Impact of Changes in CPM Schedule

Time is the most valuable commodity for us today. Everything, including our life, is time-bound. It is the only thing in our life that we can’t spend leisurely. Nor can we wait for the things to happen. We have to force the pace and get things done. It’s true even in case of professional projects where we toil from early morning to late night to complete the work on time.

impact-of-change-in-cpm-scheduleIt is certain that without proper time management, a project can head nowhere. That’s why we pre-plan and schedule everything systematically. Even then there is a possibility of delays and changes to the established schedule which disrupts the pace of the work and make us worried. It’s a frequent occurrence in corporate sector, and more prominent and cost punitive in the construction, software and marketing projects. For example, in the construction industry even brick laying task is time bound. Delays for whatever reason in such a case have a negative impact on the construction schedule of the entire project resulting in huge losses.

Critical path method or the CPM schedule has been designed specifically to overcome this issue. The CPM is used in multitasked projects involving interdependent activities. It is a project planning and management tool and network-based scheduling technique based on mathematical calculations. Tasks that are vital and time bound are usually scheduled in the critical path of the project.

All the project activities nowadays is scheduled and monitored using the CPM. Sequential activities from start to the end of a project, is coordinated through this schedule as a critical path objects. Any change in this schedule, done intentionally or unintentionally, has a strong impact on the overall duration of the project. If there is a delay in any of the activities under the critical path, there invariably will be a delay in the entire project. Most of the times, project acceleration or re-sequencing or rescheduling of the tasks is done to avoid such a delay and accelerate the pace of the project.

It is expected that the project should run smoothly and finish on time. Contrary to this expectation, in most cases, some activities perform poorly. Sometimes, holding a task or changing its schedule becomes mandatory. Other times, natural disasters force the managers to reallocate the critical path or change the course of the work in other activities. All these things affect the project activities adversely and the project gets delayed. To pull it back on track, major overhauling in the schedule becomes necessary.

Changes in the activity schedules of the critical path is therefore a common phenomenon within a CPM. Project managers always keep an eye on its activities and update the path now and then to avoid delays or to accelerate the project. For instance, as William A Manginelli in his article on ‘Schedule Analysis’ of a construction project, explains[1], “as the project progresses, the lengths of the paths relative to one another change. For example, as the steel erection work on the longest path makes progress, the remaining duration of that path becomes less. Conversely, as the masonry work on a shorter path fails to make progress, the remaining duration of that path remains the same. If this condition continues, the day will come when the remaining duration of the masonry work path will equal the remaining duration of the steel erection path. On that day, both steel erection and masonry are concurrently critical. On the following day, the lack of progress of the masonry work begins to critically delay the project.”

To overcome such a situation, constant monitoring of the critical path activities and rescheduling a few other tasks of the project from time to time becomes necessary to avoid delays and restrict losses. In fact, CPM itself is such a tool, which analyzes such an impact of changes on the entire duration of the project from its start to finish. It provides the managers timely guidance to respond to the problems and make changes in the project schedule in the most cost-effective way.


[1] Manginelli, William A. Jan 2007. Construction Update. Schedule Analysis – Cracking the Code. Retrieved at

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