Critical Path Method (Cpm):

• CPM technique is used in construction projects based on the knowledge and experience of the past projects for predicting accurately the time required for various activities during the execution of the project.
• Time required for each activity is known and defined for the project.
• Hierarchy of the construction project events are well defined and time of completion of the same is also defined.
• The total time required for the given project can be estimated based on this technique.
• CPM is an activity oriented system as the times required for construction activities are estimated more accurately.
• CPM is used where activities are definable and measurable and minimum overall cost is of the utmost importance.

Program Evaluation And Review Technique (Pert):

• PERT is mainly used where time required for completion of each of the activities involved cannot be accurately defined nor are the resources to be used for the activity readily available.
• The events could however be readily definable. For example, for a construction project type, which have not been completed anywhere in the past, when it is possible to say that an activity A has to be completed before activity b but the time required to complete the activity A is not known or the completion time of activity B is uncertain, in that case PERT technique is used.
• This technique is based on the probabilities of completing each activity in time.
• This technique is therefore most suited to projects like research and development, investigation, design etc.