Delay Analysis
Remember that turning the titanic once it's on top of the iceberg may not keep the boat from sinking. If you see a delay, you should try to resolve it as quickly as possible. If you get involved in the project once the delay has set in, all I can say is I hope you are getting the "Mr. Fix-It" bonus.
Chances are things will not go as planned on your projects. That's okay because that's why they have to hire you, right?! CPM provides some tools to help you determine what went wrong and what you can do about it.
Prerequisite: Good Schedule and Records
Your analysis of project delays is contingent upon having a representative schedule that includes all significant features of work, identifies the subcontractor or partner responsible for the completion of the tasks, identifies non-work activities, and shows work areas through which the crews must complete their efforts. The schedule will have had to be updated during the project to accurately reflect progress and include any change orders that occurred. If your schedule does not include these features, you may as well get out your checkbook and call the consultants and the lawyers to fight it out in court for you... sorry, but sometimes there is no "easy button". If you have a good schedule and a complete set of records for the project, here's what you do…
Step 1. Review Critical Path(s)
The Critical Path Method is, by definition, a model that helps the team to identify those paths through the network that govern the duration of the project. As a result, the first step in the evaluation of any delay is to identify the network paths that lead to and follow from the current schedule snapshot. Practically speaking you will need two reports to perform path analysis: a total float report and an activity logic report.
Using The Total Float Report
The total float report lists activities in ascending order of their Total Float. The sub-sort for this reports should be Early Start. In-progress and future scheduled activities on the same path will have, by definition, the same float. As a result, if there is a single critical path, all those activities will appear together at the top of the report. In this report you will, most likely, be able to easily identify several paths through the network simply based on the shared float value.
Using the Logic Report
To verify that there are not multiple activities with the same float, or to evaluate the potential impact of intermediate milestones that could have affected the schedule calculations, you will also need the logic or sequence report. This report will show each activity and list each of its priors' or successors'. This report should list all activities, including those activities that have been completed. With this report you can verify that a set of activities on the critical path (or any other path) are in-fact members of the same path. Also you will be able to use this report to identify those completed activities that may have contributed to the delays currently reported by the schedule.
Step 2. Find the Culprit(s)
It is with particular care that you will need to look at previously completed activities. This is because it is those activities in the past that planted the seeds of your current delay. If you are able to identify and document the cause of these delays you will be able to resolve whatever issues were the cause of the problems that much more quickly. Waiting until the end of a project to find out why you finished late is no way to run a project. Waiting until after the project means that lawyers and consultants will have to figure these delays out for you and eat into your compensation (and more importantly take your attention from pressing needs on current jobs). Finding out the cause for the delay during the project allows you to make adjustments and when appropriate receive compensation for delays caused by others.
Okay, so you should start by looking at the activities that are completed. Determine which of these activities (1) started later than originally planned and/or (2) took longer than originally estimated. These are the only two conditions that will result in delays in the CPM model, so this must be your first focus. In addition to the total float report for the current reporting period, you will need to go back to the previous schedules and look at their total float, or other progress reports, that showed activities' actual start dates, remaining durations, and actual finish dates. These prior reports will help you identify the time periods during which activities were affected by various types of delays.
You are acting here as a "forensic scheduler." Your concern is with identifying the problems that have occurred in the past. We will discuss what to do with your findings after you have drawn conclusions about the root cause(s) of any delays you find. Here are the questions you will need to find answers to:
- What is the difference (often called "variance") between original planned dates and the actual start or finish dates. If there is a variance on one activity in a path, the entire path should be marked for evaluation.
- Was the delay to the path of activities a single delay or were multiple activities affected by the delay?
- Since multiple paths (not all of which are the critical path) may have been affected by the delay, extend the analysis to all paths that have experienced schedule variance.
Step 3. Determine the Cause(s)
At this point you will have a set of activities with known delays. These activities should be organized by the path(s) to which they belong. You can now dig into these activities a bit more by considering the following types of questions:
- Material procurement delays may be identified by a onetime occurrence, several delays with the same type of material, or a delay with all procurement leading up to a specific activity.
