CPM - Critical Path Method
- 1. CPM Network Analysis Prepared By : Parth Desani Civil Engineer
- 2. Critical Path Method (CPM) Critical Path Analysis Project Network Concurrent Activities Situations in network diagram AOA & AON Project Networks for House Network example
- 3. Critical Path Method (CPM) • E I Du Pont de Nemours & Co. (1957) for construction of new chemical plant and maintenance shut-down • Deterministic task times • Activity-on-node network construction • Repetitive nature of jobs Identify and prioritise the activities Identify which activities MUST be done before others EST – identify earliest start time LFT – identify latest finish time Identify the FLOAT – tasks which can be completed outside the critical path Identify the critical path – points connecting ESTs and LFTs (where these are the same)
- 4. Nodes: Show the start and finish of a task 1 2 Node numbers showing order of activities in the left hand semi-circle of each node. 3 Earliest Start Time (EST) 5 Latest Finish Time (LFT) A 3 B 5 Arrows indicate the order of the tasks, the letter above shows the order, the time period below the arrow The Critical Path
- 5. Use of nodes and arrows Arrows An arrow leads from tail to head directionally • Indicate ACTIVITY, a time consuming effort that is required to perform a part of the work. Nodes A node is represented by a circle - Indicate EVENT, a point in time where one or more activities start and/or finish. Network analysis is the general name given to certain specific techniques which can be used for the planning, management and control of projects • Activity – A task or a certain amount of work required in the project – Requires time to complete – Represented by an arrow • Dummy Activity – Indicates only precedence relationships – Does not require any time of effort
- 6. Event • Signals the beginning or ending of an activity • Designates a point in time • Represented by a circle (node) Network • Shows the sequential relationships among activities using nodes and arrows Activity-on-node (AON) nodes represent activities, and arrows show precedence relationships Activity-on-arrow (AOA) arrows represent activities and nodes are events for points in time Project Network
- 7. 2 3 Lay foundation Order material (a) Incorrect precedence relationship (b) Correct precedence relationship 3 42 Dummy Lay foundation Order material 1 2 0
- 8. A B C A must finish before either B or C can start A B C both A and B must finish before C can start D C B A both A and C must finish before either of B or D can start A C B D Dummy A must finish before B can start both A and C must finish before D can start
- 9. darla/smbs/vit 9 3 2 0 1 3 1 1 1 1 2 4 6 7 3 5 Lay foundation Design house and obtain financing Order and receive materials Dummy Finish work Select carpet Select paint Build house AON Project Network for House 1 3 2 2 4 3 3 1 5 1 6 1 7 1Start Design house and obtain financing Order and receive materials Select paint Select carpet Lay foundations Build house Finish work
- 10. For clarity, this list is kept to a minimum by specifying only immediate relationships, that is relationships involving activities that "occur near to each other in time". The key question is: How long will it take to complete this project ?
- 11. Is this a Start Activity? Is this a Finish Activity? What Activity Precedes this? What Activity Follows this? What Activity is Concurrent with this? darla/smbs/vit 11
- 12. Path • A connected sequence of activities leading from the starting event to the ending event Critical Path • The longest path (time); determines the project duration Critical Activities • All of the activities that make up the critical path
- 13. CPM Network a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12
- 14. ES and EF Times a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5
- 15. ES and EF Times a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5 5 14 8 21 6 23 6 21
- 16. ES and EF Times a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5 5 14 8 21 21 33 6 23 21 30 23 29 6 21 Project’s EF = 33
- 17. LS and LF Times a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5 5 14 8 21 21 33 6 23 21 30 23 29 6 21 21 33 27 33 24 33
- 18. LS and LF Times a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5 5 14 8 21 21 33 6 23 21 30 23 29 6 21 4 10 0 8 7 12 12 21 21 33 27 33 8 21 10 27 24 33 18 24
- 19. Float a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12 0 6 0 8 0 5 5 14 8 21 21 33 6 23 21 30 23 29 6 21 3 9 0 8 7 12 12 21 21 33 27 33 8 21 10 27 24 33 9 24 3 4 3 3 4 0 0 7 7 0
- 20. Critical Path darla/smbs/vit 20 a, 6 f, 15 b, 8 c, 5 e, 9 d, 13 g, 17 h, 9 i, 6 j, 12