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Junk science: the fallacy of retrospective time impact analysis

Thursday 25 July 2024


Credit: See Less/Adobe Stock

Mark C Sanders
QDR International, Wilmington, Delaware
msanders@qdrclaims.com

Mathematical models are commonly used to predict the future. We have models to forecast the weather, models to predict price changes, and models to estimate risks and opportunities. We use these models to support our decision-making when planning events, trading stocks or making sports substitutions.

We use models to help us predict what will happen in the future, but we do not use models to predict the past, only to help us understand it. We do not look to a mathematical model to tell us yesterday’s temperature, last week’s stock prices, or whether our favourite team won or lost. We do not need to predict what happened yesterday. For that, we look to the record of actual events. If our model does not align with actual events, then the model is imperfect, at best.

Somehow, we have lost sight of this common sense understanding when analysing delays to complex construction contracts. Retrospective time impact analysis (TIA), one of the most popular techniques of forensic delay analysis, relies on building mathematical models of the past. Discrepancies between those models and actual events are commonly explained away or ignored. For both theoretical and practical reasons, the approach is wrongheaded, and courts have started to recognise it as junk science. Meanwhile, general confusion among the techniques available for delay analysis still makes it difficult to separate outdated retrospective TIA from more scientific approaches.

Introduction

Best practices in both science and law counsel us to observe the past and model the future. In Francis Bacon’s inductive approach to the scientific method, observation precedes prediction, which helps to eliminate bias.[1] By contrast, Karl Popper found that most science begins with inspiration rather than observation, but through a deductive approach, the good scientist focuses on trying to falsify a theory rather than verify it.[2] Both approaches recognise the need to eliminate the bias inherent in our assumptions and to focus on the observable facts. Like the scientific method, rules of evidence are designed to help us to ascertain the truth.[3] Consistent with that intent, expert analysis and testimony should help triers of fact to determine what happened and avoid obscuring what happened by adopting flawed models.

Modern retrospective TIA techniques rarely align with good scientific and evidentiary principles. To understand why that is, it is helpful to recall that there was never any scientific theory behind TIA when it was first developed.[4] Jon Wickwire, who first introduced the legal community to the elements of the TIA technique in 1974, bluntly called it an ‘exercise in salesmanship’.[5] So, what is being sold to triers of fact? And how many of them are still buying it?

AACE International notes that ‘time impact analysis (TIA) has a bewildering array of regional variations’.[6] The term is maddeningly vague, to the point that the United States Patent and Trademark Office concluded that ‘time impact analysis’ and ‘TIA’ are no more than generic terms for any schedule analysis services for construction projects.[7] An expert that describes an analysis as a TIA without further definition is akin to a doctor saying that a patient has received heart surgery without clarifying whether the surgery involved an arthroscopic stent, a bypass operation or a full transplant.

Still, notwithstanding fringe uses of the term, modern TIA techniques have come to include a few key elements. These include the creation of one or more fragnets to model delay events and inserting those fragnets into a contemporaneous project schedule, normally the project schedule published most recently before each event occurred.[8] The delay analyst validates the project schedules, reviews actual events, creates fragnets to model the delays, inserts the fragnets into the contemporaneous schedules and observes the resultant impact on one or more contract milestones. That is the essence of the approach accepted in many tribunals. However, triers of fact have begun to recognise that the retrospective application of the TIA technique is unscientific and flawed.

The rise and fall of retrospective TIA

The TIA technique was developed in the US and was well-established by the 1980s.The application of the technique accelerated globally after its endorsement in the first version of the Society of Construction Law (SCL) Delay and Disruption Protocol in 2002.[9] More recently, some surveys have noted a collapse in the use of TIA, which observational analysis techniques have replaced.[10] Recent polls of practitioners by AACE International have shown a trend towards observational methods rather than after-the-fact modelling,[11] and US court cases show a decline in the use of modelled approaches to delay analysis in the past decade.[12]

Modern retrospective TIA techniques rarely align with good scientific and evidentiary principles

One reason for the trend away from TIA is the increase in computing power available since the 1980s. Modern computers allow observational techniques that recalculate the entire schedule network for every day of the project based on progress reported each day.[13] While TIA may require a significant effort by the analyst to create the fragnets for insertion, the computing power required to process the analysis is effectively no more than to calculate contemporaneous critical path method (CPM) schedules.[14] The ability to quickly recalculate the schedule based on the interim status of activities every day makes detailed observational techniques more practical and accessible than they were at the time TIA arose.

