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Kenneth R. Baker, P.E.
Trauner Consulting Services, Inc.
San Diego, CA


An overview of the concepts of delay analysis and a brief discussion of delay analysis methodology is presented in this paper.

The technical side of delay analysis is detail-intensive work that uses terms and concepts unfamiliar to many potential audience members such as jurors or mediators.  In delay analysis presentations, however, it is imperative to convey the delay analysis and findings simply and clearly to that same audience.  Unfortunately, some experts will employ analysis methods that are easy for the audience to understand but, when de-constructed and studied in detail, the analysis will contain major flaws and be distorted by assumptions and subjectivity.  The most successful and valuable experts will perform the delay analysis using a sound methodology and then develop a presentation of the analysis and findings that is compelling, yet easy to understand. 


Delays can be categorized into the following types:

1.      Critical and Non-critical

2.      Excusable and Non-excusable

3.      Compensable and Non-compensable

In order to determine if a delay is critical, an understanding of some basic scheduling terms and concepts is needed.  A critical delay is a delay to an activity that will cause the project completion date to be delayed.  A delay is critical only if it extends the duration of work that is on the then-prevailing critical path.  The critical path is the longest continuous path of work that establishes the project completion date.  The activities on the critical path do not have float.  Float is defined as the amount of time between when an activity could start and when it must start to avoid delay to the project completion date.  Thus, the analyst’s job is to systematically determine with objectivity the delay issues that affected work activities on the critical path.  To accomplish this task, the analyst will work through a myriad of delay issues to determine which issues delayed the critical path work, or delayed non-critical work to the extent that all the available float for the activity was expended causing it to become critical.

Review of the project contract documents will often establish which delays are considered excusable or non-excusable.  Typically, delays caused by unforeseen events beyond the control of either party, such as extreme adverse weather and strikes, are classified as excusable delay.  In cases such as these, absent contract language to the contrary, neither party is at fault for the delay and the owner should grant a time extension if the contractor follows the prescribed procedure to request one. Non-excusable delays are those that are the contractor’s responsibility.

The project contract documents will also usually establish which delays are compensable or non-compensable.  Compensable delays are excusable delays for which the contractor is entitled to additional time-related compensation.  Subject to the contract language, the contractor is typically entitled to the labor, material, and field office costs associated with the delay period; and may, in some cases, be entitled to additional home office overhead costs.


All delay analysis techniques are most often a variation of one of the following five methods:

1.      Impacted As-Planned

2.      Collapsed As-Built

3.      Windows Analysis

4.      Contemporaneous Analysis

5.      As-Built Analysis

Each of these techniques will be briefly discussed in the paragraphs that follow.

Impacted As-Planned

The impacted as-planned (IAP) method makes use of the schedule that was created at the start of the project – the as-planned schedule.  The analyst inserts delay activities into this schedule to allegedly represent the impacts to the work caused by the particular delay events.  These inserted activities cause the project completion date to be extended.  This is taken to be support for the number of days of delay and entitlement for additional costs.  Most construction industry professionals and third-party venues have agreed that the IAP method is not an accurate method to quantify the impact of delays on a construction project.  The IAP method disregards all of the as-built project information.  It also affords the analyst great latitude to select what issues to address or overlook.  This provides additional opportunity to manipulate the results of the analysis.

Collapsed As-Built

The collapsed as-built (CAB) method is similarly flawed.  The CAB method, also referred to as a “but for” analysis, gives the analyst great latitude to manipulate the analysis to produce the desired results.  An attractive aspect of this technique is the use of an ‘as-built’ schedule as the starting point for the analysis.  The project records are used to establish the start and finish dates for the activities shown in the ‘as-built’ schedule.  This wealth of factual documentation, often in the form of daily reports, meeting minutes, letters, and photographs, lends the impression of validity to the analysis.  The first major opportunity for manipulation comes in the analyst’s creation of logic relationships for each activity.  Next, the analyst identifies particular delay events, retrospectively creates ‘fragnets’ to represent those delay events, and then removes the fragnets from the ‘as-built’ schedule, to show the improvement to the project completion date “but for” the delay issues.  The CAB method is highly subjective because the analyst creates the as-built schedule, assigns preferential logic, chooses the delay issues to address, creates a ‘fragnet’ to represent those issues, determines how those ‘fragnets’ tie-in and affect the work, and then removes the delays in some chosen sequence.  The choices made by the analyst in these areas largely determine the results of the analysis.

