Project Management in the Oil and Gas Industry

3.5 Time Schedule Preparation
Now you have a plan for the work and the time period for each activity. 
The most important thing in preparing the time schedule is to identify 
the activity and determine the time required for its implementation with 
the identification of relations between the activities. How to determine the 
activities and knowledge of time of each activity has been presented, so we 
must now know how to arrange the activities.
The different common relation between activities is as shown in 
Figure 3.3.
1. Activity (B) cannot start until the finish of activity (A).
2. Activity (A) and (B) start at the same time.
3. Activity (A) and (B) finish at the same time.
Finish to start
A
B
Start to start
A
B
Finish to finish
A
B
Figure 3.3 Activities order.

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Pitfalls in Time Schedule Planning 95
In some cases, activity A may begin and, after a certain time period, 
activity B begins. This period is called the “lag time.”
A computer can perform this task easily, but, in general, there are two 
main methods: the arrow diagram and the precedence diagram, as shown 
in Figure 3.4.
3.5.1 Gantt 
Chart 
In general, the relations between activities are usually in series or parallel. 
The relation depends on the nature of the activities and this should be con-
sidered in preparing the time schedule.
The Gantt chart is the oldest and most traditional method used to present 
project schedules to this day. But, the relations between all the activities are 
not presented well by this method and you cannot go through the detailed 
activity as accurately. Therefore, it would only be useful in presentations 
for high-level management, as it presents enough information for level one 
of the schedule, but for more detail another method is needed.