Page 160 - DCAP601_SIMULATION_AND_MODELING

Simulation and Modelling

Notes 4. PERT activity: The actual presentation of a task which consumes time and requires resources
(such as labor, materials, space, machinery). It can be understood as representing the time,
effort, and resources required to move from one event to another. A PERT activity cannot
be performed until the predecessor event has occurred.
5. Optimistic time (O): The minimum possible time required to achieve a task, assuming
everything proceeds better than is normally expected
6. Pessimistic time (P): The maximum probable time required to accomplish a task, assuming
everything goes wrong (but excluding major catastrophes).

7. Most likely time (M): The best estimate of the time necessary to accomplish a task, assuming
everything proceeds as normal.
8. Expected time (T ): The best estimate of the time required to accomplish a task, accounting
E
for the fact that things don’t always continue as normal (the implication being that the
expected time is the average time the task would require if the task were repeated on a
number of occasions over an extended period of time).
T = (O + 4M + P) ÷ 6
E
9. Float or Slack is the quantity of time that a task in a project network can be delayed
without causing a delay - Subsequent tasks – (free float) or Project Completion – (total
float)

10. Critical Path: The longest likely continuous pathway taken from the initial event to the
terminal event. It determines the total calendar time required for the project; and, therefore,
any time delays along the critical path will delay the reaching of the terminal event by at
least the same amount.

11. Critical Activity: An activity that has total float equal to zero. Activity with zero float
does not mean it is on the critical path.
12. Lead time: The time by which a predecessor event must be completed in order to allow
sufficient time for the activities that must elapse before a specific PERT event reaches
completion.
13. Lag time: The earliest time by which a successor event can follow a specific PERT event.

14. Slack: The slack of an event is a measure of the excess time and resources available in
achieving this event. Positive slack would indicate ahead of schedule; negative slack would
indicate behind schedule; and zero slack would indicate on schedule.
15. Fast tracking: Performing more critical activities in parallel

Did u know? What is Crashing Critical Path?
Shortening duration of critical activities

9.3.2 Achievement

The first step to scheduling the project is to conclude the tasks that the project requires and the
order in which they must be completed. The order may be easy to record for some tasks even as
difficult for others (There are two areas that need to be graded, but there are only sufficient
bulldozers to do one). Additionally, the time estimates usually reflect the normal, non-rushed
time. Many times, the time required to perform the task can be reduced for an additional cost or
a reduction in the quality.

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