Windows Analysis

The windows analysis method (WAM) organizes the events that occurred on the project into specific, analyst-defined time periods.  A major shortcoming of the WAM is that the analyst’s selection of the analysis time period, or ‘window,’ is subjective and materially affects the results produced.  Another shortcoming of the WAM is that although various methods of analysis can be used within the window time period, all versions are generally referred to as a windows analysis.  The WAM can also fail to consider and address out-of-sequence progress or delays that occur outside the ‘window,’ which may be the real cause of the project delays.  Again, the choices made by the analyst in these areas materially affect the analysis and can largely determine the results.

Contemporaneous Analysis

The contemporaneous analysis is usually the preferred method of analysis.  The monthly project schedule updates that were produced by the project participants are used. The critical path of a schedule is compared to the critical path of the schedule from the preceding month.  The analyst tracks the day-to-day progress of the activities on the critical path from month to month and records any delays or savings.  This method produces a specific identification of the activities causing delay to the project completion date from the beginning to the end of the project.  Since the analyst employs the schedules created and used by the project participants, the method is less susceptible to analyst manipulation.  The method does require project schedules that were updated regularly and reasonably accurately during the course of the project.

As-Built Analysis

The as-built method of analysis differs from the previously mentioned CAB method.  The as-built method is typically used when detailed project schedules do not exist, or they exist but are flawed to the extent that they cannot be relied on to support the delay analysis.  The project documents are used to establish a detailed record of the as-built work.  The analyst has the responsibility to identify and document any revised logic from the as-planned sequence in the as-built work.  Delays are determined in a sequential manner through comparative analysis of the critical as-built work to the critical as-planned work.  The as-planned schedule dates are updated to recognize the chronological impact of each delay in turn.  In the event that no reliable as-planned information exists, the analyst will identify critical delays by comparing the as-built information to a retrospectively developed plan that allocates the overall project duration into reasonable time periods to accomplish the major work tasks. The successful use of an as-built analysis requires an analyst very experienced in construction means and methods making choices that are transparent, documented, and supportable.


Although many methods of analysis are used to determine delays on construction projects, one of the five basic approaches outlined in this article is usually at the heart of these methods.  Many of these approaches are prone to manipulation and can produce favorable results that are pre-determined and controlled by the schedule analyst.  In evaluating delay analysis presentations, third parties need to have a basic understanding of the assumptions inherent in the delay analysis methodology used and they must carefully examine and question analyst-driven decisions in order to identify subjectivity and manipulation that affects the findings.

About the AUTHOR

Kenneth R. Baker, P.E.
Western Region Vice President
Trauner Consulting Services, Inc.
3111 Camino Del Rio North – #1350
San Diego, CA 92108-5720

Ken Baker is the Western Region Vice President for Trauner Consulting Services, Inc., a consulting engineering firm with offices in San Diego , Boston , Orlando , and Philadelphia .  He earned his undergraduate degree in civil engineering, with honors, from the University of Massachusetts .  He earned his M.B.A. degree, with highest honors, from the University of Denver .  He is a registered professional engineer in Colorado and a B-licensed general contractor in California .  Mr. Baker has been in responsible charge of design, construction, and consulting work for some 34 years through the operations, management, and consulting positions he has held with five firms.  Mr. Baker’s clients include federal and state public agencies, private owners, sureties and insurance companies, general contractors, subcontractors, and attorneys.  His expert witness and dispute resolution work for these construction clients is in the areas of CPM scheduling, delay analysis, lost productivity evaluation, disputed extra work, specification interpretation, claim damages, design build and construction management professional practice.  Mr. Baker’s construction project experience includes hotels, casinos, schools, power generation facilities, industrial plants, roads and bridges, parking structures, hospitals, prisons, hi-technology and bio-technology laboratory facilities, low-rise and high-rise commercial buildings, and land development projects.  Mr. Baker’s lectures, seminars, and technical training programs have been attended by more than 1,000 industry professionals throughout the United States .

This article is published in Report, Vol. 9, No. 1 (January, 2007).