Delay Analysis Methods – Factors to Consider

Aston Melbourne’s Yazeed Abdelhadi, specialises in delay analysis and has begun writing a series of industry thought leadership articles. This second article below expands on the items listed in the first article and in turn, starting with the factors influencing the selection of the delay analysis methods. 


In my last July 2021 article[1], I provided an overview of the common delay analysis methods used in the construction and engineering industries, along with a brief review of the developmental history of AACE’s recommended practice 29 (AACE RP-29R-03)[2] and the Society of Construction Law Delay and Disruption Protocol (SCL 2nd Protocol)[3]. In this article, I summarise the factors to consider when selecting and implementing delay analysis methods.

In 2012, I carried out research in an attempt to identify the key factors influencing both the selection and implementation of delay analysis methods and to create a road map for selecting the most appropriate technique. I formulated my research into my master’s dissertation and it was later published in the International Journal of Construction Management[4]. I created a road map (The “Road Map”; see figure below) in the form of a series of questions to be asked before selecting the delay analysis method and its level of detail. The model permits multiple iterations until the desired outcome is reached.


In essence, the Road Map places emphasis on the circumstances (i.e. the factors) before selecting the method e.g. project records available, contract requirements, experience of analyst, time to perform the analysis, etc. As the selection narrows, the Road Map on occasions requires that the user revisits earlier questions before deciding on the most appropriate delay analysis method; e.g. where a method is selected but the analyst does not have sufficient time to perform the delay analysis using that particular method.

I have summarised the key factors into 11 groups as follows. I should note that this list is not exhaustive, and they are not in any particular order.

Factor 1: Contractual Requirements

Before selecting the delay analysis method, it is important to have a full understanding of the contract documents in terms of scope, programming, and time management. This includes, for example, standard clauses dealing with the following matters:

  • Commencement and completion,
  • Milestones and partial/ sectional completion,
  • Programming and progress reporting,
  • Variations,
  • Extension of time,
  • Liquidated damages,
  • Delay and disruption costs, and
  • Claims.

While it is unusual for the contract to specify the delay analysis method, it would normally prescribe the manner in which delays are to be managed and administered. For example, the contract may state that a notice should be issued if a delay event will probably cause delay. In this scenario, you may infer that the contract permits prospective and forward-looking delay analysis methods. In some instances, the contract may go further and explain that, for example, you should consider the status of the project just before the commencement of the delay event in analysing the delay impact. In this instance, you may infer that the contract requires a periodic analysis method such as the Time Impact Analysis or the Time Slice Windows Analysis (which I’ll describe in my next article).

However, even if the contract includes express provisions in terms of delay analysis, you cannot blindly accept it without applying professional judgment and common sense. For example, it may be inappropriate to perform a prospective delay analysis method (e.g. produce a hypothetical estimate of the delay) when the delay event and/ or the project is completed and the actual delay periods are known.

The key message here is that you should consider the contract and explain how it affected your selection and implementation of the delay analysis method.

Factor 2: Time of Performing the Analysis

According to AACE RP-29R-03, if you are performing the delay analysis before commencement or during the delay event (i.e. contemporaneously), then you are performing “prospective” delay analysis[5]. If you are performing the delay analysis after the completion of the project and/or event, then you are performing “retrospective” delay analysis. In other words, prospective and retrospective categorisation reflects the actual physical point in time that the analyst performs the analysis.

The SCL 2nd Protocol categorisation slightly differs in that it refers to the reference point in time rather than the actual physical point in time when the analysis is performed. For example, the SCL 2nd Protocol refers to prospective delay analysis as forward-looking methods (i.e. estimating future delay impacts) and retrospective delay analysis as backward-looking methods (i.e. analysing actual delay periods). In this series of articles, I use the SCL 2nd Protocol’s terminology.

Notwithstanding, consideration of the actual physical point of time when the analysis is to be performed is vital to the successful selection and implementation of the delay analysis method. As a general rule, the delay analysis should answer the questions of “What is the estimated delay?” when analysing the delays contemporaneously (before knowing the actual impact of the delay events) and “What is the actual delay?” when analysing the delays after the event.

It is generally inappropriate to perform a prospective delay analysis when analysing delays after completion of the event. However, in certain circumstances, the analyst may have to do so when it is important to compare the potential impact of a delay compared with its actual impact. This may be necessary when considering disputes pertaining to acceleration, mitigation and pacing.

Factor 3: Purpose of Analysis

The delay analyst should understand the scope of the analysis, the desired outcome and the target audience.

