The critical path method is an essential tool for construction project managers. It helps them track and control construction schedules, ensuring projects are completed on time and within budget. The method involves breaking down a project into construction activities that have fixed duration and precise precedence relationships.
Then, each activity is given a unique identifier and its dependencies are established. This information is then used to create a network diagram, which illustrates the order of each construction activity and its relationship with the other tasks in the project. It is possible to hand draw a network diagram, but there are also software programmes that will perform the needed calculations without referencing a graph.
Once the network has been created, it is possible to identify the critical path. This is the longest path of activities that can be traced from the starting date of a particular activity (or progress data point) to its completion. The critical path typically comprises the activities that have a zero or negative total float value, meaning that if one of these tasks is delayed, any subsequent activity will be delayed too as they all have an dependency on it.
When a construction project manager uses CPM techniques, they can examine the critical path and find ways to improve its efficiency. For example, a chemical producer might notice that job d has a lot of float and that they could cut the length of the job by two days by assigning more carpenters to it. This would result in the critical path shifting slightly, passing through jobs f and g instead of d.