Critical Path Method By Matthew Gordon IST 402

Critical Path Method By Matthew Gordon IST 402 – Professor Kochanov

History/ Background • Critical Path Method (CPM) – Du-Pont wanted a better method to build and maintain its chemical plants. – The availability of computers such as UNIVAC 1 assisted in development. – CPM can be used for varying types of projects ranging from simple to extremely complex.

What is the Critical Path Method • Provides a way to identify how quickly a project can be completed. • Shows which activities could be time bottlenecks. • Tends to use Network Diagrams for visual representation of durations. • Inputs for each Activity: – Expected duration. – Immediately proceeding activity.

How CPM Can Be Used • The most simple form would be a table listing the inputs for the activities: Task ID Task Description Duration (Seconds) Prerequisites 0 Turn on water 3 None 1 Apply Soap 5 0 2 Wash Hands 60 1 3 Dry Hands 12 2 • But you could also make it into a simple Network Diagram:

More Ways to Use CPM • GANTT Chart:

Additional Schedules • Early Start: – Earliest a task can start assuming its predecessors are complete. – For every activity that has scheduled predecessors, schedule it to start ASAP. • Late Start: – The latest a task can start and allow the project to stay on track. • Slack: – Difference between Late and Early Start Schedules. – Tasks with zero slack, must be completed on time or they will delay the project.

Critical Paths • A project can have more than one critical path. • Shortest amount of time a project can be completed in. • Can be depicted via: – GANTT charts – Network Diagrams – Arrow on Node diagram (AON) – Arrow on Arrow diagram (AOA)

Buffers • Project Buffers – Used to pad a project to ensure it finishes on time. • Feeding Buffers – Used where a non-critical activity affects one on the critical path. – Also allows for early start of critical path item.

Buffers • Resource Buffers – Ensures the availability of resources including people; i. e. if a employee is able to work on a project earlier than expected. • Strategic Resource Buffers – Designed to ensure that key resources are available for critical activates.

Resource Leveling • Designed to allow for the most efficient use or a resource without over scheduling the resource at the same time. • Methods: – Schedule tasks that require a certain individual or equipment close together if at all possible. – Don’t bring equipment or staff on site until needed.

Criticisms • It’s a mathematical model that assumes everything will go as planned. • Assumes unlimitedresources and their constant availability. • Assumes that tasks have a clear beginning and end, and does not address the possibility of variations in task duration. • Assumes project requirements will not change during project.

Questions • ?

Works Cited • HPC. “History of Critical Path Method. ” <http: //www. hpcconsult. co. uk/educational_ser vices/planning_academy/04 -cpm-history. asp> 3/13/2005. • Olson, David. “Managerial Issues of Enterprise Resource Planning Systems. ” Mc. Graw-Hill/Irwin. New York, New York. 2004. pp 83 -98. • Witcombe, Mike. “Critical Analysis. ” <http: //www. waainc. com/projex/PERT/aon. htm> 3/13/2005.