The Critical Path Method (CPM) - Construction Project Scheduling and Control - page 78

The preceding logic is similar to that of the forward and backward passes: when
you are going forward, pick the largest number; when you are going backward, pick
the smallest number.
Example 4.6
Perform the CPM calculations, including the event times, for the arrow network
shown in Figure 4.14a.
Figure 4.14 (a) Arrow network for example 4.6; (b) event times in arrow network
Solution
Early Times, T E . We start the project at node 10 with an early event time of
T E = 0 (Figure 4.14b). Event (node) 20 is reached when activity A is complete,
which is on day 10. However, event 30 requires both A and B to be completed.
In this case, we take the larger of ( 0 + 10 = 10 ) and ( 0 + 5 = 5 ) ,whichis
10, for the early time. The early time for event 40 is 0 + 7 = 7. Event 50
needs activities D, E, and F to be finished. We take the largest date of 18,
19, and 11 for the early time. The answer is 19. Similarly, early events 60
and 70 have early times of 24 and 27, respectively. Late times, T L , starting