EDP Notes

Path: It refers to unbroken or continuous chain of activities from the start event to end
event in the network diagram.
Critical Path: It is the path which takes longest duration. It is represented by double or
thick arrow line to distinguish it from the other non critical paths.
Critical Activities: These are activities lying in the critical path and its delay in start will
cause a further delay in the completion of the entire project. Activities with zero floats are
called critical activities. Such activities require special attention.
Preceding Activities: Activities that must be completed immediately prior to the start of
another activity are called predecessor activities.
Succeeding Activities: Activities that cannot be started until one or more of other activities
are completed but immediately succeed are called successor activities

Earliest Start Time (EST): it is the earliest time an activity can start on the assumption
that all its preceding activities started at the earliest possible times. It is calculated by
moving from first to last event in a network diagram.
Latest Start Time (LST): It is the latest possible time an activity can finish without
delaying the project on the assumption that all subsequent activities are finished as planned.
It is the difference between the latest finish time and the estimated time for the activity to
be completed.
Earliest Finish Time (EFT): It is the sum of the earliest start time and the estimated time
to perform the activity. (i.e., EST+ activity duration)
Latest Finish Time (LFT): It is calculated by moving backward ie, from last event to first
event of the network diagram.
Forward Pass: The objective is to determine the earliest expected start and finish of the
constituent activities of a project.
Backward Pass: It is the process of determining the latest allowable starting and finishing
time of an activity. The computation starts at the end event of a project and moves
backwards.
Float (Total Float): It means the amount of excess or spare time up to which an activity
can be delayed without affecting the overall completion time of the project. It is the
difference between the latest finish time and earliest start time.
Total Float= LFT – EFT or LST – EST
Free Float: It is the excess of the available time over the required time when the activity, as
well as its successor activity start as early as possible.
Free Float = EST of the successor – EFT of the present Activity
Independent Float: It is the amount of time an activity could be delayed if preceding
activities finish at their latest and subsequent activities start at their earliest.
Independent Float = EST of successor – LFT of predecessor – Duration.
If a negative value of independent float is obtained, then independent float is taken as zero.