The recognition of the technical limitations of TIA provides another reason for the decline in its use. SCL notes that TIA ‘does not capture the eventual actual delay caused by the delay events as subsequent project progress is not considered’.[15] SCL contrasts the TIA approach with the two approaches it describes as windows analysis—time slice analysis, in which the analyst must determine ‘the extent of actual critical delay during each window’ and ‘reflect the actual progress of the works’ and as-planned v as-built windows, in which the analyst ‘determines the contemporaneous or actual critical path in each window by a common-sense and practical analysis of available facts’.[16] Unlike prospective analysis, retrospective analysis should align with the facts of what occurred, as described in the windows techniques. Like a model of yesterday’s weather, the TIA approach has little value for understanding the past if it does not align with the details of what happened.

In Costain Ltd v Charles Haswell & Partners Ltd (2009), the court provided specific and general criticisms of the TIAs submitted.[17] In Costain, each of the delay experts was criticised for choosing to analyse the delay events that were beneficial to their respective clients. The analysts controlled what to include or exclude in their analyses. As noted by Vernon, those critical decisions in TIA are ‘often part of the appendices to expert reports and masked to seem like facts’.[18]

In characterising TIA as a ‘cause & effect’ approach, SCL highlights the unscientific nature of its application to retrospective analysis. In such an analysis, the ultimate effects of all events, taken as a whole, are already known. That evidence must be reviewed in detail and analysed to identify and isolate the causes of the net effect. In other words, the analyst already knows when a milestone was completed, and the delay to the milestone is the ultimate effect. That is an input to the analysis. The analyst must work to determine the causes of the delay, which are the outputs of the analysis. SCL calls this an ‘effect & cause’ approach, which aligns more closely with the principles of the scientific method.

By contrast, the TIA approach involves proposing causes and modelling effects. Once that is done, discrepancies between the model and reality are either resolved or simply ignored. To the extent they are resolved, the resolution is not in disproving the original assumptions (compare to Popper) but in the interest of reinforcing those assumptions by explaining any discrepancies between the model and the reality of what occurred. The counterparty is left to attempt to falsify the model. That approach may comport with an adversarial legal process, but it does not comport with good science.

Technical reliability should be the foundation for the selection of a particular method of analysis

US federal courts may bar expert testimony that is not based on ‘reliable principles and methods’.[19] However, few complex construction cases are tried before a jury, and judges have less reason to fear that an expert witness may unduly persuade them. Thus, in complex construction cases tried at the bench, testimony based on methods of questionable reliability is more likely to be admitted than excluded. The court will weigh the reliability of the technique and the credibility of the expert, and any case may turn on the facts more than the delay analysis methodology selected. Likewise, arbitrators are more likely to admit expert testimony and judge for themselves whether or not it is persuasive.

Even in the case of a jury trial in the US, ‘the trial court enjoys vast discretion in deciding whether to admit expert testimony under Rules 702 and 403’.[20] Judges do not appear likely to bar delay analysis methods. In Second World War Theatre, Inc v Desimone Consulting Engineering Group, LLC (2021), a party sought to exclude expert testimony regarding schedule delay analysis because the testimony failed to use a CPM of analysis, ignored projected completion dates, and failed to assess delays separately and in chronological order.[21] The court admitted the testimony, noting that determining which delay analysis methodology was convincing would be the jury’s province. The court further stated that industry sources describing the ‘legal acceptance’ of methodologies were based on whether the analyses had been given greater weight by the factfinder in a particular case. Those reviews would not determine whether a particular method was admissible.

Similarly, concerning the SCL Protocol, the court in Adyard Abu Dhabi v SD Marine Services (2011) found that testimony on delay analysis is not necessarily guided nor constrained by whether a particular technique appears in the protocol.[22] In Alstom Limited v Yokogawa Australia Pty Ltd (2012), the court acknowledged the techniques listed in the protocol, concurred with both testifying experts in agreeing that the ‘as-planned impacted’ and ‘as-built collapsed’ techniques would not be appropriate for the case, and accepted the experts’ analyses termed ‘as-planned v as-built analysis’ and ‘time impacted/windows analysis’.[23] The court followed the experts instead of guiding them on what technique to use.

Notably, these cases mark both a continued casualness in the naming of the delay analysis techniques cited in court opinions and the courts’ willingness to admit a variety of methods. Thankfully, there is no trend of facial rejection of techniques based on casually applied names. Instead, courts have looked to the facts and the credibility of the experts in each case. That is a reasonable approach for the courts to take.

