Keep it simple – An introduction to delay analysis

As planning and delay professionals, we are often asked if we believe that delay analysis is as complicated as what other professionals say and some, even sarcastically, ask if delay analysts have a magic box to keep the black art of delay analysis in… the simple answer is NO to both questions!

On a more serious note, the key to delivering any successful delay analysis is the selection of the most appropriate methodology and upon selection and execution of the analysis being able to simplify the results and present the findings.

Methods of Delay Analysis

Delays are often complex issues that require a clear and objective opinion on the areas of contention and at the Iain Wishart group we like to make the analysis, explanation, and demonstration as simple as possible. Over the course of this article, we examine the process of analysing delay in greater detail.

Whilst the delay analyst has several different methodologies and often has a preferred choice, we believe the key to any successful delay analysis is dependent on several factors which normally relate to:

• The terms of the Contract;

The availability of appropriate programmes (i.e., baseline or contract programmes);

• The as-built data – i.e., the contemporaneous progress information;

• The nature of the delaying events; and finally

• Records to substantiate the delays.

Prior to selecting a delay analysis method, one of the first tasks of the delay analyst should be to arrange a workshop with the Client’s team and subject to the type of appointment, the Client’s legal representatives.

During the workshop, it is important to:

• Identify what programming data is available, including in electronic format.

• Identify the progress failures i.e., the possible claim headings.

• Raise questions and discuss the progress failures.

• Identify the project records that support the progress failures and those most likely be used to support the delay analysis and the drafting of the analysis.

• Seek Client input and request clarification and further supporting documents.

    • At this stage, it is key to take a step back and assess the situation and look at the strategic positioning that may be required, such as preparing a document for the purposes of negotiation; mediation; litigation; Dispute Adjudication Board / Dispute Review Board or arbitration.

• Upon completion of the workshop, it is important to understand what information is available or not as the case may be before requesting any further particulars and moving to selecting a method for the delay analysis.

Choosing a method of delay analysis can be a relatively simple process if the steps outlined above and input are undertaken to the required detail and in doing so, it allows the delay analyst to review the available records and the requirements of the appointment before looking to select the most appropriate delay method.

A delay analyst has several widely used methodologies or techniques that they can adopt and in our opinion, the five most widely used and recognised methods of delay analysis are:

• A comparison of as-planned with as-built;

• An impacted as planned;

• A collapsed as built;

• Time impact analysis; and

• Time slice or Windows analysis.

As Planned versus As Built

This method of establishing delay to completion is based entirely on the factual history of the project and is therefore a retrospective method of delay analysis.

It is most commonly used after completion of the project as the factual history should be complete. Additionally the methodology can also be used for determining liability for a delay at a point part way through a project.

To add substance to an analysis and assuming the programme is logic linked and available to the delay analyst, it is often common practice to compare the planned critical path against the actual critical path. This allows the delay analyst to determine which of the project’s activities were programmed to be driving and which were actually on the driving critical path.

Impacted As Planned

The impacted as-planned method of delay analysis is a theoretical static method of delay analysis generally relying on a single as-planned programme. The programme used is typically the tender or master programme (planned baseline).

Representations of delay events are added to the planned baseline programme to demonstrate the effect on the completion date. This technique does not consider the actual delays or actual progress as at the time of a delay event, nor does it take into account any concurrent delay and / or acceleration.

The impacted as-planned method assumes that the as-planned logic and the as-planned durations are accurate, and the Contractor would have strictly followed the as-planned logic. For these reasons, this method is not favoured by the Judiciary or Tribunals as it is considered a hypothetical or theoretical view of any possible entitlement.

Nevertheless, in the absence of comprehensive as-built information or insufficient progress records to allow an as-built programme to be reconstructed, the as-planned method may be the only technique available to the delay analyst to ascertain the effect of delay.

Collapsed As Built

The as-built but for, which is also known as the collapsed as-built delay analysis methodology, relies on an as-built programme from which relevant delay events are defined and then subtracted, to determine when the works could have been completed, but for those delay events.

The method can be used separately for the Employer’s Events and the Contractor’s Events which provides a balanced view of delay and assists in highlighting concurrency and parallel delays as well as ‘neutral’ events.

For the methodology to be effective, it is essential that the as built programme be fully logic linked and workable, which can introduce an element of subjective judgement into the analysis in that this is done by an analyst after the project is completed.

The methodology is a wait and see approach that is used retrospectively, and generally, after completion. However, it does not reflect the dynamics of programme change during the construction lifecycle. Whilst the methodology is based on fact, its application can be subjective to how events are removed and does not account for any pacing of the works that might have occurred.

Time Impact Analysis

Time impact analysis is essentially a prospective technique that predicts likely future delays. It involves taking a snapshot of the programme status immediately prior to the occurrence of a delaying event and then impacting the event onto the planned programme that has previously been updated with the progress achieved at or as near as possible to the time of the event.

The activities that have been progressed will represent the as-built history of the project, whilst the prospective activities represent the work that has still to be undertaken providing a realistic programme through to overall project completion.

The alleged delaying event is then incorporated into the programme to reflect the direct impact of the event to see the effect primarily on the earliest completion date of the Works or Works Section as calculated by critical path analysis of the remainder of the amended programme.

This simple contemporaneous approach to delay analysis allows an assessment to be made of three important aspects, which tend to be unavailable with other methods such as as-planned versus as-built, impacted as-planned and collapsed as-built:

1) The actual state of progress at the time the delay event was initiated;

2) The changing nature of the critical path because of delays to progress and / or acceleration; and

3) The concurrency of delays to progress and to completion.

A note of caution, time impact analysis can be difficult to carry out and its presentation can become complex if there are multiple delay events involved.

Time Slice Analysis

Time Slice or the Windows method of delay analysis, is used for identifying the periods when critical delays occurred to the project. This method is a prospective method of delay analysis based upon contemporaneous information that can be used in retrospective delay analysis.

The methodology so named as it involves breaking down the project’s duration into several sequential periods called windows or time slices.

A variant of the Windows method is the watershed method, which consists of analysing periods of the project with irregular durations determined by the delay analyst to represent the stage of the project to be analysed.

By example, the analyst may choose to analyse all the delays to the substructures in a single watershed even though the duration of the watershed may span several months.

A Windows analysis has the benefit of assessing any delays in smaller manageable chunks than would be the case if the analysis was carried out on the entirety of the project, this makes the analysis less complicated and therefore easier to understand.

The Windows technique additionally allows for an analysis of subsequent revisions to the baseline programme to reflect any changes to the programme as it develops.


At the Iain Wishart group, we do not have a preferred methodology and do not believe there is a one fit method for analysing or demonstrating the delays that have occurred to a project.

The contract documents; available electronic programmes; supporting records; the nature of the delaying events; the time frame and cost constraints to complete the analysis, are all critical decisions that require careful consideration and thought before selecting the appropriate method of delay analysis.

In summary, in order to select the most appropriate method of delay analysis, sufficient preparation time must be given to:

i) Review the available programmes and records;

ii) Seek input from the relevant project parties;

iii) Understand the objectives of the delay exercise; and

iv) To remember the words of Albert Einstein…

“Everything should be made as simple as possible, but not simpler.”

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