PERT/CPMPERT/CPM

ByBy

Bhupendra Ratha, LecturerBhupendra Ratha, LecturerS. L. I. Sc., S. L. I. Sc.,

D.A.V.V., IndoreD.A.V.V., IndoreEmail Id: Email Id: bhu261@gmail.combhu261@gmail.com

PERTPERT

Project Evaluation and Review Technique Project Evaluation and Review Technique (PERT)(PERT)– U S Navy (1958) for the POLARIS missile U S Navy (1958) for the POLARIS missile

programprogram– Multiple task time estimates (probabilistic nature)Multiple task time estimates (probabilistic nature)– Activity-on-arrow network constructionActivity-on-arrow network construction– Non-repetitive jobs (R & D work)Non-repetitive jobs (R & D work)

Need of PERT/CPMNeed of PERT/CPM

Prediction of deliverablesPrediction of deliverables Planning resource requirementsPlanning resource requirements Controlling resource allocationControlling resource allocation Internal program reviewInternal program review External program reviewExternal program review Performance evaluationPerformance evaluation Uniform wide acceptanceUniform wide acceptance

Use of PERTUse of PERT

In construction activities In construction activities Transportation activitiesTransportation activities In oil refineriesIn oil refineries Computer system-Computer system- For manufacturing electric generator machinesFor manufacturing electric generator machines Medical and surgical sectorMedical and surgical sector Library activitiesLibrary activities

Importance of PERT systemImportance of PERT system

Reduction in costReduction in cost Saving of timeSaving of time Determination of activitiesDetermination of activities Elimination of risk in complex activities –Elimination of risk in complex activities – FlexibilityFlexibility Evaluation of alternatives-Evaluation of alternatives- Useful in effective control-Useful in effective control- Useful in decision makingUseful in decision making Useful is research workUseful is research work

History of CPMHistory of CPM

Critical Path Method (CPM)Critical Path Method (CPM)– E I Du Pont de Nemours & Co. (1957) for E I Du Pont de Nemours & Co. (1957) for

construction of new chemical plant and maintenance construction of new chemical plant and maintenance shut-downshut-down

– Deterministic task timesDeterministic task times– Activity-on-node network constructionActivity-on-node network construction– Repetitive nature of jobsRepetitive nature of jobs

CPM calculationCPM calculation

PathPath– A connected sequence of activities leading from A connected sequence of activities leading from

the starting event to the ending eventthe starting event to the ending event

Critical PathCritical Path– The longest path (time); determines the project The longest path (time); determines the project

durationduration

Critical ActivitiesCritical Activities– All of the activities that make up the critical pathAll of the activities that make up the critical path

Procedure of PERT/CPMProcedure of PERT/CPM Develop a list of activities that make up Develop a list of activities that make up

project.project. Estimate the completion time for each activity.Estimate the completion time for each activity. Draw a project network and tDraw a project network and t

Benefits of CPM/PERTBenefits of CPM/PERT

Useful at many stages of project managementUseful at many stages of project management Mathematically simpleMathematically simple Give critical path and slack timeGive critical path and slack time Provide project documentationProvide project documentation Useful in monitoring costsUseful in monitoring costs

Limitations to CPM/PERTLimitations to CPM/PERT Clearly defined, independent and stable activitiesClearly defined, independent and stable activities Specified precedence relationshipsSpecified precedence relationships Over emphasis on critical pathsOver emphasis on critical paths Deterministic CPM modelDeterministic CPM model Activity time estimates are subjective and depend on judgmentActivity time estimates are subjective and depend on judgment PERT assumes a beta distribution for these time estimates, but PERT assumes a beta distribution for these time estimates, but

the actual distribution may be differentthe actual distribution may be different PERT consistently underestimates the expected project PERT consistently underestimates the expected project

completion time due to alternate paths becoming criticalcompletion time due to alternate paths becoming critical