Court acceptance alone has never been a valid basis for the reliability of technical analysis. Instead, the supposed experts must themselves examine the reliability of their techniques. This is the better approach. Science and technical practice should be characterised first by relevant technical considerations, not acceptance by non-practitioners, even though they may be judges. Courts will assess the relevance of expert testimony, its reliability and its helpfulness against the potential for time wasting, confusion and prejudice.[24]

The inherent conceptual flaw of retrospective TIA

Expert practitioners must assess the reliability of TIA techniques with a cold eye. The reliability of a technique can be characterised by achieving similar results based on similar inputs. The TIA technique requires modelling delay events with fragnets created by the analyst. How likely is it that ten analysts, independently reviewing the same complex project, would model events similarly? If ten or 100 activities were in progress at the time of a delay event, would the analysts model the same impacts, the same relationships and the same durations? Would they report the same causes of delay? Given the number of variables involved, it is unlikely that they would. In a complex case, they could not reliably report the same result, given the same project documents as inputs.

The fragnet models used in the TIA approach are developed only after the analyst has reviewed other evidence to identify the delays to be modelled. During modelling, the analyst determines how the activities are related. These determinations are inputs to the analysis, not outputs from it. Not every day is analysed, not every delay is modelled and many critical variances are unexplained. This is a flawed and unscientific approach. It always has been.

Expert judgement in the creation of input assumptions is reduced and moved towards interpreting the analysis results

The critical path is the longest path of activities through the project schedule.[25] In evaluating delays to any project milestone, the analyst analyses the activities on the critical path and asks whether they progressed as planned. The analyst can do this for each day of the project. Determine the critical path, assess progress, calculate any impact on the completion date, assess any changes to the path and proceed to the next day. The net cumulative impact of all calculations will explain the net change to the project completion date from the original plan to the final as-built schedule. Based on these objective calculations, causes and responsibilities for critical delays can then be determined. This is a consistent and objective approach to schedule delay analysis, supported by the scientific method.

This approach is consistent with the ‘effect & cause’ category of SCL’s Protocol and the observational approaches of AACE International. The inputs to the analysis come from the contemporaneous project schedules and as-built data. The outputs are objective and reproducible. Given the same input data and analytical process, ten analysts can produce the same results. This is not true of the TIA process, which requires the analyst to make hundreds or even thousands of decisions concerning what events to model, how to model them and how to tie those models to the contemporaneous project schedules. In short, observational approaches are more reliable from a scientific standpoint. Expert judgement in the creation of input assumptions is reduced and moved towards interpreting the analysis results. This fact-based and common-sense approach compares the contemporaneous plan to what occurred on the project, not some after-the-fact model.

Prospective TIAs

TIA remains useful in evaluating the impact of changes to project scope and assessing impacts to the contemporaneous schedule. Many contracts still specify prospective TIA, particularly for time extension requests associated with added scope.[26], [27] However, the use of prospective TIA in contracts does not imply that its retrospective application is valid, and some contracts now specifically exclude TIA for retrospective application and require an observational approach.[28]

Lawyers and analysts should not mistake prospective TIA in contracts as a recommendation for its retrospective use. Prospective TIAs can be useful in negotiating change orders and time extension requests. Still, once a project is completed and all impacts are in the past, better analysis approaches are available. Unresolved change orders may become claims, but once that happens, contemporaneous schedules and prospective TIAs should be analysed in comparison to actual events using an observational approach, ideally, contemporaneous period analysis.

Lawyers and analysts should not mistake prospective TIA in contracts as a recommendation for its retrospective use

Conclusion

We do not need a meteorologist to predict yesterday’s weather or a financial analyst to predict last week’s stock prices. We do not ask bookmakers to recalculate odds for games that are finished. Why do we build new schedule models of past delays, creating variances between the after-the-fact model and the as-built data?

Retrospective TIA techniques that spread during the 1980s lack a valid theoretical foundation and do not align with the scientific method. The techniques require extensive expert judgement to model analysis inputs and then focus on aligning those models to reality rather than falsifying the original assumptions. Analysis techniques should use the best available evidence, not after-the-fact models. Expert judgement should be applied after applying reliable analysis techniques, not to create inputs for those techniques.

