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September 06, 2019 Articles

The Future of Forensic Schedule Delay Analysis

Time is an essential element of all construction projects, and construction professionals should all be aware of the principal issues associated with extensions of time and delay claims.

by John C. Livengood

It is safe to assume that contractors have been asserting delay claims or their effective equivalents on projects since before the start of recorded history. While we have no record of delay claims on the Pyramids, I am sure that King Djoser’s architect Imhotep, hoped the funerary pyramid he designed would be completed prior to, or at least near to the time of death of the king in 2670 BCE, even though it took dozens of years to complete. Similarly, we do know that in medieval times the popes who built the Duomo in Florence and St. Peters Basilica in Rome complained to their master-builders Brunelleschi and Michelangelo about the very long time and the cost overruns these projects had on the way to completion. Much more recently, U.S. courts have reported delay claims for more than 100 years.

Since the mid-20th century and the advent of critical path method (CPM) scheduling, that invention has not only revolutionized both the planning and execution of construction projects, but also the claims for delays asserted by contractors. These claims are different than their predecessors only in the potential for “scientific” proof of delay. CPM schedules came into existence in the late 1950s with the development of the UNIVAC computer and the work of J. Mauchly and J. Kelley on behalf of DuPont. Those initial trials of this schedule system proved almost immediately that CPM schedule development could save considerable time. Shortly thereafter, the Navy’s Polaris Program developed a statistical tool called the project evaluation and review technique (PERT). So that by the end of the 1960s, CPM scheduling fundamentals were essentially in place, albeit working on computers we would consider unbearably slow today.

In the mid-1960s some schedule experts started to identify and quantify delays through the use of “time-impact analysis” (TIA) and snapshots of time. As the Apollo moon project advanced, experts working with the CPM schedules used time-impact analysis methods to quantify and project time delays that occurred on the project. As CPM usage became more prevalent, the number of different forensic schedule delay methods seems to have grown rapidly, with some current commentators having identified up to 14 different methods, (R. D’Onofrio and A. Meagher, What is a Schedule Good For? A Study of Issues Posed by Schedules on Complex Projects, ABA Constr. Law., (Winter 2013)) while others aggregate the subtle differences into four major families. (P. Levin, ed., Construction Claims, Changes, and Dispute Resolution, 3rd Ed., Chapter 8 (ASCE Press, 2016))

While delays occur on all projects, constructors and owners work diligently to avoid delays, and if they occur, to recover from them. Most of the time, their efforts are successful and therefore few projects have critical path schedule delays and even fewer have claims that result from requests for additional time. Nevertheless, when such claims do occur, they can be complicated and ironically, time consuming. For this reason, time is an essential element of all construction projects, and construction professionals should all be aware of the principal issues associated with extensions of time and delay claims.

Advancements in CPM technology and analysis has continued since the 1960s. Even in the last decade, advancements in CPM software analytics and conceptual advancements in forensic schedule delay methods have enabled persons needing to perform delay estimates or analysis with more choices and better tools to perform this work. Virtually all large construction projects use techniques to evaluate entitlements to time extensions for changed work yet-to-be performed and occasionally to identify entitlement to time extensions for work already performed. Most sophisticated contracts require time-impact evaluations for disputed time entitlement.

More than 50 years after the invention of CPM and the development of CPM-based forensic delay analysis, this analysis activity has matured and is now associated with two contravening trends: (1) fewer legal decisions on CPM issues; and, (2) more and better understanding of delay methods.

Lack of Critical Path Method Law

Court decisions on construction issues, particularly the arcane issues associated with CPM and delay law, are becoming rare. The increased cost of litigation and the corresponding rise of less expensive alternative dispute resolution options, means that fewer court cases are decided and reported that address fundamental legal questions associated with schedule delays. No legal rulings equals no precedents.

