ISQM 410 – Project Management

1. ISQM 410 – Project Management Chapter 6 – Developing the Project Plan

2. Developing the Project Plan • Developing the Project Network • Tool for planning, scheduling & monitoring • Developed from the WBS • Illustrates: • Activities to be completed • Sequence of activities • Interdependencies • Start & finish times • Longest path through the network (critical path) • Why develop a project network? • Provides a basis for scheduling labor & equipment • Enhances communication re. Cost, schedule, & performance • Provides start/finish times and when delays can occur • Basis for budgeting the cash flow • Identifies critical activities (can’t be delayed) • Highlights activities for change if compressed deadline

3. Developing the Project Plan • Work Package > Network • Network – flow diagram of sequence, interrelationships, & dependencies of all activities required to complete the project • Activity – element in the project that consumes time (work or waiting) • Build network using nodes (boxes) and arrows (lines) – node = activity; arrow = dependency & project flow • Work package – definite start/end points, specific resources, technical specifications, & cost estimates • Network activity can have 1 or more work packages

4. Developing the Project Plan • Constructing a Project Network • Terminology • Activity – element of the project that requires times; may or may not require resources; activity descriptions use verb/non format (ex., develop product specifications) • Merge activity – activity with more that one activity immediately preceding it • Parallel activity – activities that can take place at the same time; may not occur simultaneously • Path – sequence of connected, dependent activities • Critical path – longest pat thru the network; if activity on the path is delayed, the entire project is delayed • Event – point in time when an activity is started or completed; does not consume time • Burst activity – activity that has more than one activity immediately following it

5. Developing the Project Plan • Rules for Developing Project Networks • Networks flow from left to right • An activity cannot begin until al preceding connected activities have been completed • Arrows indicate precedence & flow; arrows can cross over each other • Each activity should have a unique identification number (no., letter, combination) • Activity ID No. must be larger than that of any preceding activities • Looping is not allowed (e.g., recycling) • Conditional statements are not permitted • When multiple starts, a common start node can be used to indicate a clear project beginning on the network

6. Developing the Project Plan • AON (Precedence Diagramming) Fundamentals • Activity = node = box • Arrows = dependencies (how activities are related and sequence; length & slope are arbitrary) • Predecessor activities = activities that must be completed before this activity • Successor activities = activities that must follow this activity • Concurrent/parallel activities = activities that can occur while this activity is taking place • Review Table 6.1 (p. 158) and figure 6.4 (p. 159) in text for illustration of basic network

7. Developing the Project Plan • Start & Finish Network Computations • Start/end dates take the network map that shows dependencies and sequences, and adds schedule (time/duration estimates) • Permits estimate of how long the project will take, when activities must start/end, when resources are available, which activities can be delayed • Supports assessment of resource needs, determination of constraints (time or resources) • Links planning, scheduling & controlling of the project

8. Developing the Project Plan • Network Computations • Forward Pass (Earliest times) • Early start – ES: How soon can the activity start • Early finish – EF: How soon can the activity finish • Expected time – TE: How soon can the project be finished • Backward Pass (Latest times) • Late start – LS: How late can the activity start • Late finish – LF: How late can the activity finish • Critical path – CP: Which activities are on the critical path; the longest path in the network, which, if delayed, will delay the project • Slack – SL: How long can the activity be delayed

9. Developing the Project Plan • Forward Pass • Begins with first project activities and traces each path (chain of sequential activities) through the network to the last project activity(ies) • Activity times are added as you trace along the path • Longest path (duration) is critical path • 3 computations: • Add activity times along each path in the network (ES + Dur = EF) • Carry the EF to the next activity where it becomes the ES • If the next succeeding activity is a merge activity (e.g., two or more tasks precede a given activity), select the largest EF number of all immediate predecessor activities

10. Developing the Project Plan • Backward Pass • Starts with the last project activity(ies) and trace backward to find the LS and LF times for each activity • Activity times are subtracted as you trace along the path • Before the backward pass can be computed, the LF for the last project activity must be selected • In the early planning stages, this time is usually set to equal the EF of the last project activity OR, in the case of multiple finish activities, the activity with the largest EF • 3 computations: • Subtract activity times along each path starting with the end activity (LF – Dur = LS) • Carry the LS to the next preceding activity to establish its LF, unless • The next preceding activity is a burst activity; then select the smallest LS of all immediate successor activities to establish the LF

