PRJ566 Project Planning and Management Lecture: Dependencies and Network Diagrams

Agenda Dependencies Milestones The Network –Early/Late Start/End dates –Slack/Float –Critical Path

To Create a Plan You Need… Work Breakdown Structure Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path

Task Dependencies Task A is said to be dependent on task B if task B must precede task A (task B must be finished before task A can start) Task B is called a predecessor of task A Task A can have many predecessors Only immediate predecessors are referred to as predecessors

Agenda Dependencies Milestones The Network –Early/Late Start/End dates –Slack/Float –Critical Path

Milestone A task with zero time allocated to it. It is used as a marker; documentation. It is not assigned to anyone. Tasks can be dependent on milestones.

Agenda Dependencies Milestones The Network –Early/Late Start/End dates –Slack/Float –Critical Path

Network Diagram A pictorial representation of the sequence in which the project work can be done Shows the relationships (dependencies!) between tasks MS Project creates network diagrams for you (=Gantt chart in MS Project)

Network Diagram What order do 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

Why are they important? You can plan more effectively--you can see the relationship between activities Easier to reschedule--you can see impact of changes Allows you to monitor and control the project--compare it against baseline

Identifying Dependencies Dependencies are caused by constraints: Technical constraints –Discretionary –Best practices –Logical –Unique situations

Identifying Dependencies Dependencies are caused by constraints: Management Inter-Project

Calculating Slack/Float What is the earliest/latest possible start of each task?

Late and Early Start/Finish Early start/finish--earliest possible time that a task can start/finish without causing delay Late start/finish--latest possible time that a task can start/finish without causing delay

Early Start/Finish ES = latest finish of predecessors + 1 EF = (ES + duration) - 1

Early Start/Finish

Late Start/Finish LF = earliest start of successors - 1 LS = (LF - duration) + 1

Late Start/Finish

Agenda Dependencies Milestones The Network –Early/Late Start/End dates –Slack/Float –Critical Path

Slack/Float time The delay (in units of time) that could be tolerated in starting or completion time of a task without causing a delay in the project. Slack time for a task = LF - EF

Slack Time = LF - EF

Agenda Dependencies Milestones The Network –Early/Late Start/End dates –Slack/Float –Critical Path

Critical Path Longest duration path in network diagram Sequence of tasks whose early and late dates are the same Sequence of tasks with zero slack

Critical Path

Why care about Critical Path? Tasks on this path need to be on time! If you know what they are you can track them! You can compress, adjust for maximum benefit

Critical Path MS Project automates this! Lets look at an example

Critical Path

Critical Path