1. Project Management (2) Chapter 16, Part 2

2. EJR 2006 Review of Project Management, Part 1 What is a project? Examples of projects Project performance expectations Project life cycle phases Ways to set up a project team Determining a project schedule (part 1): determine project duration

3. EJR 2006 Determine Project Duration 1. Set up a network diagram 2. Identify the paths 3. Compute the length of each path 4. The longest path is the critical path. 5. Project duration = length of critical path

4. EJR 2006 Project Management Outline of Part 2 Critical and non-critical activities Scheduling definitions Scheduling computations Objectives Formulas Steps in scheduling computations Early start and late start schedules

5. EJR 2006 Critical Activities Critical activities are those on the critical path. Critical activities should be completed on time to avoid delaying project completion. If a critical activity is not completed on time, the schedule must be adjusted so that the project can still be finished on time. This requires spending more money for additional equipment, extra workers, or overtime labor For a critical activity, there is only one start date and one end date that will allow the project to be completed on time without spending extra money.

6. EJR 2006 Non-critical Activities Non-critical activities are not on the critical path. For a non-critical activity, there is a range of start dates and a range of end dates that will allow the project to be completed on time without spending extra money. In scheduling non-critical activities, we can consider factors such as cash flow and resource availability.

7. EJR 2006 Spaghetti Example We want to eat in 34 minutes, which is the duration of cooking time. Find the earliest and latest start times for activity F. Find the earliest and latest finish times for activity F. Find the earliest and latest finish times for activity G. Find the earliest and latest start times for activity G.

8. EJR 2006 Scheduling Terms For each activity in a project: The early start (ES) is the earliest time that an activity can be started. The early finish (EF) is the earliest time that an activity can be finished. The late finish (LF) is the latest time that an activity can be finished. The late start is the latest time that an activity can be started.

9. EJR 2006 Objectives of Scheduling Computations To determine the acceptable start and end dates for each activity. These computations can also be used to determine project duration and the critical path. To provide a basis for developing a project schedule

10. EJR 2006 Steps in Scheduling Computations 1. Set up a network diagram 2. Working from left to right (L  R), compute ES and EF for each activity. 3. Project duration = EF for last activity. 4. Working from right to left (R  L), compute LF and LS in that order for each activity. 5. For each activity, compute slack = LF – EF = LS – ES 6. The critical path is the set of activities with zero slack.

11. EJR 2006 Computing ES and EF Work from left to right (L  R) For first activity, ES = 0 For all other activities, ES = Largest {EF for immediately preceding activities} For all activities, EF = ES + activity time (inside the circle or box)

12. EJR 2006 Computing LF and LS Work from right to left (R  L) For last activity, LF = EF For all other activities, LF = smallest {LS for immediately following activities} For all activities, LS = LF – activity time

13. EJR 2006 Slack and the Critical Path Slack tells us how much flexibility we have in scheduling each activity slack = LF – EF = LS – ES The critical path is the set of activities with zero slack.

14. EJR 2006 ES and LS Schedules In an early start (ES) schedule, each activity begins at time ES and ends at time EF In a late start (LS) schedule, each activity begins at time LS and ends at time LF Other schedules may be possible. For all activities, we must have ES < start time < LS The activity must start between ES and LS (inclusive)