For example, if the scope requires identification of slow progress delays and acceleration periods, the analyst may have to eliminate some methods (e.g. Impacted As Planned) or consider certain variations to the standard methods to ensure the analysis produces the desired outcome.

The target audience will influence the level of detail included in the analysis. For example, an analysis performed at a project site may not require a sophisticated level of substantiation given the parties involved are generally aware of the project issues and the dispute had not yet crystalised.

However, if the same analysis is carried out as part of a litigation or arbitration procedure, the analyst would be expected to provide fully detailed substantiation, including narratives and backup documentation, satisfying the standard rules of evidence[6].

Factor 4: Source Data Availability and Reliability

The analysis will only be as good as the records it relies upon. It is important that the analyst is aware of what records are available and, also, how reliable and complete the records are. For example, most of the delay analysis methods require a baseline program to compare with actual progress and/or delay. Some of the methods require the baseline program to be a logic-based schedule[7] in order that the delay and its impact can be modelled.

If the baseline program, for example, is not realistic or does not reflect the full scope of work, it is likely that it would be inadequate/inappropriate to use in any form of delay analysis. Consequently, the analyst is faced with the decision on whether to use a method that does not rely on a baseline program or, alternatively, the analyst creates, improves or corrects the baseline program. Every decision made in the process, raises further questions and issues and the analyst is required to explain and demonstrate that these had been carefully considered and dealt with in their report. Anything short of this and the analyst would likely face criticism.

The other important set of data to consider are the available contemporaneous records. These include progress reports, updated schedules, correspondence, photographic evidence, witness statements, inspection and handover reports, and others; all of which record what happened at the material time(s) that the works were progressing. Without such records, the analysis would not be able to accurately take the actual progress into account and determine the as built critical path, where applicable.

Factor 5: Complexity and Size of the Dispute

The more complex and larger the dispute, the more sophisticated the delay analysis is likely to be. Early understanding of the details of the dispute will enable the delay analyst to decide on both the method to use and the level of detail required. It should be noted that overly complicated matters may require the analyst to simplify them rather than further compounding the complexity of the matter with detailed and intricate delay analysis.

An element of professional judgment on a case-by-case basis is required. For example, if a dispute involves 500 delay events over a short period of time, the analyst may consider combining some of the events as one wrapped-up grouped event (e.g. late issuance of 100 individual design drawings). Similarly, if there are very few events over a long period of time, the analyst may need to further break them down to a reasonable level (e.g. lack of access to individual areas).

Factor 6: Budget and Time Allowed for the analysis

If I had all the time I wanted, I would review every single piece of information on the project and implement multiple delay analysis methods with simulations under different scenarios considering the facts and assumptions of the case. In practise, this is not necessary and cannot be justified.

The time (and hence cost) spent on the analysis should be proportionate to and commensurate with the dispute size and issues in question. In some instances (e.g. adjudication cases), there will be strict time limits to complete the analysis. Some clients may have a limited budget that they cannot exceed.  The key message here is that the analyst will need to decide if he can select and implement a certain delay analysis method within the time and cost constraints.

In any event, in the delay report, the analyst should explain both what could be done, and could not done, because of such constraints. For example, the analyst may state that the actual dates in the as built program could not be verified because of the time limitation for producing the report and therefore the analysis assumed the reported as built dates were accurate.

Factor 7: Expertise and Skills of the Delay Analyst

Delay analysis is associated with the planning and scheduling disciplines and normally relies on the same set of scheduling tools. However, delay analysis requires a unique mindset and skillset. Usually, the project planner is best placed to explain the delays and the impacted time paths on the project. However, the planner may not have adequate experience to select and perform the analysis. It is important to note that having the necessary academic knowledge on the delay analysis does not necessarily qualify the analyst to perform the analysis as, in practise, experience is required to be able to make reasonable professional judgements on the matters in question.

Another aspect to consider is that, in addition to the necessary technical skills, the analyst may require strong presentational (both written and oral) and report writing skills. In some instances, for example under cross-examination, the analyst’s ability to answer questions clearly and succinctly under pressure may play a vital role in demonstrating and justifying the results of the analysis.

It is important that the analyst selects a method that is within his/her area of expertise and can disclose his/her experience in performing such methods to the relevant stakeholders. In some instances, it may be appropriate that a third party with experience and reputation in the market becomes involved.