For example: contractors schedules that are “reasonable” form the basis of both a contractors planned work effort and a basis for a subsequent delay analysis. Yet courts have so far been unable to provide much guidance on what constitutes a “reasonable” schedule. This issue is particularly important since construction contracts often require contractors to mitigate both their own delay and that caused by owners. It is a nice question as to how much mitigation is required to correct for a schedule that was reasonable before work commenced, but quickly became unreasonable as actual work proceeded.

Another thorny legal question is who owns the float? While the U.S. legal decisions seem united in their rulings that float belongs to the project (whoever uses it first), unless stipulated otherwise in the contract, many commentators and contractors argue that since the schedule is created by the contractor, (it describes the contractor’s work plan and is essentially the contractor’s “means and methods,”) the contractor should be entitled to build in accordance with its schedule and float should therefore be a contractor resource. (S. Hess, Who Should Own the Float, Journal of the College of American Construction Lawyers (Vol. 4, No. 1, Winter 2010)) Yet many owners unrealistically specify that float is an owner resource. Owners that include such provisions are kidding themselves – such provisions simply invite the contractor to manipulate the CPM schedule to eviscerate the provision.

Another CPM related issue not clearly defined by courts is the role of anti-concurrency clauses. In many ways these clauses, usually inserted by institutional or governmental owners, are relatives of no-damages for delay clauses, which are legal in some states and prohibited in others. Anti-concurrency clauses seem never to have been addressed by a U.S. court, but concurrency itself is major issue, even if a complete muddle. As one recent decision observed: “The exact definition of concurrent delay is not readily apparent from its use in contract law.” (George Sollitt Construction Co. v. U.S., 64 Fed. Cl. 229, n. 8, 241 (2005)). The truth of the statement is underscored by the three separate methods U.S. courts seem to have developed in order to address concurrent delay. ( J. Livengood, Comparison of English and U.S. Law on Concurrent Delay, Construction Lawyer (Vol 35, No. 3, Summer 2015))

The most common method, “apportionment” is highly dependent on a detailed CPM analysis. That should work, but even within the technical arena of forensic schedule delay, there is less than technical unanimity as to what is “concurrent.” A typical argument is that a delay on a near-critical path should be concurrent because CPM schedules are simply too inaccurate to define day-for-day critical paths. The other two approaches to concurrent delay in the U.S. courts are just as poorly developed. No wonder jurists find expert explanation of concurrent delay unhelpful in many situations. (C. Brasco and C. Anzidei. Concurrent Delay and the Critical Path: Views from the Bench, Cost Engineering (AACE International, February 2010))

Another and perhaps even more contentious area of unresolved CPM law concerns the role of the agency construction manager (not at-risk) as regards development and adherence to the CPM. While agency construction managers attempt to write virtually all liability for the schedule out of their contracts, courts seem to be trying to hold them to a standard more akin to CM at-risk. This short list highlights but a few of the many areas that CPM law is not well defined by the courts. It is not likely to get better as fewer construction cases result in written judicial decisions. (A. Ness, Whither Construction Law? How Can Construction Law Continue to Grow and Evolve in the Era of “The Vanishing Trial”? The Construction Lawyer (Vol. 30, No. 3, Summer 2010))

While the important CPM-related court cases decided in the late 20th century do occasionally get updated, the trend for resolving disputes points towards more arbitration and mediation. These forums have no public record of the reasons for a decision, thereby they fail to create precedents that can be the basis to resolve future disputes.

While some cynics in the construction industry may welcome the reduced number of court decisions, the absence of definitive legal explanations hinders management, administration, and resolution techniques for projects. Yet the very trend toward arbitration and expert mediation can empower informed and knowledgeable resolution because of the more expert arbitrator or mediator involved in the more complicated construction projects. One prominent observer has hypothesized that with the reduction in judicial decisions, the professional organizations might take up the slack (not float). (A. Ness, Experts and Expertise in Construction: Black Letter Law and the Debate of Whether Scheduling /Programming Experts Are Imposters—It’s All Smoke and Mirrors (Conference of the International Bar Association, Dublin, 1 Oct. 2012); A. Ness: Delay Analysis - Some Big Unanswered Questions (ABA Construction Forum, October 2016))

