Other Scheduling Methods - Construction Project Scheduling and Control - page 315

Figure 11.19 Time buffer calculation in the LSM

or

Time buffer = DuartionA − DurationB (11.10)

With multiple activities, you must consider two activities at a time. Starting from
the beginning, do the following:

1. Compare the durations of activities 1 and 2. If activity 2 has a shorter dura-
tion, determine the time buffer from equation 11.10. If activity 2 has a longer
duration, there is no need for a time buffer (practically speaking, we need a
minimum buffer because a predecessor and a successor cannot start at exactly
the same time).
2. Repeat step 1 for activities 2 and 3, and so on.

Example 11.4

A project consists of five activities:

A. Excavating a trench
B. Laying a subbase of gravel
C. Laying a concrete pipe
D. Backfilling
E. Compacting

Assume that the length of the pipe is 1,000 LF and that the productiv-
ity rates for the five activities are 100, 125, 75, 200, and 150 LF per day,