Pauses or delays between activities are indicated in the network diagram.

2.5 Schedule Development

To establish the project schedule, compute two schedules:

l The early schedule is calculated using the forward pass.

The early schedule consists of the earliest times at which an activity can start and finish

l The late schedule is calculated using backward pass.

The late schedule consists of the latest times at which an activity can start and finish without delaying the completion date of the project

2.5 Schedule Development

The combination of both schedules gives two additional information about the project schedule:

l The window of time within which each activity must be started and finished

l The sequence of activities that determine the project completion date

The Critical path, can be defined:

Is the sequence of activities whose early schedule and late schedule are the same,

This is the sequence of activities with zero slack

2.5 Schedule Development

The Earliest Start (ES)

l TheES time for an activity is the earliest time at which all of its predecessor activities have been completed and the activity can begin.

l The ES time for an activity with no predecessor activities is set to 1, the first day of the project

l The ES time of activities with one predecessor activity is determined from the EF time of the predecessor activity

l The ES time of activities having two or more predecessor activities is determined from the latest of the EF times of the predecessors

2.5 Schedule Development

The Earliest Finish (EF)

EF = ES + E – 1 time unit; E is duration

2.5 Schedule Development

Latest Start (LS) and Latest Finish (LF)

The LS and LF times of an activity are the latest times at which the activity can start or finish without causing a delay in the completion of the project

To calculate LS and LF times:

Work backward in the network diagram

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