How to Perform Effective CPM Scheduling

Experts recommend several tips to ensure your team creates and maintains an effective CPM schedule. Advice includes using appropriate software and ensuring your team understands all dependencies among activities. Also, make sure your team adjusts the schedule as needed.

Here are some top best practices from experts:

• Clearly Define the Scope of the Project: Before your team can start establishing a CPM schedule, they must make sure the scope of the project is clearly defined.
  
  “Without a clearly defined scope, it’s very easy to get off track. And to perhaps identify tasks that do not necessarily apply, but that you think might apply — because the scope is not really clearly defined — when they really don't,” explains Rosalie McGee, Program Management Office Director for Crux, a technology design and consulting services firm for architects, construction design professionals, and facility owners. McGee says those additional out-of-scope tasks “end up adding more time or steps to your project timeline.”
• Use Software or Other Helpful Tools and Allow the Tools to Do Their Work: While it’s good for people to understand how a CPM schedule works, rarely does anyone create a CPM schedule manually anymore. Software — and, in some cases, simpler tools — can create the best schedule for your project.
  
  “The software is fantastic. You only really need to understand what a network diagram is, and why it's important to do a forward pass and a backward pass. But you don't need to do the math calculations in order to figure that out,” OBrien shares. “Don't be too intimidated by the technique behind the network diagram as long as you understand the concept behind it. The software guides you; rely on it to make the diagram.”
• Allow the CPM Schedule to Reveal the Most Important Activities: Your team might have thoughts on what are the most important and critical activities in the project, and assume those will have the most direct impact on project completion. But the software-produced CPM schedule may show that less-notable activities are on the critical path. Your team needs to pay more attention to those activities. 
• Sequence, Connect, and Link All Activities: Every task in a project is dependent on the completion of a predecessor task. Each task has at least one other task that depends upon its completion, or a successor. Your team needs to examine all activities, sequence them correctly, and determine how each connects to others.
  
  “Make sure every task has a predecessor and successor. I've looked at hundreds, or probably thousands, of project schedules across my career, and most of them do not have predecessors and successors appropriately linked,” Zucker shares.
  
  A CPM schedule might require a task to be finished by August 30. But your team might not appropriately link that task to the required completion of a separate task — which won’t finish until September 10. “Since you did not make that explicit linkage, the schedule will no longer coincide with the reality of the situation,” Zucker adds. “The schedule needs to make that linkage.”
• Be Open to Rethinking How Activities Relate, and Rearrange: Ensuring linkages between all related activities might show the project taking longer than expected. Analyzing the linkages carefully can also allow your team to shorten the project. When you understand how certain activities might not have to wait on the completion of other activities, your project team can rearrange work or align resources differently.
  
  “The ultimate lesson is that, after you put together your initial project schedule, you need to look,” Zucker says. “You need to scrutinize it carefully, and ask yourself: ‘Does it conform to the realities of the situation? Are there things that we can do in terms of adjusting our predecessors and successors? Or are there other things that we can manipulate in order to get to a more reasonable date?’”
• Determine Realistic Timelines for Each Activity, and Don’t Force the Finishing Dates: Even if you can do some rearranging to shorten the project, you can’t simply force your team to finish an activity that needs other tasks to be completed first. If the team estimates an activity will take 10 days, you can’t expect the team with the same resources to finish the work in 4 days.
  
  “Don’t force the dates. If you're forcing the dates, it means you're not respecting the information that you're being provided either in terms of the precedence of activities, or the estimated durations,” Zucker says.
  
  Project leaders and team members must provide good estimates of the work required for all activities. They must keep in mind their resources and any risks that could delay any activity.“If you don't look at all of these things at the start of the project, as you're focusing on the critical path, then your plan might look pretty. Actually, you'll run into a whole host of problems in two months' time, six months’ time, and a year's time,” OBrien advises.
  
  OBrien suggests your team considers holidays during the project timeline, including international holidays if you have workers or vendors from other countries. He also recommends using a Program Evaluation and Review Technique (PERT) analysis to get an average of three different estimates of how long any activity will take.
  
  “The PERT analysis is your best friend. Nobody in the software world ever wants to give you an estimate. So the best [recommendation] that I would give on that is that PERT analysis. I wouldn't even consider just asking for one number [for a time estimate to finish any activity] ever again,” OBrien says. “It's a disaster.”
• Review the Schedule With the People Who Will Do the Work: Project leaders need to review the schedule and the estimated time each activity will take with the team members who will be doing the work. “Review it with everybody, and ask the people actually doing the work if it’s correct and reasonable,” Zucker says. 
• Assign a Team Member Responsible for Each Activity: Each activity needs a person or team responsible for its completion. That person or team ensures the activity is completed on time and manages its float if it is not on the critical path. 
• Understand the Resource Limitations Your Team Will Have: It’s vital that your team leaders and members understand any resource limitations, especially when estimating how long each activity will take. There may be times when your organization can add more resources (or crash) to an urgent activity. But that likely won’t happen. Most often, you’ll have to do the work with your available resources.
• Ensure the Schedule Uses Your Resources to the Fullest: The CPM schedule will help you see which activities need which resources, focus on the critical path activities that can’t afford a delay, and inform your team how to use resources most efficiently. You’ll want to align those resources with what the schedule shows you.
• Monitor, Monitor, Monitor: It’s vital that your team continually monitors the schedule and all work in progress. Are tasks being completed on schedule? Do they need to keep a close eye on the status of tasks on the critical path?
  
  “It's really important to monitor your project, pretty much through every stage of the project, and have that clear communication with the team,” McGee explains. “You're monitoring your scope. You’re monitoring that schedule to make sure that we are where we are supposed to be. And then you’re monitoring the budget and monitoring resources.”
• Be Ready to Make Schedule Changes When Needed: As the project moves forward, circumstances will change and affect the work on activities and a range of deadlines. Your team will need to constantly monitor the schedule and make the necessary adjustments.
  
  “Update the schedule on a regular basis because, as we're executing, the actual durations (for activities) may take longer or shorter than planned,” Zucker says. “The critical path of our project may shift accordingly. You need to go through the schedule traditionally every week, and update all the activities in terms of where they are.”
• Be Open to Large Changes if Needed: Sometimes, so much changes in a project that it needs more than minor tweaks. That’s when your project team might need to get into the schedule and make significant changes to activities or the sequence of activities.
  
  “Sometimes items on your critical path get unbelievably whacked out. That’s an opportunity for you to look at the schedule to see if there’s a different way of sequencing the work,” says Zucker.