Dynamic Minimum Lag Relationship - Construction Project Scheduling and Control - page 336

Project Update and Solution

1. Using traditional CPM relationships, we calculate the regular early and
late dates for both activities at day 0, that is, before any work occurs.
2. By day 10 (end of day 10), assume only 40% of activity A (Roof Sheath-
ing) 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 ( productivity will pick up in the last

10 days )

At completion duration = 20 days

Activity B : Started end of day 3, that is, 2 days earlier than scheduled

Actual duration = 7days

Remaining duration = 11 days ( assuming the end of activity A + 1day )

Using the DML equation:

AD B ( 1 − PC A )+ L
PC A

RD B ≥

RD B ≥ [ 7 ( 1 − 0 . 40 )+ 1 ]∕ 0 . 40 = 13 days

Finish date for Activity B day 23, not day 21 as calculated by the

≥

FF relationship.

3. Day 15: Assume only 70% of activity A (Roof Sheathing) is completed:

Activity A:

Actual duration = 15 days

Remaining duration = 5days

At completion duration = 20 days

Activity B:

Actual duration = 12 days

Remaining duration = 6days ( Assuming the end of activity A + 1day )