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Critical Project Management
Critical Path Management
Critical Path Method
Crash Project Method
PERT is probabilistic in nature.
CPM is deterministic in nature.
CPM is event-oriented.
CPM and PERT use similar terminology but were developed independently.
A project is a set of activities that can be performed in a certain logical sequence.
A network is a graphic portrayal of independency relationship among the activities of a project.
An arrow representing an activity can have any length and shape.
An activity cannot be represented by more than one arrow but an arrow can represent one or more activities.
All the predecessor(s) of an activity should be focussed on.
Only immediate predecessor(s) should be focussed on.
Redundant predecessors should be dropped.
Care must be taken that there is no logical fault in it as may result in formation of a loop.
The head event of an activity also represents tail event of its predecessor activity.
Nodes should be numbered in such a way that, for every activity, the initial node bears a lower number while final node bears a higher number.
The event marking start of an activity called head event and the event marking the end is termed as tail-event.
In drawing a network, it may happen that A precedes B, B precedes C, and C precedes A.
Each defined activity is represented by one and only one arrow.
A network should have only initial and one terminal node.
Identical initial and final nodes can identify two activities.
Only as few dummy activities should be included as is warranted.
Forward pass calculations yield the earliest and the latest start and finish times of various activities.
The difference between the latest and the earliest finish times of an activity is its total float.
Free float of an activity cannot exceed its total float.
Determination of the earliest and the latest start time of various activities of a project is useful for proper planning of their execution.
Its free float is three days.
Its independent float is 0.
It is a critical activity.
The ES of this activity is 8.
All activities on a critical path are critical activities.
A project network may have none, one, or more critical paths.
A delay in critical activity surely delays the completion of project.
Each critical activity has identical earliest and the latest start times.
Interfering float = Total float – Free float
Total float =Free float + Independent float
Total float ≥ Free float ≥ Independent float
Free float = Total float – Head event slack
Expected time of an activity is a weighted average of three times estimates, a, m, and b with respective weights of 1, 4, and 1.
The completion time of an activity is assumed to follow normal distribution.
The standard deviation of activity completion time is one-sixth of the excess of pessimistic over optimistic time.
The sum total of variances of critical activity times gives the variance of the overall project completion time.
Always focus on critical path and choose between critical activities only.
Crashing cost per day = (Crash cost – Normal cost) / (Normal time – Crash time).
Of all activities of the project, choose the activity with least crashing cost.
If there are multiple critical paths, crash them all.
An event that represents the initiation of more than one activity is called the burst event.
The longest path of a given project gives the maximum duration while its shortest path indicates the shortest duration.
The resource allocation programmes aim to allocate the given resources in a manner that the project completes in minimum time.
A non-critical activity may or may not have any free float.