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Published byJonah Walters Modified over 9 years ago
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Dependencies and Network Diagrams
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Agenda Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path
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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
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Building a Zebra Enclosure 3. Construct Zebra Enclosure 3.1 Build Fence 3.2 Review/Adjust Fence 3.3 Build Shelters 3.4 Review/Adjust Shelters 3.5 Landscape 3.6 Review/Adjust All 3.7 Zebra Enclosure Completed
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Example from Test Assembly Phase Completed Construction Phase of Zebra Enclosure 3.6 Review & Adjust All 3.1 Build Fence 3.3 Build Shelters 3.2 Review & Adjust Fence 3.4 Review & Adjust Shelters 3.5 Landscape Zebra Enclosure Completed Milestone
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Predecessors? Of 3.6? – 3.2, 3.4, 3.5 Of 3.2? – 3.1 Of 3.4? – 3.3
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Agenda Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path
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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.
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Agenda Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path
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Calculating Slack/Float What is the earliest/latest possible start of each task?
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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
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Early Start/Finish ES = latest finish of predecessors EF = (ES + duration)
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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 2 581 2 2 2 6 6 6 4 3 5 26 8 7 7 10
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Early Start/Finish Assembly Phase Completed Construction Phase of Zebra Enclosure 3.6 Review & Adjust All 5 days 3.1 Build Fence 12 days 3.2 Review & Adjust Fence 4 days 3.4 Review & Adjust Shelters 2 days 3.5 Landscape 7 days Zebra Enclosure Completed Day 1 3.3 Build Shelters 5 days 1 1 1 13 6 8 6 17 8 22
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Late Start/Finish LF = latest start of successors LS = LF - duration
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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 2 581 2 2 2 6 6 6 4 3 5 26 8 7 7 10 8 6 8 8 8 7 7 65 5 5 5 4 3 2 21
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Late Start/Finish Assembly Phase Completed Construction Phase of Zebra Enclosure 3.6 Review & Adjust All 5 days 3.1 Build Fence 12 days 3.2 Review & Adjust Fence 4 days 3.4 Review & Adjust Shelters 2 days 3.5 Landscape 7 days Zebra Enclosure Completed Day 1 3.3 Build Shelters 5 days 1 1 1 13 6 8 6 17 8 221 10 2217 13 15 17 15 13
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Agenda Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path
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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
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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 2 581 2 2 2 6 6 6 4 3 5 26 8 7 7 10 8 6 8 8 8 7 7 65 5 5 5 4 3 2 21 0 1 1 0 0 0 2 1 0
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Slack Time = LF - EF Assembly Phase Completed Construction Phase of Zebra Enclosure 3.6 Review & Adjust All 5 days 3.1 Build Fence 12 days 3.2 Review & Adjust Fence 4 days 3.4 Review & Adjust Shelters 2 days 3.5 Landscape 7 days Zebra Enclosure Completed Day 1 3.3 Build Shelters 5 days 1 1 1 13 6 8 6 17 8 221 10 2217 13 15 17 15 13 0 9 0 0 0 9
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Agenda Dependencies Milestones The Network Early/Late Start/End dates Slack/Float Critical Path
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Longest duration path in network diagram Path of tasks whose early and late dates are the same Path of tasks with zero slack
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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 2 581 2 2 2 6 6 6 4 3 5 26 8 7 7 10 8 6 8 8 8 7 7 65 5 5 5 4 3 2 21 0 1 1 0 0 0 2 1 0
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Critical Path Assembly Phase Completed Construction Phase of Zebra Enclosure 3.6 Review & Adjust All 5 days 3.1 Build Fence 12 days 3.2 Review & Adjust Fence 4 days 3.4 Review & Adjust Shelters 2 days 3.5 Landscape 7 days Zebra Enclosure Completed Day 1 3.3 Build Shelters 5 days 1 1 1 13 6 8 6 17 8 221 10 2217 13 15 17 15 13 0 9 0 0 0 9
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