AACE and SCL have made strides in clarifying and differentiating observational from modelled techniques, but there is more work to be done in this area. The industry should continue to work to highlight the principal elements of each technique so that one can be differentiated from another. The differentiation of techniques based on their principal characteristics will help the industry and courts to separate reliable approaches from junk science.

 

[1] Francis Bacon, Novum Organum (John Bill 1620). For further discussion of application of Bacon’s approach to the scientific method to construction schedule delay analysis, see Mark Sanders, The Theory of Delay, 2020 AACE International Transactions, CDR-3415.

[2] Karl Popper, The Logic of Scientific Discovery [Logik der Forschung] (Julius Springer, Hutchinson & Co 1934). Popper was critical of Bacon’s ‘myth of a scientific method that starts from observation and experiment and then proceeds to theories’,
p 279, however, Popper’s emphasis on falsification of theories as opposed to validation was consistent with that aspect of Bacon’s approach. Bacon said, ‘[I]t is the peculiar and perpetual error of the human understanding to be more moved and excited by affirmatives than negatives, whereas it ought duly and regularly to be impartial; nay, in establishing any true axiom the negative instance is the most powerful’. (Bacon, 1620) p 13.

[3] Fed R Evid 102 (US), eg, ‘Purpose. These rules should be construed so as to administer every proceeding fairly, eliminate unjustifiable expense and delay, and promote the development of evidence law, to the end of ascertaining the truth and securing a just determination’.

[4] Mark Sanders, ‘Time Impact Analysis: Past, Present, and Future’ (2024) AACE International Transactions, CDR-4398.

[5] Jon Wickwire and Richard Smith, ‘The Use of Critical Path Method Techniques in Contract Claims’ (1974) 71 Pub Cont LJ 1.

[6] AACE International, Recommended Practice No 29R-03, Forensic Schedule Analysis, Morgantown, WV, AACE International, 2011, s 1.4.

[7] Capital Project Management, Inc v IMDISI, Inc, No 91121819 (US TTAB, 2003), ‘The term “Time Impact Analysis” clearly is generic for the category of services listed in applicant’s recitation […] relevant public, including sophisticated attorneys, contractors and engineers in the construction field, would perceive the term as generic’.

[8] AACE International, Recommended Practice No 29R-03, Forensic Schedule Analysis, Morgantown, WV, AACE International, 2011, s 3.7.E.

[9] The Society of Construction Law, Delay and Disruption Protocol (2002). The original 2002 protocol stated that TIA was the preferred technique for retrospective analysis when appropriate information was available, but a 2015 rider and 2017 revision of the document abandoned the preference for TIA.

[10] François Michaud, A Statistical Review of Delay Analysis Techniques Used Over the Last Decade www.hka.com/a-statistical-review-of-delay-analysis-techniques-used-over-the-last-decade/#_ftnref6 accessed 3 April 2024. Analysed cases from 2010 to 2021, where more than $5m was at issue and the delay analysis technique was not specifically prescribed by contract: in the Americas (32 per cent), Europe (28 per cent), Asia (14 per cent), Middle East (14 per cent), Oceania (ten per cent), and Africa (two per cent). The review found that the use of observational techniques far exceeded the use of modelled techniques, including TIA: as-planned v as-built (52 per cent), criticism of claimant’s analysis without separate analysis presented (13 per cent), time slice analysis (12 per cent), TIA (seven per cent), retrospective longest path (five per cent), impacted as-planned (five per cent), collapsed as-built (three per cent) and other methods (two per cent). Based on the SCL categorisation, TIA, collapsed as-built and impacted as-planned are categorised as ‘cause & effect‘ methods (AACE calls these ‘modelled methods’). As-planned v as-built, time slice analysis and retrospective longest path are categorised as ‘effect & cause’ methods (AACE calls these ‘observational methods’). Summarising, the effect & cause (observational) methods were used 69 per cent of the time; and the cause & effect (modelled) methods were used 15 per cent of the time. Criticism without an affirmative method was submitted 13 per cent of the time, a method not explicitly definable within SCL’s classification was submitted two per cent of the time and one per cent is left as a rounding error.

[11] Two polls of delay analysis practitioners conducted by AACE International in 2023 suggest a downward trend in TIA. First, in a survey of 498 webinar attendees in July 2023, AACE International found 77 per cent of attendees were using observational methods (30 per cent as-planned v as-built and 47 per cent contemporaneous period analysis ) and 23 per cent were using modelled methods (20 per cent TIA and three per cent collapsed as-built). Another survey of 545 attendees at a presentation on TIA in September 2023 found that only 55 per cent of attendees were using TIA retrospectively, as opposed to prospectively.

