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CP2730 - Chapter 4 Schedule Planning 1. Activity definition leads to the WBS Activity definition should not be so tight as to define virtually every task.

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Presentation on theme: "CP2730 - Chapter 4 Schedule Planning 1. Activity definition leads to the WBS Activity definition should not be so tight as to define virtually every task."— Presentation transcript:

1 CP Chapter 4 Schedule Planning 1

2 Activity definition leads to the WBS Activity definition should not be so tight as to define virtually every task The activity definition process goes just far enough to identify all tasks so you can create time and budget estimates Defining Activities 2

3 Activity Sequencing Some activities can run side by side Others must occur one before the other – these activities are said to have dependencies Types of dependencies: Mandatory: one task depends on another Discretionary: you can choose the sequence and/or dependency of a task(s) External: something outside affects/controls the tasks sequencing (dependency) 3

4 Logical Relationships One task can affect the start/finish time of another, it may need to be finished before another starts: Predecessor: a task that occurs before another task (on the same path) Successor: a task that occurs after another task (on the same path) 4 Task B (B is a successor to task A) Task A (A is a predecessor to task B)

5 Logical Relationships Different kinds of relationships can exist between activities: Finish- to-Start: successor cannot begin until predecessor finishes Start-to-Finish: finish of successor depends on start of predecessor Finish-to-Finish: finish of successor depends on finish of predecessor Start-to-Start: start of successor depends on start of predecessor 5

6 A network diagram models project activities and the relationships among the activities. The Precedence Diagramming Method (PDM) is a common type of network diagram (see next slide). PDM style uses boxes to represent tasks and arrows to show dependencies. Creating a Network Diagram 6

7 Other types of network diagramming include: arrow diagramming method (ADM) conditional diagramming method (CDM) critical path method (CPM) * The text mentions critical chain method (CCM), and while this is a valid type it is not discussed later in the text, but CPM (another method) is discussed later in the chapter (* referring to CCM looks like a misprint) Creating a Network Diagram 7

8 Network Diagram (PDM) Example In this example (taken from Figure 4.2 in text): Activity A is a predecessor to Activities B and D. Activity B is a predecessor to Activities C and D. In order for D to start, both A and B must be complete. In order to end the project, both C and D must be complete. BEndAC D 8 Start

9 Basic rules for PDM network diagrams: there is one start and one end box each box equates to one activity (task) arrows connect one box to another an arrow coming into a box indicates a dependency there can be more than one arrow coming out of or going into a box (indicating multiple dependencies) network diagrams are created after activity estimates are known Creating a Network Diagram 9

10 Activity Duration Estimating Along with identifying tasks (activities) and their dependencies, you need to specify (estimate) how long each task takes. Duration is how long it takes to complete a task in terms of days, hours, weeks, months, etc. – the total elapsed time. When estimating how long an activity is going to take, hours in the workday, weekends, holidays, etc. have to be considered. * See Figure

11 Duration Estimating Techniques Several techniques can be used for estimating, including: analogous: using durations from similar activities on a previous project expert judgement: using experts to create estimates – someone who can draw on past experience parametric estimating: quantitatively based where the quantity of work multiplied by the rate 11

12 Duration Estimating Techniques three-point estimates: an average of the most likely estimate, pessimistic estimate and optimistic estimate sample: ( )/3 = 11 days PERT (Program Evaluation and Review Technique): similar to three-point but use 4 of the most likely in your calcs and divide by 6 to get the average sample: ((10*4) )/6 = 10.5 days * See Figure

13 Creating The Project Schedule Schedule development is the establishment of start and finish dates for all project activities Schedule development techniques include: Mathematical analysis (critical path method) Duration compression Project management software 13

14 Critical Path Method (CPM) The Critical Path Method: the longest activity sequence path in the project controls the finish date of the project activities on path have no float (slack) time also identifies tasks that can start late (have float time) To use CPM, complete the following steps: 1.Forward Pass 2.Backward Pass 3.Float 14

15 CPM Forward Pass Use Network Diagram and working from left-to-right: 1.Calculate Early Start: Earliest date activity may begin based on any predecessors 1 st task has Early Start of 0 Use duration of activity (plus any predecessors) 2.Calculate Early Finish: Earliest date activity may finish based on Early Start Use duration of activity (plus Early Start) * See Figure 4.4 and Table

16 CPM Backward Pass Use Network Diagram and working from right-to-left: 1.Calculate Late Finish: Latest date activity may complete without impacting end date Late Finish of last task(s) is the project finish date Subtract duration from Late Finish to get Late Finish of its predecessor 2.Calculate Late Start: Latest date activity may be started without impacting end date Late Start of 1 st task is 0 Subtract duration from Late Finish to get Late Start Late Start of one task becomes Late Finish for its predecessor * See Figure 4.4 and Table

17 CPM Float Using the Forward Pass and/or Backward Pass information, calculate Float by either: subtracting Early Start from Late Start subtracting Early Finish from Late Finish * NOTE: If done correctly, using either calculation will give the same result, so you can verify correctness by doing both. * See Figure 4.4 and Table 4.3 The Critical Path includes all tasks that do not have Float (slack) time. 17

18 Duration Compression Duration Compression can be used when total project time is calculated to be greater than expected completion time Compression techniques include: Crashing: You add resources to an activity so as to reduce its duration You cannot crash critical path activities Might result in a new critical path May have an economic impact on project (can be costly to do) Fast Track: Do tasks in parallel (that would normally be done in sequence) Involves a lot of risk, so must communicate this to stakeholders 18

19 Project Management Software Project Management Software (such as MS Project) can be very useful in scheduling, WBS, etc. and in communicating this info. Various diagrams and charts can be created and used (i.e. Gantt, etc.) 19

20 Project Management Software Milestones are key events in a project: which should be identified/defined which often involve major deliverables whose dates are very important that can be documented using a milestone chart (* see Table 4.4) Gantt charts can also show milestones (* see Figure 4.5 for a sample Gantt) 20

21 Project Management Software The schedule baseline is the: final approved version of schedule (at the start of project) must be approved by stakeholders can be used throughout project to measure progress should only be changed if (absolutely) necessary * See page 106 (Real World Scenario) for discussion of some of the Chaptal Wineries project scheduling, etc. issues 21


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