Dynamic Minimum Lag Relationship - Construction Project Scheduling and Control - page 339

percent complete. For example, the production rate for activity A until
the end of day 15 should be:

Performed work ( Quantity )∕ Productive duration ( i . e ., 10 not 15 days )

Another point to be taken into consideration: did the work stop on activity
B during all or part of the stoppage of activity A? If yes, then what is the
true actual duration for activity B? If we assume that activity B stopped when
activity A did, then

AD B = 7 days and RD B is calculated the same as in part 2 earlier,
that is

, 13 days.

This is an important point, in general, for calculating actual duration, AD ,
and at-completion duration, ACD . These two variables are part of the calcula-
tion of production rates and percent complete, two very important parameters
in project management, not only in scheduling but also for estimating and
finance.

Example 12.2

In the previous example, let's take a different and opposite case: the produc-
tion in the predecessor activity (Roof Sheathing) was faster than estimated.

Project Update and Solution

Using traditional CPM relationships:

1. Day 10 (end of day 10): Assume 70% of activity A (Roof Sheathing) is
completed:

Activity A: Started on time: end of day 0, that is, beginning of day 1

Actual duration = 10 days

Remaining duration = 10 days ( no update was done )

At completion duration = 20 days

Activity B (Install Shingles): Started end of day 3, that is, 2 days earlier
than scheduled.