The Network Diagram

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1.2.ACTIVITIES TIMING AND TOTAL FLOAT

To determine timing of activities in the network diagram the following calculations were done for each node: Earliest Start-(ES), Earliest Finish-(EF), Latest Start-(LS) and Latest Finish-(LF).

Field and Keller (1998, p. 191) ES and EF are found by using the forward pass through the network … from the unique project start node and ends at the unique project completion node.

ES is the ending day for the previous node/activity, where more than one activity preceded an activity, the ES time was taken from the activity whose ending day has the largest number.

EF is the ES added to the duration of the activity (given), e.g. Activity-A, (start node: zero) plus its duration 4 days: EF is 4 days. Activity-A figure becomes the ES for the next successive Activity-B; this sequential calculation is done for all nodes straight to the last project node.

Project duration was calculated using formula-1:

(Field and Keller 1998, p. 190) defined LF as the latest time by which the node must be reached in order for the project to finish by its required completion date. The latest event time is the latest time the node must be reached in order for the project to finish by its required completion date as defined by Field and Keller (1998, p. 190). LS and LF of each activity is calculated using a backward pass.

LF of a node is the LS of the succeeding node and latest day that the project can finish to meet the project duration; where an activity preceded two activities, the LF was taken from the succeeding activity with the smallest LS time.

LS time is the latest day an activity can start for the project to be completed on-time, it is found by subtracting the duration from the LF time. Example: LS of Activity-H(29) becomes LF-(29) of its preceding Activity-G.

Schwalbe (2009, p. 139) Float is the amount of time an activity may be delayed without delaying a succeeding activity or project finish date....
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