[12] W Stephen Dale and Robert D’Onofrio (eds), Construction Schedule Delays (Thomson Reuters, 2023). Figure 12-6 provides a table of 184 US cases from 1968 to 2023. The table finds observational techniques applied about twice as often as modelled techniques from 2013 to 2023. While the techniques tabulated are noted as ‘accepted’ or ‘not accepted’, they were all admitted as evidence, and questions on expert testimony regarding each application would properly apply to the ‘credibility of the testimony, not the admissibility’, Hose v Chicago Northwestern Transp Co, 70 F3d 968, 974 (8th Cir, 1995). In summary, all of the techniques were accepted as evidence, but individual applications were found more compelling than others in some cases. Comparing the results of this review to either the AACE or SCL categories of delay analysis is challenged by the unique categories used in Dale and D’Onofrio’s approach, which combines windows analysis as a subset of TIA, calling it the ‘Unadjusted TIA (Windows) Method’ and noting ‘The Windows method is a type of TIA that uses “windows” to look at the slices of time’. By contrast, both AACE and SCL separate windows methods from TIA. AACE notes that the term is used for observational methods, which align with SCL’s ‘effect & cause’ methods, whereas TIA is a ‘cause & effect’ method. See also Richard D’Onofrio, 33 WTR Construction Law 6, acknowledging that ‘a lack of standardised terminology has led to confusion’. Still, the recommended method of analysis in Table 12-6, ‘adjusted TIA’, appears in only five of the 34 cases reviewed since 2013. In those five cases, it is described as ‘accepted’ four times and ‘not accepted’ once, but in three of the four ‘accepted’ cases, the opposing party presented no rebuttal analysis. In the fourth, the analysis utilised schedules from a request for equitable adjustment prepared during the project using a prospective, not retrospective, TIA method. The opinions in these cases spent far more time on the project-specific facts and made no determination as to the acceptability of any schedule delay analysis technique. No firm conclusions as to the validity of any technique should be drawn from cases in which that technique was presented without opposition and the actual analysis is not available for review. This contrasts with the assertion that ‘looking at acceptance rates in totality can paint a persuasive picture’, as noted in the text that introduces Figure 12-6. A better takeaway from this review is that ‘the scheduling experts largely talk past one another. Each expert says his approach to quantifying delay is correct and the other expert’s approach is wrong’, CTA I, LLC v Dep’t of Veterans Affairs CBCA5826 et al 22-1 BCA (CCH) 38083, 2022 WL884710 (Civilian BCA, 2022)

[13] Contemporaneous period analysis or as-planned v as-built techniques using the daily delay measure (DDM) technique may recalculate the entire CPM network daily or even hourly. See AACE Recommended Practice No 29R-03, s 3.1.F.1. The technique has been applied on a static/global basis or a dynamic/periodic basis, tracking the progress of every activity in the schedule network for every day of the project. Commercially available software can now support application of these techniques. With respect to as-planned v as-built methods, there are significant differences between a DDM implementation and a ‘total time’ implementation. As with any method, the details of the implementation must be understood to determine whether the method has a valid scientific basis. Among these details, it is important to understand how criticality is determined and whether that determination is made objectively or subjectively.

[14] Each iteration of TIA requires a standard CPM calculation done on one data date, whereas DDM techniques may be performed by updating and recalculating the entire schedule for every day of the update period to dynamically identify and measure delays, recoveries and changes to the critical path.

[15] See n 9 above, p 36.

[16] Ibid.

[17] Costain Ltd v Charles Haswell & Partners Ltd [2009] EWHC 3140 (TCC). In addition to criticising the analysts for making limited investigations of the facts for some of the delays reviewed, the court makes several statements in its opinion that give pause with respect to the schedule analyses presented and their understanding. The court equates ‘time impact analysis’ with ‘windows slice analysis’, stating that both function by ‘impacting the effect of that delaying event on the Contract Programme in order to establish the time effect of that event’ (para 176). SCL later differentiated these as two separate techniques. The court also indicates that some of the analysis was made applying ‘progress override’ calculations, which may well have had a significant impact on the result of any analysis (para 177). The court indicates a preference for time impact analysis over time slice windows analysis (‘windows slice analysis’), despite having equated the two (para 179). The court then states, ‘It is not clear to me what difference to the actual results these alternative approaches lead to […]’ (para 179). Finally, the court states that the TIA model prepared for litigation ‘eliminates any subjective distortion or manipulation’ in the contemporaneous project schedules (para 180). In fact, a TIA must begin with a contemporaneous project schedule and does not necessarily align with actual project events, as noted by SCL. Considering that TIAs are normally prepared by parties seeking time extensions and any associated costs, they are not likely to be less biased than the underlying schedules from which they begin. TIAs normally show more delay than contemporaneous project updates, although perhaps that was not the case in Costain. In the end, the case highlights continued confusion over the basic elements of a TIA. It appears that the experts may have agreed to use either a TIA or a time slice windows analysis, which was interpreted as meaning that they had both agreed to perform a TIA.

