prj566 project planning and management lecture: dependencies and network diagrams
TRANSCRIPT
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
1.1Measure Room
1.2Choose colors
1.3 Create Materials List
1.4 Create Estimate Sheet
1.5Review with client
2 Purchase Materials
3.1 Move Furniture
3.2 Wash Walls 3.3 Cover
Floors
4 Paint Room
4 Paint Room
5.1 Clean up
5.2 Remove Floor Covers
Network Diagram = Gantt Chart
1.1
1.2
1.3 1.4 1.5
2
3.1 3.2 3.3
4
5.1 5.2
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
1.1 1
1.2 2
1.3 1
1.4 3
1.5 1
2.1 2
2.2 1
2.3 1
2.4 2
5 81
2
2
2
6
6
6
3
2
4
1 5
7
6
6
9
Late Start/Finish
• LF = earliest start of successors - 1
• LS = (LF - duration) + 1
Late Start/Finish
1.1 1
1.2 2
1.3 1
1.4 3
1.5 1
2.1 2
2.2 1
2.3 1
2.4 2
5 81
2
2
2
6
6
6
3
2
4
1 5
7
6
6
9
98
6
7
7
7
7
755
4
4
4
4
3
2
11
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
1.1 1
1.2 2
1.3 1
1.4 3
1.5 1
2.1 2
2.2 1
2.3 1
2.4 2
5 81
2
2
2
6
6
6
3
2
4
1 5
7
6
6
9
98
6
7
7
7
7
755
4
4
4
4
3
2
11
0
1
2
0
0
0
1
1
0
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
1.1 1
1.2 2
1.3 1
1.4 3
1.5 1
2.1 2
2.2 1
2.3 1
2.4 2
5 81
2
2
2
6
6
6
3
2
4
1 5
7
6
6
9
98
6
7
7
7
7
755
4
4
4
4
3
2
11
0
1
2
0
0
0
1
1
0
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!
• Let’s look at an example
Critical Path
1.1 1
1.2 2
1.3 1
1.4 3
1.5 1
2.1 2
2.2 1
2.3 1
2.4 2
3.1 1 3.2 2 4 22.4 2
Critical Path