Critical Path Method in project scheduling.

Critical path is an important element in project scheduling. Every scheduler or planner officer need to identify which is the task(s) that will form the critical path of the project. Critical path always consist of series of task or work that must not be delayed, start or commencement date and must finish on a fixed date. If there is any delay occurred in commencement of any task or work that form a critical path, then there is very high possibilities that the project going to be delay in completion. When this situation happened, contractor will have to plan for a catch-up program to make sure that the project can be completed with-in the approved construction period. However in this section we will not discussing on the catch-up program or plan.

How to determine the critical path of a project? In actual fact, regardless of what scheduling software that planner(s) officer or Scheduler(s) officer used to produce a work program or work plan for a project, the basic theory of the Critical path calculation is always the same for any brand of project scheduling software.

There are two types of critical path calculation that can be used to identify a critical path. The two types of calculation are Forward pass calculation and Backward Pass calculation.

Forward pass calculation can be used to determine when or on what date a project can be completed. The calculation will start from the beginning of the project and at the end we will be able to know when a project can be completed with estimated numbers of resources that available.

Backward pass calculation can be used when we are given a fixed date on when to complete a project. This method always required us to analyze the availability of our resources and their output in order to complete the project as required. By knowing our capacity of resources we will be able to estimate the duration required to complete each and single task of a project. With this information than we start the calculation from the given finished date and we will know the latest date we must start our work which normally known as late start.

Theoretically, Critical path will always having the same figure for the early start and the late start. Thus there is no number of floating days allow. Mathematically the float day is equal to “0”. All series of task or works that have no float days or “0” floating days will fall in a critical path of a project.

Critical path in Microsoft project, by default is always colored with red in Gantt Chart.