start activity to its finish activity. *

4. Project planning fundamentals
Any project can be broken down into a set of tasks
Example project "Making mug of tea"
1. fill kettle
2. boil kettle
3. find mug
4. put teabag in mug
5. fill mug with boiling water
6. after a short period, remove teabag
7. add milk and/or sugar as required.
Project Management

5. Project planning fundamentals
… in a simple diagrammatic form
Project Management

6. Project planning fundamentals
… but what happens in practice?
… you can undertake other tasks whilst the kettle is boiling
Project Management

7. Constructing a Network Diagram - notation
More than one activity can follow another: B and C can start once A is finished.
More than one activity can finish before another can start: C may only start once A and B are both complete. B A C A C B
Activities running in parallel are the norm in network diagrams: this reflects the reality of how projects actually proceed in practice.
Project Management

8. A simple house building example
Project Management

9. House building example – durations added
Project Management

10. …and now with start and finish dates calculated
Project start
date known
Project end
date calculated
The critical path is identified (marked in red) … …and non-critical tasks have float (i.e. some delay permissible)
Project Management

11. The same project as a Gantt (bar) chart
Project Management

12. Network Analysis – recap of main points
A network chart will always give valuable insight into how the project will be executed.
Project staff will be able to plan ahead using this information: they will have the planned start and finish times for each activity (usually converted into dates)
Critical tasks will receive the close attention they deserve (if they slip, the entire project will slip - unless the delay can be recovered)
The amount of float on non-critical tasks will be calculated - also very useful to know
This information will aid the development of project controls
Overall, the project will stand a greater chance of finishing on schedule *
Project Management

13. Network Analysis – some good news
Software packages such as Microsoft Project will perform all the EST and LFT calculations (and many others) instantly. They will allow you to change the network diagram in any way - and recalculate everything instantly.
The software is scalable and can deal with hundreds or even thousands of activities.
Costs and resources can be added to generate financial budgets.
Reports and charts can be printed in a professional format.
But unless you need an appreciation of the underlying theory, to progress with the software...
Project Management