1. Network diagram

*Notes:

EST: Earliest start time

EFT: Earliest finish time

LST: Latest start time

LFT: Latest finish time Non-critical path Critical path

2. Timing of activities and total float

Base on the methodology in the text: Project Management, Field and Keller (2007.p.197, p.198 & p.391), we can using forward pass and backward pass to calculate EST, EFT, LST and LFT

a. Forward pass

The formula to calculate the forward pass is:

EST = EFT of preceding activity

EFT = EST + activity duration

To calculate the EST of activities, we start from the start node. We assume that the starting time is 0. Base on the formula above, EFT of activity A = 0 + 4 = 4 days. According to the formula EST = EFT of preceding activity, we can also calculate the next activity. Thus, EST of activity B is 4 days. However, when there is one activity depend on more than one activity before, the following activity’s EST have to get the highest of preceding EFT to ensure all of preceding activities are complete. As we can see in the diagram, the activity K has three preceding activities (H, I, J) and the activity I has the highest value of EFT, which is 28. Thus, the EST of activities K is 28.

b. Backward pass

The calculations start from the last activity in the network diagram and working backward.

LST = LFT – activity duration

LFT= LST of next activity

In order to correct the time for each activity, one activity has more than one activity stand before, the LFT of this activity will get the lowest value of LST of immediately activity after. For example, the LST of activity the E is lower than F (13