Guides to Forensic Delay Analysis

In the decades that followed the invention of time-impact analysis in the mid-1960s, there was an explosion of forensic delay CPM methods. A review of literature developed in the 1970s and into the 1980s reveals dozens of methods with different names. Some were genuinely different, but most were variations on some basic models, and some may have been simply experts trying to stakeout a methodology to call their own. At this same time, expert legal and technical articles started to appear that provided the conceptual framework for forensic schedule delay analysis. (J. Wickwire and R. Smith. The Use of Critical Path Method Techniques in Contract Claims, Public Contract Law Journal, Vol.7, No.1 (1974), p 23.) A re-read of this and other pioneer articles shows the depth of understanding the authors had on the subject. Many of the common methods we know today were identified and discussed, and form the four basic families of forensic delay methods: (1) as-planned vs. as-built; (2) contemporaneous period analysis (aka “windows”); (3) time impact analysis (including impacted as-planned); and (4) collapsed as-built (aka “but-for”).

The near-riot of different names for similar or identical methods were partially organized and given some form by the early editions of works such as Jon Wickwire et al.’s book, Construction Scheduling: Preparation, Liability and Claims, 4th ed. (Wolters Kluwer, 2018), and Barry Bramble et al.’s book, Construction Delay Claims, 3rd ed. (Wolters Kluwer, 2010). The stage was therefore set for the first comprehensive peer-reviewed guide to delay methodology, which was published in 2002 in the United Kingdom. The Society of Construction Law Delay and Disruption Protocol provided a detailed framework for the management of a project and subsequent forensic analysis in the United Kingdom. While widely used in countries that generally follow U.K. law, it had only minimal impact in the United States, and some commentators believed it was inappropriate for the U.S. legal system. (E. Barba., G. Lare and R. Lowe. View from Across the Pond: An American Perspective on the Society of Construction Law’s Delay and Disruption Protocol. The Construction Lawyer, No. 27, Vol. 1, Winter 2007, at 23.) The 2017 revision of this document is a welcome enhancement as it covers more forensic delay methods that the earlier version and makes a myriad of needed changes throughout the document. (

In the United States, which has been the leader in world-wide development of CPM theory and application as well as forensic schedule delay, AACE International first published in 2007 its peer-reviewed guide to forensic schedule delay methods, the Recommended Practice of Forensic Delay RP29R-03 (FSA 29R-03). (

The successful organization of the various FSA methods (there are nine identified in the FSA 29R-03) has generated some additional development of “standards” as reflected by the subsequent publication of Forensic Analysis Standards of Practice by the U.K.-based Guild of Project Controls in 2014. ( Another important addition to the body of expert guides is the ASCE “Standard 67-17 for Schedule Delay” ( This standard was developed by a group of experts and contains significant guidance on performing a forensic schedule delay analysis. It does not identify specific FSA methods.

Recent Methodological Advances

Just as there are more and better definitions of methods, there continues to be advances in the underlying theory relevant to forensic schedule delay analysis. For example, the concept “contemporaneous understanding of criticality” seems to have important, yet not fully understood implications on delay methodology (P. Kelly, Contemporaneous Understanding of Criticality, Transactions 2016, (AACE International). This concept, first reflected in Jon Wickwire’s Construction Scheduling notes that criticality is often related to what the project managers running a project think is critical at any given moment. This has not yet been addressed in the U.S., but a controversy is underway in the United Kingdom concerning whether delay experts should use “blindsight” (standing in the shoes of the contemporaneous project managers) in their analysis or “hindsight” (using all available data, even that not known contemporaneously).

Another area ripe for development is how different delay methods might be integrated into the same analysis. This issue is made more complicated by the generally unrecognized aspect of FSA methods that different methods measure different characteristics of delay: similar to metric and English systems that can both measure distance but do so using different units.