11. Developing the Project Plan

12. Developing the Project Plan • Determining Slack (Float) • Done after forward/backward pass as been determined • Slack helps determine which activities can be delayed • After slack for each activity is computed, critical path(s) is (are) easily identified • Critical path includes those activities that have zero slack (either LF – EF = 0, or LS – ES = 0) . Critical path is the network path(s) that has (have) the least slack in common • Problem arises when the finish activity has an LF that is different from the EF found in the forward pass (e.g., an imposed duration/completion date) > See figure 6.8 (p. 166) in the text • Two formulas: • SL = LS – ES or • SL = LF – EF

13. Developing the Project Plan • Free Slack (Float) • Activity specific slack • Difference between the EF of an activity and the ES of the activity that follows it • Only activities that occur at the end of a chain of activities (usually when you have a merge activity) can have free slack > See Activity “E” in Figure 6.8 (p. 166) of the text • Permits activity to be delayed without delaying the ES of activities following it • Changes in start and finish times for the free slack activity require less coordination with other participants in the project and and give the PM more flexibility than total slack

14. Developing the Project Plan • Using Forward/Backward Pass Info. • Permits flexibility in scheduling project resources (personnel & equipment) that are used on more that one parallel activity or another project • ES and LF identify the time interval in which the activity should be completed • Example (p.166) – Activity “E” has duration of 15 days; can start as early as day 20 and be completed as late as day 200 • Activity “F” must start on day 20 or the project will be delayed • Focusing on critical path activities minimizes risk that delay will occur • If earlier date is required, you can select those activities (or combination) that will cost the least to shorten the project • If critical path is delayed, you can identify the activities on the critical path that will cost the least to shorten

15. Developing the Project Plan • Project Network Activities & Level of Detail • Typically, activities represent one or more tasks from a work package > How many tasks to include in an activity • Too much detail – impossible/costly to manage • Too little detail – precludes effective control & monitoring

16. Developing the Project Plan • Practical Considerations • Logic Errors • Avoid conditional statements (network is not a decision tree) • Conditional statements render forward/backward pass useless • Avoid looping – activity should only occur once (precludes illogical precedence relationships) • If an activity occurs again, it should have a new name, identification number, and be place in the correct sequence on the network • Activity Numbering • May be numeric, alphabetic, or alphanumeric • Generally number in ascending order • Leave gaps between numbers (to add missing/new activities • Recommend numbering after network completion

17. Developing the Project Plan • Practical Considerations • Computerized networks • Gantt charts (bar charts) provide easy-to-understand, clear picture on a timescale horizon • Two-dimensional – Activities down the rows; time across the horizontal axis • Calendar dates • Use calendar and number work days sequentially • Use computerized programs

18. Developing the Project Plan • Extended Network Techniques • Forward/backward pass method assumes that all preceding activities must be 100% complete before connected successor activities can begin > Assumption is too restrictive for some situations • Laddering • Permits succeeding activity to be broken into smaller segments to permit starting of work before preceding activity is entirely completed • Examples: Trenching & pipe laying; road base & paving; auto assembly line

19. Developing the Project Plan • Extended Network Techniques • Lags • Minimum amount of time a dependent activity must to delayed to begin or end • Provide for a more realistic representation of the project • Occur because: • When activities of long duration delay the start of finish of successor activities, the activities are generally broke down into smaller activities to avoid long delays of successor activities • Lags can be used to constrain the start & finish of an activity • Include start-to-start, finish-to-finish, start-to-finish, and finish-to-start

20. Developing the Project Plan • Lags (continued) • Finish-to-start • Involves delaying next activity in a sequence even when the preceding activity is complete • Examples: • Removing concrete forms until concrete has cured for two time units • Ordering and receipt of material – activity takes 1 day with a lag of 29 days > ensures that the activity is tied to placing the order than charging the activity for 30 days or work

21. Developing the Project Plan • Lags (continued) • Start-to-start • Succeeding activity cannot begin until specified lag from preceding activity has occurred • Permits compression (particularly in finish-to-start activities) by permitting sequential activities to be performed in parallel • Example: Certain construction activities may begin after early design activities have been completed > foundation work

22. Developing the Project Plan • Lags (continued) • Finish-to-finish • Finish of one activity depends on finish of another activity • Example: Testing cannot be completed until four days after the prototype is complete (subcomponents may be tested during this time, but prototype “system” test cannot begin)

23. Developing the Project Plan • Lags (continued) • Finish-to-start • Finish of one activity cannot take place until another activity has started • Example: System documentation cannot be completed until three days of testing has begun > relevant documentation has been produced after the first three days of testing