[18] L Vernon, ‘Which methods of delay analysis have been used in disputes based on English and Commonwealth case law during the last 25 years? Does a practical approach to delay analysis selection . . .’, Robert Gordon University Aberdeen, LLM/MSc Dissertation, Construction Law (2023).

[19] Fed R Evid 702 (US).

[20] United States v Montas, 41 F3d 775, 784 (1st Cir, 1994).

[21] Second World War Theatre, Inc v Desimone Consulting Engineering Group, LLC, et al, No CV 19-11187, 2021 WL 1313408 (ED La, 2021).

[22] Adyard Abu Dhabi v SD Marine Services [2011] EWHC 848 (Comm) (High Court Of Justice, QB Division, Commercial Court).

[23] Alstom Limited v Yokogawa Australia Pty Ltd (No 7) [2012] SASC 49 (Supreme Court Of South Australia). The court here does not use the same names that the SCL Protocol uses for the four techniques it lists. In the case of the first two analyses, the court merely transposes words. More interestingly, the word ‘windows’ used by the court (and apparently, the experts) to refer to the third technique appeared nowhere in the 2002 SCL Protocol (the case was tried in 2012), and the word is used for two methods that are explicitly differentiated from TIA in the 2017 version of the protocol. Thus, the court here adopted the industry’s general conflation of the terms TIA and windows, without regard for the particular language of the protocol. For a history of the conflation and differentiation of the terms TIA and windows, as the terms came into use during the 1980s and 1990s, see n 4 above.

[24] Calvin Sharpe, Reliability Under Rule 702: A Specialized Application of 403, 34 Seton Hall L Rev 289.

[25] AACE Recommended Practice 10S-90, Cost Engineering Terminology, 2024.

[26] Federal Acquisition Regulation (US), eg, ‘FAR 52.211-13, Time Extensions, is supplemented as follows: […] the Contractor shall base its request on an analysis of time impact using the project schedule as its baseline’.

[27] NAVFAC Specification (US), Unified Facilities Guide Specifications, eg, Section 01 32 17.05 20, Network Analysis Schedules (NAS) For Design-Build, 11/07, 1.7 Contract Modification, ‘Submit a Time Impact Analysis with each cost and time proposal for a proposed change. Time Impact Analysis (TIA) shall illustrate the influence of each change or delay on the Contract Completion Date or milestones. Each TIA shall include a Fragmentary Network (fragnet) demonstrating how the Contractor proposes to incorporate the impact into the contract schedule.’

[28] Department of Veterans Affairs Specifications (US), eg, s 01 32 16.13, Network Analysis Schedules – Major Construction Project, Design-Bid-Build (TIA appropriate for prospective analysis of added scope but not for retrospective delay analysis): ‘Retroactive TIA long after (generally over 3 months) the initiation of impact with “as-built” logic / duration will not be accepted as a normal practice. The contractor is required to perform TIA […] within a month of VA issued Change or other directives to proceed with additional work.’ Contrast with: ‘All delays due to non-work activities/events such as RFIs, STRIKES, and similar non-work activities/events shall be analysed on a month by month basis and must be supported with a justification, CPM data and supporting evidence as the Contracting Officer may deem necessary for determination as to whether the Contractor is entitled to an extension of time’.

Mark C Sanders is a partner at the Wilmington office of QDR International. Mr Sanders has over 25 years of experience in engineering, construction and dispute resolution. He is a licensed professional engineer in Delaware, Maryland, Pennsylvania and Wisconsin, and a member of the California Bar. He holds certifications from AACE International as a Cost Professional, Planning and Scheduling Professional, and Forensic Claims Consultant. He is a certified Project Management Professional and Portfolio Management Professional. He currently serves as the Secretary of AACE International. He can be contacted at msanders@qdrclaims.com.