Construction schedule delay analysis by experts such as The Holloway Consulting Group goes far beyond the analysis of planned versus actual performance. The schedule delay expert peer group in the United States has categorized schedule delay methodologies:
CONSTRUCTION SCHEDULE DELAY | EXPERT ANALYSIS METHODS
Impacted As-Planned Schedule Method
The Impacted As-planned Schedule method was popular in the 60s, 70s, and 80s in CPM schedule delay and impact claims. In this method, delays are developed as unique activities, and inserted into the (un-progressed) contract, baseline, or reasonable as-planned schedule. A schedule calculation is then performed and a new “adjusted” completion date is established. The hypothetical impact of delays on the completion of the work is then portrayed through a comparison of either the original as-planned completion date or the actual completion date, and the new, adjusted completion date.
Global Impact Method
Using this method, delays, disruptions, and similar occurrences are outlined in a narrative text. The start and end dates are determined for each event and the duration of each delaying event is computed. The alleged duration of the delay is often an arbitrary assignment which may not have had any effect upon the project completion date.
Net Impact Method
In this method, delays, disruptions, and work suspensions are typically plotted on an as-built schedule. Change orders are commonly depicted as delays, and every change is alleged to have impacted project completion. With extensive delaying events displayed on the as-built schedule, but without any network calculations, claimants have argued that combined effect of the events has delayed the project.
As-Built But-for Method
With this technique, the as-built schedule is developed in CPM format and excusable and non-excusable events are identified and tied to affected activities. The as-built critical path of the project is then identified to determine which delays, if any, affect critical path activities. After all delays caused by the first party are removed from the analysis, the remaining schedule allegedly depicts the date the project would have been completed “but-for” the delays of the first party.
Collapsed As-Built Method
Using this method, delays, disruptions, and similar occurrences are outlined in a narrative text. The start and end dates are determined for each event and the duration of each delaying event is computed. The alleged duration of the delay is often an arbitrary assignment which may not have had any effect upon the project completion date.
Corps Modification Impact Evaluation Guide EP 415-1-3
The Army Corps’ of Engineers Modification Impact Evaluation Guide (EP-415-1-3) represents a detailed and widely recognized method for contemporaneously evaluating the effects of delays on project completion. This technique has also been used in labor productivity analyses, and shares numerous similarities with the Time Impact Analysis technique discussed below. We have rarely seen EP-415-1-3 used in private contract disputes, which may be attributable to the rigors of the technique and its attendant costs, and we almost never see it used in retrospective analyses.
Time Impact Method
The as-built status of the project, incorporating actual start/finish dates, changes, delays and impacts, is established up to the impact date and the schedule is recalculated. The as-planned or uncompleted portion of the schedule then forecasts the work remaining to be completed. The estimated impact of any delay-causing event can then be assessed by comparing the newly established completion date to the previous as-planned completion date. (Alternatively, the schedule can also be statused after the delay or impact event has been resolved.)
Schedule Update Method
Monthly and periodic schedule updates play an important role in the project management and progress payment processes. In addition, when a time-related dispute arises, schedule updates should become a key part of the process of identifying and quantifying gains and losses to critical path activities during sequential periods of project performance. Ideally, each schedule update will incorporate as-built activity start/finish dates, work sequence changes, logic and duration revisions, and known delays occurring since the prior update. In this manner, the contractor contemporaneously creates an as-built schedule during the project that allows it to more accurately schedule and complete the remaining activities.
Window Analysis Method
As originally defined, window analysis focused on an analysis of as-planned versus as-built “critical path activities” within sequential time periods of the project.
