Comments on the CPA MethodThe CPA (

Comments on the CPA Method
The CPA (windows) method is
often the most time-consuming
schedule delay analysis method.
However, it can be very accurate,
and has the potential to be the least
controversial and the most analytical; it can be equitable to all parties.
The windows method puts all delays
in the context of the time, place,
and circumstances of the project as
revealed in the contemporaneous
documentation for the window period. This places an added burden on
the analyst to review all significant
and relevant documents or risk losing credibility. The windows method is an accepted way to analyze
schedule delays for trial or arbitration testimony, especially in the federal courts.
Like other evaluation techniques, CPA is seldom as easy as it sounds and should not be performed without using careful analysis and sound judgment. The sched¬ule updates generated during construction should not be used until the information contained in them is verified using other project documentation [6].
Current cases indicate that the courts will not uphold a windows analysis that is based only on questionable schedule updates. In a recent case, the Board of Con¬tract Appeals said the following:
[the] respondent’s CPM expert was recognized by the board as an expert in scheduling analysis and the review of planned sched¬ules. [He] employed a contemporaneous time frame analysis to evaluate the delay on this job . . . [he] divided the work into 17 windows. The critical path used was that shown on Cogefar’s schedule updates. [He] then performed an analysis on each window determining whether Coge- far or the FBOP was responsible for the delays. [He] admitted that, while Cogefar changed the logic
in its December 21, 1992, schedule, he did not use this change since the FBOP had rejected that schedule . . .
[he] failed to use a current CPM schedule to evaluate the delay on the project. This is mandatory to achieve an accurate assessment of whether an item of delay affects the overall completion of the project [2],
According to Lee Schumacher,
In most cases, an as-built schedule based on the entire written record should be de¬veloped to add credibility to information contained in the contemporaneous schedule updates, and if necessary, modify them to more accu¬rately describe the status of the construction at the time of the update. Care must be used not to make modifications based on hindsight.
The absence of schedule updates, in itself, does not prohibit the use of CPA. The as-built schedule, in conjunction with the reasonable as-planned schedule, can be used to recreate schedule updates as if periodic updating had been performed during construction. Good judgment is especially important in this type of evaluation. When recreating the schedule updates, it is extremely important that your expert bases the schedule status solely on information that was available at the time. Critical path method schedules or complex construction projects can contain thousands of work activities, but generally there are relatively few that dictate the critical path in particular discreet time periods [6].
The beauty of CPA is that it can divide these complicated schedules into “digestible portions.”
Equally important, this daily evaluation technique identifies and presents the critical delays in chronological order as the project unfolds. For these reasons, it is easy to understand. In addition,
CPA recognizes the concept of float as a resource to the project and facilitates the distinction of actual delays from apparent delays caused only by the pace of the project [6].