Table of Contents
Critical Path Method:
Project management technique that is used when activity times are deterministic. The critical path method (CPM), or critical path analysis (CPA), is an algorithm for scheduling a set of project activities. It is commonly used in conjunction with the program evaluation and review technique (PERT). A critical path is determined by identifying the longest stretch of dependent activities and measuring the time required to complete them from start to finish.
There are following components of CPM (Critical Path Method):
- Activity : Distinct part of a project, involving some work, whose completion requires some amount of time. e.g. drilling a hole, starting a bus, issuing the work order, floating a tender, etc.
- Activity duration : It is the physical time required to complete an activity. In CPM, it is the best estimate of the time to complete an activity. In PERT, it is the expected time or average time to complete an activity.
- Critical activity : This activity has no room for schedule deviation. In case of deviation or slips, the entire project completion will slip. An activity with zero slack is also same.
- Critical path : The sequence or chain of critical activities for the project constitutes critical path. It is the longest duration path through the network.
- Crashing : The process of reducing an activity time by adding fresh resources and hence usually increasing cost. Crashing is needed for finishing the task before estimated time.
- Crash cost : Cost associated with an activity when it is completed in the possible time (crash time), which is lesser than the expected or normal time.
- Dummy activity : An activity that consumes no time but and zero resource only function of these activity is to designate a precedence relationship shows precedence among activities. It is useful for proper representation in the network.
- Earliest Finish (EF) time : The earliest time that an activity can finish, from the beginning of the project.
- Earliest Start (ES) time : The earliest time that an activity can start, from the beginning of the project.
- Event : It is the beginning, completion point,or milestone accomplishment within the project. An activity begins and ends with events. An event triggers an activity of the project.
- Expected activity time : The average activity time that is used in the project scheduling.
- Free slack (float) : The length of time up to which an activity can be delayed for channeling resources or readjustments, without affecting the starts of the succeeding activities.
- Immediate predecessor : An activity, which should immediately precede the activity under consideration.
- Latest Finish (LF) time : It is the latest time that an activity can finish, from the beginning of the project, without causing a delay in the completion of the project.
- Latest Start (LS) time : It is the latest time that an activity can start, from the beginning of the project, without causing a delay in the completion of the project.
- Most Likely time ( tm ) : It is the time for completing an activity that is the best estimate; under the given conditions (used in PERT).
- Normal cost : Cost associated with an activity when it is completed in normal time.
- Optimistic time ( to ) : It is the time for completing an activity if everything in the project goes well (used in PERT).
- Pessimistic time ( tp ) : It is the time for completing an activity if everything in the project goes wrong (used in PERT).
- Predecessor activity : An activity that must occur before another activity in the project which is decided on precedence relationship.
- Project : Set of activities which are interrelated with each other and are to be organized for a common goal o objective during a specified time-frame.
- Project network : A visual representation of the interdependence between different activities of a project which are normally associated with a time-wise sequencing.
- Resource allocation methods : Allocation of resources to the activities so that project completion time is as small as possible and resources are well utilized.
- Slack : It is the amount of time that an activity or a group of activities can delay in getting completed without causing a delay in the completion of the project. An activity having slack cannot be critical activity.
- Successor activity : It is the activity that must occur after another activity (which is predecessor).
- Total slack (Float) : The time up to which an activity can be delayed without affecting start of the succeeding activities.
- Updating : It involves some revision of the project schedule after partial completion with revised information.
- Variance : It is the measure of deviation of the time distribution for an activity.