Factor 8: History and Usage of Methods on the Project

If a delay analyst is introduced to a project at a late stage in the project and after delay analysis (in some form) had been conducted by either party, it is important that the analyst is made fully aware of all pertinent history relating to the evolution and content of the analysis. In particular, it is essential that the delay analyst is aware of what delay analysis methods had been previously conducted and any aspects that had been agreed or disagreed between the parties in this respect.

For example, if a Time Impact Analysis method had previously been performed and disagreed between the parties, the analyst would need to understand the specific circumstances that had led to this disagreement.  This is necessary in order that the delay analyst is able to make an informed decision as to the selection and implementation of the method to apply i.e. either a new method or the same method as previously performed.  It may not necessarily be the method that was in dispute between the parties but the manner in which the previous analysis had been performed, the records relied upon etc.  Even if the analyst decides to use a new method, there may be certain aspects of the previous delay analysis that can be used.

Factor 9: Delay Events

The nature and number of delay events in question affects the decision-making process in terms of the selection and the level of detail of the analysis. Delay events are typically categorised as employer, contractor and neutral events. Reference to the contract is necessary to identify the risk allocation between the parties, e.g. contractor excusable events, contractor culpable events, contractor compensable events, and which events allow the employer to levy liquidated damages.

While it is not for the delay analyst to decide on entitlement, it is important that the analyst has a good understanding of the types of events to be investigated. I note that the “effect-cause” based delay analysis methods[8] investigate the effect (i.e. the delay) before considering the delay events in question and, therefore, such methods would be less reliant on the types of the delay events.

The number of delay events and their distribution over time would influence the selection of the method and the way it is implemented. For example, in a project of a three-year duration, if the delay forecast and the delay events started in the third year only, the analyst may ignore the first two years or consider them as one initial window, and then breakdown the last year in windows depending on the distribution of the delay events; i.e. the nature and distribution of the delay events may influence the selection of the method (e.g. window type delay analysis method) and the implementation of the method (e.g. the periods of the windows).

Factor 10: Capabilities of Methods

There is no one perfect method, and each method carries with it certain strengths and weaknesses. The analyst should therefore be fully aware of the advantages and disadvantages of each delay analysis method. Without such knowledge, the analyst cannot make careful consideration and the selection of the most appropriate delay analysis method, level of detail of the method, implementation of the method, justification of the results and deal with the chosen methodology’s shortcomings.

Factor 11: Other Matters

Unfortunately, it is not possible to create an exhaustive list of all the factors to consider when selecting and implementing the delay analysis method. This is mainly because each project is unique by nature. Therefore, the delay analyst should apply analytical skills and professional judgment on how to analyse the delays based the project specific matters.

Other matters to consider may include:

  • Changed sequence of work,
  • Concurrent delays and pacing,
  • Critical path definition,
  • Ownership of the float,
  • Mitigation and acceleration claims,
  • Disruption in terms of delay effect,
  • Software used, and
  • Scheduling settings (e.g. retained logic or progress override).


In my opinion, the analysis of the above factors is equally important (if not more important) than carrying out the delay analysis itself. It is also important that the analysis and conclusions on the factors are included as part of the delay analysis package, which may include programs, narratives, spreadsheets, and other substantiations (“Delay Report”). I’ll share my recommended structure for the Delay Report in one of my future articles.

In my next article, I’ll share my experience on the common delay analysis methods in the industry considering the above factors, highlighting AACE RP-29R-03 and the SCL 2nd Protocol methods and stressing the key advantages and shortcomings of each method.


Disclaimer: This article is intended to provide an update on the current industry practice in terms of delay analysis.  However, it does not in any way constitute any type of legal or professional advice. 

[1] Delay Article 1:

[2] AACE® International Recommended Practice No. 29R-03 – Forensic Schedule Analysis (25 April 2011 Revision)

[3] The Society of Construction Law Delay and Disruption Protocol, 2nd edition, February 2017

[4] Volume 19, 2019 – Issue 4; Pages 329-340 | Published online: 17 Feb 2018)/

[5] AACE RP-29R-03, Page 12 of 134, A. Layer 1: Timing

[6] For example, the analyst may rely on actual dates reported in programs. In a formal dispute, the analyst may have to further investigate such dates and provide contemporaneous evidence of the actual dates such as site inspection documents, handover records and photos.

[7] e.g. produced with defined sequence of work using one of the available tools such as Primavera P6 or MS Project

[8] Effect-cause based methods focuses on finding the critical path and delay periods, and then investigating the link with any claimed delay events.

2021-09-02T01:56:16+00:00 September 2nd, 2021|Insights, News|0 Comments