6 Reasons Critical Path Schedules Fail – Part 1

6 Reasons Critical Path Schedules Fail. Without good CPM schedule maintenance throughout the course of a project, the investment of time spent in developing a good baseline schedule will be largely wasted, as the schedule will become increasingly unreliable as a project management and delay analysis tool. In the last newsletter we looked at how not to create a CPM schedule; this time we will look at how not to maintain a schedule as the project unfolds.

1. Infrequent Maintenance

Good maintenance needs to be regular and frequent. Just as your car needs a regular oil change and tune up to stay at peak operating efficiency, your CPM schedule should be updated once a week, or every other week at the latest. Unfortunately many project managers get so busy with the daily details of running a project, from paperwork and inspections to managing subs, that it is easy to procrastinate here. Oftentimes contractors update the schedule only because, and not until, the owner makes them or they need to file a time impact analysis. Usually that means that a month or more lapses between schedule updates. By that time, the project manager has forgotten many of the specifics and, not wanting to take the time to look up the details in the daily reports, guesses at everything, which leads to bad data (see point two below) and a failure to note and track the impact of delay issues as they arise (see point three below).

Best practice is to examine three- to four-week short-range look ahead schedules on a weekly basis, compare them to the last month’s schedule update or approved baseline, and pay close attention to any activity that is critical, near-critical, or that has slipped considerably against the comparison schedule. It is easier to maintain a schedule if you do it regularly, and the very activity of maintaining it will remind and alert you to possible project issues.

2. Bad Data

When it comes to updating a schedule, one of the easiest and most common things to do is to plug in a few actual dates and completion percentages—often just rough guesses from memory—check the resulting milestone dates, and run with it if the dates look acceptable. The problem with this practice is that the schedule can very quickly become filled with bad data and bad logic and cease to be a useful project management or delay analysis tool. When statusing a schedule it is important that the information entered be accurate. Frequent maintenance helps here. Also, the logic of the work especially that of critical or near-critical activities, needs to be reexamined periodically. We suggest once a month at a minimum.

3. Failure to Track Delay Issues As They Arise

When delay issues arise—such as a late response on an RFI, inclement weather, utility conflicts, or what have you—a common practice among schedulers is simply to add a log entry on the impacted activity. This is fine, but it doesn’t show you what impact the delay will have on the critical path. To see that you need to add the delay as a separate activity and tie it in to the rest of your schedule. As soon as feasible after a delay issue emerges, you should start tracking it in your schedule so that you can forecast its impact and make appropriate project management adjustments. A further advantage is that if the delay becomes a claim, you will already have a good documentary history in your schedule of its impact on the job. This is much simpler than trying to retroactively plug a delay into a completed as-built schedule in order to determine its impact.