Project networks
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The document discusses two approaches to project networks: activity-on-arrow (AOA) and activity-on-node (AON) methodologies, detailing how activities and their relationships are represented visually. It explains key concepts such as predecessor and successor activities, critical paths, and the rules governing project networks, including the importance of identifying unique activity identifiers. Additionally, it introduces time-related properties of tasks such as early start, late finish, and slack.
Project networks
- 1. Project Networks Two Approaches • Activity-on-Arrow (AOA): Uses an arrow to depict an activity • Activity-on-Node (AON): Uses a node to depict an activity
- 2. Activity on Arrow (AOR) Activities are shown by Arrow Length of Arrow may show relative time to complete tasks Nodes show where activities end and begin in sequence. The starting node for an activity is the activity’s “i-node,” the ending node is the “j-node. Task A Task B Task C Task D Each project has a starting “i-node” and ending “j- node”
- 3. Activity on Arrow (AOR) Task A Task B Task C Task D
- 4. Activity on Node (AON) Start Task A Task B Task E Task C Task D End
- 5. Activity on Node (AON) Activities are show in nodes or boxes Start Task A Task B Task E Task C Task D End Project Has a Start and an End Task C is a predecessor to Task E and a successor to Task A Arrow show dependencies. Task D can’t start until both Task A and B have completed
- 7. • Networks typically flow from left to right. • An activity cannot begin until all of its preceding activities are complete. • Arrows indicate precedence and can cross over each other. • Identify each activity with a unique identifier; this identifier must increment (1.2.3, A,B,C, etc.) as the network proceeds. • Looping is not allowed. • Conditional statements are not allowed. • Use start and stop nodes. Project Networks Rules
- 8. • Terminology: A C B D Constructing a Project Network • Parallel (concurrent) activities: Activities that can occur independently and, if desired, at the same time. • Merge activity: an activity that has two or more preceding activities on which it depends. • Activity: an element of the project that requires time. Time
- 9. • Terminology B D A C Constructing a Project Network (cont’d) • Burst activity: an activity that has more than one activity immediately following it (more than one dependency arrow flowing from it). • Milestone: a point in time when an activity is started or completed. It does not consume time. Q
- 12. = Early Start ES Time-Related Task Properties = Early FinishEF = Late StartLS = Late Finish LF = Slack or FloatSL = DurationDR A Task
- 14. A 4 Project Networks C 3 B 8 D 2 E 3 F 10 Critical Path ES ID EF SL LS DR LF
- 15. Longest Path through the project network (not the path with the most number of tasks, but the one that takes the longest). = Any delay of a task on the critical path will delay the entire project. PM needs to watch = Tasks with zero slack= Critical Path
- 16. A 4 Project Networks C 3 B 8 D 2 E 3 F 10 A-B-D-F 4+8+2+10 = 24 A-C-E-F 4+3+3+10 = 20 ES ID EF SL LS DR LF
- 17. A 4 Project Networks C 3 B 8 D 2 E 3 F 10 A-B-D-F 4+8+2+10 = 24 A-C-E-F 4+3+3+10 = 20 ES ID EF SL LS DR LF