Studying critical path delay and recovery strategies in your schedules is critical for project management. Historic Critical Path Delay measures the number of calendar days a project’s end date is delayed due to impacts on the critical path. By definition, anything delayed on the critical path delays the end date of a project. By studying critical path delays throughout a project’s lifecycle, you can determine what drove the project’s end date back. Then, you can develop a plan to recover against any crucial delays by fixing problems along the way.
To begin doing this, your project team must determine the best way to track, monitor, and quantify critical path delays. Doing so saves ample time in the long run and empowers project teams with the information they need to recover. There are several industry-accepted ways of conducting critical path delay analysis. AACE lists several delay methodologies that you can review to decide which works best for you and your organization, which are summarized below.
Delay Analysis Table
| Definition | Risks | |
| As-Planned vs. As-Built | Compares the final “as-built” schedule to the original baseline schedule | Runs on the assumption that the baseline schedule was static and unchanging, analyzing a high risk of being inaccurate with potentially subjective findings. |
| Collapsed As-Built Methodology | Takes into account all changes in the schedule from the beginning of the impact period through the end of the project, then reverts all changes to the baseline schedule for analysis. | Runs on the assumption that all changes to the schedule are accurate and reflect reality; Requires a project to be finished before analysis; Heavily contested in courts, used to discredit the party deploying it. |
| Time Impact Analysis (TIA) | Inserts a series of activities representing delays and impacts into the schedule to quantify the delay, either prospectively or retrospectively. TIA works if delayed activities are tracked to completion before the delay is quantified and approved. | If conducting this analysis prospectively, the delays haven’t happened yet, making the analysis subjective and, therefore, arguable. If performed retrospectively, this method may assume that the “as-built” data reflects what was known at the time, thus misrepresenting delay.
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| Window Analysis | Delay is analyzed between two successive updates, using an as-planned vs. as-built approach but accepts changes in the second update as the basis for the analysis in the next period, or “window.” | If there are elevated levels of accepting changes to the schedule, then it can be rendered unrealistic due to the likelihood of skewed results. However, this approach is the industry’s most accepted methodology. |
Collaborate Over Critical Path Delay
Using CPM analysis properly, you can track activities to completion and analyze the impact of the delays in each update period using the Windows Analysis technique. If something is critically delayed, it is recommended to quantify the delay. This involves noting the impact caused to the critical path as well as determining causation in real-time. That way, two years later, you won’t be scrambling to find which event caused the project to go off course.
Regardless of which delay analysis method you use, it should always be a collaborative process. This process involves discussing delay monthly amongst project stakeholders with accuracy and transparency. Monthly meetings can be straightforward. Here is my recommended approach:
- Update and analyze the schedule for delays and impacts.
- Look at planned versus actual progress before the monthly meeting without making any changes to the schedule.
- Present schedule findings and discuss them with all parties
- Discuss schedule changes and mitigation or recovery strategies.
- Once agreed upon, incorporate these changes into the plan moving forward.
The meeting should be transparent regarding changes to the proposed schedule, especially regarding changes that mitigate historical delay. With all of the unforeseen delays impacting the construction industry today, discussing and studying critical path delays through analysis and collaboration may be the only way to save a project from heading to the point of no return.
Studying Critical Path Recovery
Critical path delays happen.
The critical path is dynamic, and re-prioritizing resources is usually needed to get projects on track. Modifying the go-forward plan as part of the scheduling process achieves this goal.
However, making changes to overcome historic delays typically compresses the go-forward plan. These changes usually involve changing logic, durations, and even entire calendars. Changes like this risk schedules becoming overly optimistic and potentially unachievable. And unachievable plans often lead to more delays, overruns, and, ultimately, disputes.
Because of this, stakeholders must study recovery efforts built into the schedule. This process encompasses looking at how project schedules are changed to meet contractual deadlines. Studying recovery at every update shows what recovery methods work and which cause more problems than they are solving.
Studying Schedule Changes for Recovery
Things change as projects progress, as does the critical path. Project teams must note how these changes affect the critical path after every update to manage resources effectively. Knowing when critical shifts happen means you can ensure activities are getting done on time.
Here’s how to do it. When studying schedule changes, you need to bucket them into three categories:
- Critical Changes: Studying changes/recovery on the critical path is necessary as the recovery mode may change the critical path completely. The critical path is where you must prioritize your resources, and studying the changes there is crucial for successful decision-making. This is also the path where changes impact the project’s end date most.
- Near-Critical Changes: Near-critical paths should be treated as critical because they can quickly become critical over time. Often, critical path changes pull the end date so far back that the near-critical path becomes critical.
- Non-Critical Changes: Typically, non-critical changes do not impact the project’s end date. However, if changes to critical and near-critical path activities cause acceleration, non-critical activities hop onto the critical path When studying recovery efforts, these changes are typically the last area of focus.
After deciphering what changes occurred within the schedule, begin quantifying these changes using a half-step methodology. The half-step methodology shows where the critical path was before the changes. Understanding where the critical path lies is crucial for allocating resources and staying within time and budget parameters.
Qualifying Schedule Changes with Half-Step Methodology
Half-step methodology distinguishes past performance delays with the responses to mitigate the risk involved in schedule changes. It is a process that updates the schedule with no changes and then compares a schedule inclusive of any future changes. Here is how you do it:
- Step One- Save a copy of the previous schedule update. Add “actual” dates and percent completes for all activities that progress in the period. Do not change anything. Save this file as the half-step schedule.
- Step Two- Create a copy of the half-step schedule. Impart recovery strategies and any other changes necessary into this version. The new schedule will be inclusive of all changes and serves as a contemporaneous schedule update.
- Step Three- Compare the end dates between the “half-step schedule” (step 1) and the contemporaneous schedule update (step 2) to calculate recovery.
What Information Does Half-Step Methodology Provide?
If the critical path and end date changed between the contemporaneous schedule and the half-step schedule, then the date changes result from the changes in the period in question. This process is also used to quantify delay by comparing the end date in the previous update and the half-step update. It also enables an understanding of the result of recovery by comparing the change in the projected end date and the critical path between the half-step schedule and the contemporaneous update.
Project teams must emphasize studying critical path delay and recovery to understand what the true critical path is as part of their schedule control process. If done correctly, studying critical path delay and recovery across your project portfolio monthly minimizes the risk of delays and disputes.
