1. 1 Selected Topics on Project Management The Critical Path Dr Marc Conrad http://perisic.com/stpm 1Marc Conrad

2. 2 Dependency Diagrams Project Schedule Network Diagrams Provide a quick and easy way to see snapshot of tasks and their dependencies. Either Activity on Node (AON) or Activity on Arrow (AOA). Let’s focus on AOA diagrams here. Project Management software often allows to produce network diagrams from Gantt charts. 2Marc Conrad

3. 3 Example Network Diagram A,B,C,… are activities. Activity A needs 1 day, activity B needs 2 days, etc. D = 4 A = 1 B = 2 C = 3 G = 6 E = 5 F = 4 I = 2 J = 3 H = 6 3Marc Conrad

4. 4 Critical Path – What is it A critical path for a project is the series of activities that determine the earliest time by which the project can be completed. It is the longest path through a network diagram and has the least amount of slack or float. Slack (or float) – amount of time an activity may be delayed without delaying a succeeding activity or project finish date. 4Marc Conrad

5. 5 Critical Path Analysis Critical Path analysis is the process of identifying the critical path for a project. Use the critical path to keep an eye on how things are progressing, and can use this as a benchmark. Without knowing what the critical path is we cannot (necessarily) know how we are doing, or what the earliest finish date is. Allows to make so-called schedule trade-offs (more later) Calculating the critical path involves adding the durations of all activities on each path through the network. The longest path is the critical path 5Marc Conrad

6. 6 Example Path 1: A-D-H-J: 1 + 4 + 6 + 3 = 14 days D = 4 A = 1 B = 2 C = 3 G = 6 E = 5 F = 4 I = 2 J = 3 H = 6 6Marc Conrad

7. 7 Example Path 2: B-E-H-J: 2 + 5 + 6 + 3 = 16 days D = 4 A = 1 B = 2 C = 3 G = 6 E = 5 F = 4 I = 2 J = 3 H = 6 7Marc Conrad

8. 8 Example Path 3: B-F-I-J: 2 + 4 + 2 + 3 = 11 days D = 4 A = 1 B = 2 C = 3 G = 6 E = 5 F = 4 I = 2 J = 3 H = 6 8Marc Conrad

9. 9 Example Path 4: C-G-I-J: 3 + 6 + 2 + 3 = 14 days D = 4 A = 1 B = 2 C = 3 G = 6 E = 5 F = 4 I = 2 J = 3 H = 6 9Marc Conrad

10. 10 Example Summary There are four paths: A - D – H - J = 1 + 4 + 6 + 3 = 14 days B – E – H – J = 2 + 5 + 6 + 3 = 16 days B – F – I – J = 2 + 4 + 2 + 3 = 11 days C – G – I – J = 3 + 6 + 2 + 3 = 14 days The path B-E-H-J is the longest, and is therefore the critical path ! 10Marc Conrad

11. 11 Properties of the Critical Path Summary The critical path shows the shortest time in which a project can be completed. If one or more activities on the critical path takes longer than predicted, the whole project schedule will slip. We can only reduce the time a project will take if we reduce the duration of tasks on the critical path. There can be more than one critical path. 11Marc Conrad