PRJ566 Project Planning & Management Dependencies, Network Diagrams & Critical Path

Agenda  Where are we?  Network Diagrams  Critical Path

Where are we?  Identified work breakdown structure (WBS) – activities and tasks  Estimated tasks  Assigned resources  Assigned dependencies

Agenda  Where are we?  Network Diagrams  Critical Path

Network Diagram  A pictorial representation of the sequence in which the project work can be done  Shows the relationships (dependencies) between tasks

Network Diagram  What order to I do these tasks in?

Network Diagram 1.1 Measure Room 1.2 Choose colors 1.3 Create Materials List 1.4 Create Estimate Sheet 1.5 Review with client 2 Purchase Materials 3.1 Move Furniture 3.2 Wash Walls 3.3 Cover Floors 4 Paint Room 5.1 Clean up 5.2 Remove Floor Covers

Network Diagram = Gantt Chart

Agenda  Where are we?  Network Diagrams  Critical Path

Critical Path  A Network Diagram is a tool for identifying all the possible paths through a project. The paths are dictated by the dependencies.  To determine critical path in a network diagram, identify all the possible paths through the network diagram and add up the durations of the activities that lie along those paths.  The path with the longest duration time is the critical path.

Critical Path  Given a list of tasks and dependencies as shown below, a network diagram can be constructed. Task IDDescriptionDurationPredec essor 0 Start0None 1 Find Client3 days0 2 Find System2 days0 3 Gather Requirements6 days1,2 4 Create Use Case Diagram2 days3 5 Create Use Case Descriptions5 days3 6 Review with User1 day1,4

Network Diagram 0 Start 2 Find System 2 1 Find Client 3 Gather Requirements 6 4 Create Use Case Diagram 2 6 Review With User 1 5 Create Use Case Descriptions 5

Slack/Float time  Need to understand the slack time of an activity.  Slack time: The difference between the late finish and early finish of an activity.

Network Diagram 0 Start 2 Find System 2 1 Find Client 3 Gather Requirements 6 4 Create Use Case Diagram 2 6 Review With User 1 5 Create Use Case Descriptions 5 If task 1 above takes 3 days and task 2 takes 2 days, then there is 1 day of slack (free slack).

Calculating Critical Path  To calculate critical path: Total the durations of every path. Largest value is the critical path.

Critical Path d duration slack

Calculating Critical Path Task/ActivityDurationsTotal Critical Path!

Critical Path Task 1.2 can slip by 1 day; Task 1.3 can slip by 2 days Task 2.2 can slip by 1 day; Task 2.3 can slip by 1 day duration slack

Critical Path  Fortunately MSProject automatically calculates the Critical Path. Once you know which tasks are on the Critical Path, you can track these tasks very closely.  Once you create your Gantt Chart in MSProject, click on Format, Gantt Chart Wizard and select Critical Path and then finish. MSProject formats your project plan to show the Critical Path in Gantt Chart view.  The Critical Path is automatically calculated!

Critical Path  Longest duration path  Sequence of tasks whose early and late dates are the same  Sequence of tasks with zero slack  Drives the completion date of the project

Critical Path  The Critical Path tells you what tasks are critical.  In other words, if you change the duration or start and end date of the task on the critical path, it will affect the completion date.

Critical Path Sample – Gantt Chart