CPM Scheduling - Critical Path Method Scheduling
Critical Path Method (CPM) scheduling is simple and effective. It works on the basic premise that there is one best path to accomplish a task or project by an expected finish date. To do that, the needed amounts of time for each core task is determined and placed end-to-end in the sequence they need to be accomplished, producing a flow chart of the total project.
But there’s more to it. CPM scheduling identifies each step but also takes into account the best-case scenarios, likely scenarios and worst-case scenarios for each step. Take the example of foundation work for a commercial building. In the best case, with the best crew and with no delays for weather, perhaps it takes 10 days from beginning to end. In the worst case, materials aren’t delivered on time, weather interferes, or plans are changed at the last minute, so in that case, the step takes 15 days – costing both owner and contractor time and money because it pushes every other task further down the path unless another task can be compressed.
An experienced contractor can look at the possibilities and probabilities and budget time for the most likely case: 12 days, which allows for any weather-related problems. And if materials are ordered at the right time in the process and there are no last-minute changes, that contractor knows that the crew will finish on time or early, which allows the next task on the plan to be started.
Any major project will have both tasks that need to be accomplished end-to-end and others that can be undertaken simultaneously. Tasks that are interdependent and “critical” must happen in proper sequence; those that can move around without delaying the rest of the project are said to have “total float.” Managing these tasks properly is critical to establishing a realistic on-time and on-budget finish.
Today’s project management software, in the hands of experienced users, works on a CPM basis and can be updated in real time. It is most successful when everyone involved in the project buys into the work plan, from the owner and contractor to the subcontractors and suppliers.
At TD Wilson, we use only the best CPM software tools: Primavera P6 and P3, SureTrak (ST) and MS Project. All are highly rated and capable of delivering comprehensive reports and sophisticated analysis.