Critical path method for PE Civil Construction

The governing sequence

The forward pass determines earliest start and earliest finish. At a merge, use the maximum incoming earliest finish. The backward pass determines latest finish and latest start. At a burst, use the minimum outgoing latest start. Total float is LS - ES or LF - EF.

Exam-ready workflow

• Confirm the precedence relationships before calculating dates.
• Complete the full forward pass and identify the project duration.
• Begin the backward pass from the project completion time.
• Calculate total float consistently and identify the controlling path.
• When durations or logic change, recompute the network rather than modifying only one activity.

Common failure modes

A frequent error is using the minimum predecessor finish at a merge or the maximum successor start in the backward pass. Another is calling every zero-float activity critical without checking whether the activities form a continuous controlling path under the stated calendar and constraints.