Below is an explanation of the different types of “days” the four major families of FSA methodology measure delay: ( P. Levin, ed., Construction Claims, Chapter 8.)

·       As-Planned vs. As-Built (APAB). This methodology measures delays that actually occur on the day(s) they occur. It does not evaluate the projected delay at the end of the project, but rather measures the delay that has actually accrued at a specific point in the work compared to planned status at the same point in the work.

·       Contemporary Period Analysis (CPA or Windows). This measures a combination of actually accrued delay to the start of the evaluation period, and anticipated delays projected to the end of the project after the start of the evaluation period. The methodology measures actual delay through the start of the evaluation period based on earlier periodic evaluations. It then measures delays projected through the end of the project by comparing the plan at the evaluation period with the projected delay at the end of the evaluation period. Thus it measures two types of delay: actual delays to start of the evaluation period and projected delays thereafter.

·       (Retrospective) Time Impact Analysis (RTIA). This methodology measures delay in two groups also. First it measures “actual” delays at the start of the evaluation period as reflected in the contemporaneous schedule updates. If those updates are inaccurate, then the delay measurement will not be correct. If the contractor has manipulated the go-forward logic and changes in scope to accentuate owner-responsible events, the periodic updates may bear little relevance to the actual needed sequences. Second, the methodology calculates an additional delay at the end of the project through the insertion of a RTIA fragnet into the evaluation period update. This additional delay is based on a mixture of actual activity durations (the TIA fragnet) and planned activity durations (the remaining CPM schedule into which the fragnet is inserted).

·       Collapsed As-Built Analysis (CAB). This methodology measures delay that “actually” occurred by comparing actual dates and events with an expert’s after-the-fact assumption about the should-have-planned sequence of activities. Therefore these days of delay are completely hypothetical because they measure delays against a plan that was never developed or executed.

Thus, it is clear that “combined” delay methods is problematic because the different methods, while each measuring “days,” actually measure different types of delay days.

A final, yet to resolved, issue is why different methods often arrive at different days of delays and allocations of delay responsibility. While partially addressed above, the studies to date seem to indicate that it is the timing of the delay methodology itself that accounts for the differences of delay. (J. Livengood and P. Kelly, Forensic Schedule Analysis Methods: Reconciliation of Different Results, Cost Engineering (January 2015, AACE International) Generally, the as-planned vs. as-built method identifies the delay earliest, and the collapsed as-built method identifies the delay latest. Such timing variances can significantly effect the allocation of delay responsibility.

  Trend Chart of Methods

Trend Chart of Methods

This chart plots the timing of recognition of delays for a model analysis of the four methodological families. Essentially, the APAB methodology identifies the delay occurring on the date it actually occurs, while the RTIA methodology identifies the delay up to two months earlier, the CPA methodology identifies the delay one month earlier and the CAB identifies the delay one month after. (J. Livengood and P. Kelly, 2015)


Experts have made tremendous progress in demystifying and better explaining the process of quantifying delay and allocate responsibility. In support of this, methodological best practices, techniques, and training in CPM schedules and forensic methods are readily available through leading professional organizations such as AACE International, ASCE, and CMAA.

Since 2005, there has been a steady development of cogent methods, explanation of underlying considerations, and training techniques to systematize forensic schedule delay analysis. Work by AACE International, ASCE, The Guild of Project Controls, CMAA, and SCL have all advanced the understanding of forensic schedule-delay analysis.

The result of these two trends—less law and more guidance—have not fully staunched the tide of poorly conceived, voodoo analysis. But there is hope. More arbitrations and mediations led by construction attorneys and construction experts, coupled with a better understanding of delay analysis methods by construction professionals, generally means a continuation of the long-term trend toward better analysis and fairer resolution of delay claims.

John C. Livengood is a senior managing director at Ankura, in Washington, DC. Ankura is the Litigation Advisory Services Sponsor of the ABA Section of Litigation. This article should be not construed as an endorsement by the ABA or ABA Entities.

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