- Subcontractor delays may be identified by identifying the performance factors by subcontractor responsibility codes.
- Weather delays may be identified by delays of similar activities along several paths through the schedule during discrete periods of time.
- Productivity delays may be assessed by determining the projected man-hours per day to man-hours spent each day.
- Delays associated with specific changes to scopes of work or site conditions must be verified with the site superintendent and quality control officer.
- Delays associated with work due to re-work should be of concern unless that re-work was directed by the project owner.
Clear and complete documentation of these delays will be an important part of your being able to convince others of the accuracy of your analysis. If you are working with an attorney or consultant, your direct understanding of these issues is important since you, and your staff, may be asked to testify about these delays.
Step 4. Determine the Pattern(s)
While historic analysis is great if all you are going to do is go to court, the CPMTutor's goal is to help you get the project back on track. To do this you need to determine if there are any patterns of delays. As you look at the different delays try to see if there is a pattern of delay associated with specific crews, types of work, or work areas. With these you can adjust future durations to determine the full impact of the delay.
Step 5. Predict the Impact(s)
It is important to recognize that delays in the past can be predictors of the events of the future. Unfortunately the way that most people do this is incorrect. Considering the following story:
"A mid-rise building is about 50% complete and 2 weeks behind schedule. The owner says that the contractor must determine a plan for making up 2 weeks in the critical path. The plan is submitted and the work proceeds, the next month the project is an additional 1 week behind schedule. At this point the owner and contractor scratch their heads and try to make up another week. So something is clearly wrong."
Many of us have come across projects that seem to get further and further behind the longer the project goes no matter what we do. This, in many cases, is the result of an error in thinking about the type of delay we have encountered on the project. A point delay may be fixed by simply making up the equivalent time. A productivity delay, however, will not be resolved until the work is completed or the source of the productivity delay is fixed. Let's revisit our story above from newly acquired idea of a productivity delay...
"A mid-rise building is about 50% complete and 2 weeks behind schedule. The owner says that the contractor must determine a plan for making up 2 weeks in the critical path. The contractor identifies that the source of the delay is with the electrical rough-in activity. If nothing is done the contractor can predict that a similar delay on all future electrical rough-in will delay the entire project (if nothing else goes wrong), by 6 weeks. Rather than take the delay the electrical subcontractor is directed to bring more staff on the project both to make-up the time on the current activity but then to keep some of that staff on for the duration of the project to ensure that future electrical rough-in activities maintain their production rate."
With that motivating story, the pattern of delay that you identified must be evaluated to determine how these delays may affect future activities. To begin to evaluate delay, you should consider answers to the following types of questions:
- the rate of float consumption should be identified
- the rate of duration used per period should be identified
- determine if the delay is likely to continue. If it is then apply the rates to similar activities that use the same crew or subcontractor
- activities do not need to be revised based on positive rates of consumption
- activity durations should be adjusted based on the negative rates of productivity
Step 6. Recovery Plan
Knowing the problem is the most important step in figuring out what to do about it. So, now that you know what the problem is, that provides the clue about what to do to fix it. Here are some suggestions about where to find opportunities for making up lost time.
- analyze activities with remaining duration greater than 20 days to see durations may be shortened,
- Activities of similar type should show consistent productivity rates
- determine if sequential critical activities can be performed concurrently
- perform cost/time trade-off analysis
- attempt to accelerate prime contractor work before evaluating subcontract work
Conclusion
If the techniques above are used consistently you may not be able to keep a project from going bust, but you will have the information you need not to have to spend months of time sifting through boxes of project records, or paying someone else to do it, in support of litigation. The saying "failure to plan is planning to fail" has never been more true of situations when the project goes south and your attention turns from getting more business and finding new high-quality clients to picking up the pieces of busted projects.