Precedence Networks - Construction Project Scheduling and Control - page 103

b. Activity B is connected to A by a combination relationship:
i. The SS relationship (with no lag) means B can start just after A has
started. This means activity B's ES = 0.
EF = ES + Dur = 0 + 7 = 7 so the early dates are (0, 7)
ii. The FF relationship (with no lag) means B can finish just after A is
complete:
EF (B)= EF (A)+ Lag (if any)=5 + 0 = 5
ES = EF - Dur = 5-7=−2sotheearlydatesare(−2, 5)
The second answer violates the SS relationship so the first answer
prevails.
c. The same method applies to activity C:
i. The SS relationship (with no lag) means C can start just after B has
started. This means activity C's ES = 0.
EF = ES + Dur = 0 + 3 = 3 so the early dates are (0, 3)
ii. The FF relationship (with no lag) means C can finish just after B is
complete:
EF (C)= EF (B)+ Lag (if any)=7 + 0 = 7
ES = EF - Dur = 7-3= 4 so the early dates are (4, 7)
The first answer violates the SS relationship so the second answer
prevails.
d. In the backward pass, we start at the end of activity C with its finish no
earlier than day 7: LF = 7; LS = LF − Dur = 7 − 3 = 4, so the late dates are
(4, 7)
e. For activity B:
i. The FF relationship (with no lag) means B can finish just before C is com-
plete, LF (B) = LF (C) − Lag = 7 − 0 = 7. LS = LF − Dur = 7 − 7 = 0,
so the late dates are (0, 7)
ii. The SS relationship (with no lag) means B can start just before C starts,
LS (B) = LS (C) − Lag = 4 − 0 = 4. LF = LS + Dur = 4 + 7 = 11, so the
late dates are (4, 11)
The second answer delays the completion of the project, so it is
rejected. The first answer prevails.
f. Activity A:
i. The FF relationship (with no lag) means A can finish just before B is com-
plete, LF (A) = LF (B) − Lag = 7 − 0 = 7. LS = LF − Dur = 7 − 5 = 2,
so the late dates are (2, 7)