Top Ten CPM Scheduling Mistakes

As experts on construction delays and presenters of critical path method (CPM) training, the authors of this paper regularly get the opportunity to review a variety of project schedules. What the authors find is that good schedules are essential to reliably completing construction projects profitably and on time. If they’re used, they make every project manager better, even those that think they don’t need a CPM schedule. A good schedule provides other benefits. It allows time to be measured accurately. That means agencies and contractors don’t have to fight about the delay associated with a change. They can accurately evaluate the time lost to a problem and determine the time extension due, if any, when the problem occurs; they don’t end up waiting until the end of the project and dealing with the problem as a claim. In fact, not only is a good schedule a good way to measure delays, in many contracts, it’s often the only way to measure time and prove entitlement to a time extension. As one federal judge said, “The parties will ‘live or die’ by the contemporaneous project schedule.” The problem arises when the CPM schedule put together for the project doesn’t accurately communicate or doesn’t accurately match the contractor’s plan. Many contracts require CPM schedules and when they don’t, many contractors have been convinced of their effectiveness and use them anyway. After looking at hundreds of schedules on almost every conceivable type of project we have compiled a list of common mistakes. These mistakes hurt a project in at least two ways. First, because the CPM schedule is, or should be, used to administer the work, mistakes may cause the project team to focus resources in the wrong place at the wrong time, or prevent the parties from accurately assessing whether the job is ahead or behind schedule. This potentially reduces everyone’s efficiency, increases costs, and reduces profits. Second, if there is a delay that leads to a dispute, the errors in the schedule may lead to disagreements and claims regarding what work activities actually delayed the project and by how much. In today’s construction environment one of the most daunting risks faced by the project team is delay. While owners and contractors both recognize the costs of delay, and agonize over the specter of litigation, delays can be avoided or quickly and amicably resolved through the use of good scheduling practices.