Assessing the critical path is paramount to any construction delay claim. Some methods such as the As-Planned versus As-Built in Windows analysis, the Time-Slice analysis, or the Retrospective Longest Path analysis do rely explicitly on a critical path. For other methods such as the Impacted As-Planned analysis, the Time Impact analysis, or the Collapsed As-Built analysis, it may seem that no critical path is involved; yet, behind the scenes, there is! Whatever the method, there is always a critical path.

It is typical to see Experts of opposing sides strongly disagreeing on the critical path, including under the formal duty of independent Expert Witness appointments. This may seem surprising since the duty of an independent Expert is to assist in establishing the truth via the preparation of an objective opinion, as opposed to supporting the case of the party who appointed them. In other words, an Expert Witness’ duty is to the Tribunal.

Hence a recurring question: if they truly act as independent specialists, how can delay Experts disagree? Some will say this is clear evidence of chronic corruption in the Arbitration system? Not so sure! Through this article we will see 5 reasons why opposing construction delay Expert Witnesses may – in good faith – disagree on the critical path.

Data – Information asymmetry

Experts are typically appointed by one of the parties in dispute: the contractor, the employer, or perhaps another stakeholder. Until the entire relevant project information is disclosed across the parties, an Expert is limited to the information they are given. Often, this means to only having access to the formal correspondence exchanged by the parties. Sometimes even worse, a client may filter out sensitive documents they do not whish their Expert to be aware of. Needless to say, these situations can lead to a biased opinion.

An experienced Expert will be familiar with such situations and mitigate this weakness by identifying and confronting the facts presented by the opposing party, often available through claims, reporting, emails, letters or minutes of meetings. The Expert will also cross-check secondary data (monthly reports, schedules, etc) against the primary data they were based on (daily records, photos, notices, etc). Factual evidence may also be available indirectly, through site logs, quality assurance trackers, or even the public domain with satellite photos or news articles. The reliability of the opinions expressed by an Expert can only be achieved via an in-depth review of the project data and detection of these key details which make all the difference.

Occasionally nonetheless, information may be missing, in particular when working for the employer or an investor. These parties rarely get access to primary data. Two construction delay Experts basing their opinion on data sets which differ are prone to reach distinct conclusions.

Budget – Cutting corners with hypotheses

Construction projects gather tremendous quantities of data. The amount of time and the resources available to the Expert are major factors when it comes to establishing a strategy for the processing of this information. The ability to extract the relevant facts is thereby directly related to the budget allocated by the appointing party. This budget may vary depending on various factors, including the strength of the case or what is at stake.

Another factor is regulation. Contracts provide timeframes under which claims must be submitted. Time-bar clauses can be lethal to whom submit their assessment late. Tribunals also set strict calendars which must be complied with. In the recent years, the International Chamber of Commerce (ICC) tends to shorten arbitral calendars in an effort to reduce the cost of a dispute, inherently adding additional pressure on the Experts. One of the extreme forms of this trend being the ICC Expedited Procedure provisions.

When there is no time, shortcuts need to be taken. This may materialise through various hypotheses, taken in order to reduce the volume of work which would have otherwise been required. Two construction delay experts basing their opinion on different hypotheses may reach differing conclusions.

Opinion – Experience matters

Experts provide an opinion, based on their experience and knowledge of industry good practice. Their duty is to help the parties, and most importantly judges and arbitrators, to understand a set of technical matters. This help is provided through the establishing of a composition of opinions and conclusions as close as possible to the Truth.

Although a delay Expert has many tools at their disposal to narrow their spectrum of subjectivity, it would be deceitfully to pretend holding the very Truth. For example, an experienced Expert may rely upon an objective methodology in order to stay as neutral as possible, but yet the choice of this method would remain subjective.

Independent Experts provide an opinion, to the best of their ability. Under the same circumstances, different delay Experts with different experience are prone to making differing methodological choices and assumptions.

Project – Critical path target

The critical path is often pictured as one unique and tangible element of a construction project. In reality, it is the complete opposite. A critical path is merely a tool in order to measure the prevalence of project activities amongst others, for a given target and a given set of conditions. When the target or the conditions change, the path does too.

The SCL Delay and Disruption Protocol defines the critical path as “The longest sequence of activities through a project network from start to finish, the sum of whose durations determines the overall project duration”. Another definition is that of the Project Management Institute PMBOK which says it is the “sequence of activities that represents the longest path through a project, which determines the shortest possible duration”. The critical path is such a useful tool because a delay to any activity along this critical path – a critical activity – is directly related to delaying the project completion date.

It is crucial to understand that a critical path targets a project. This project may be The Project object of the full scope of a contract, but it may be different. For example, a contract may associate liquidated damages to intermediate completion milestones.

Some circumstances specific to a given dispute may require establishing what delayed the occurrence of an event, such as first power to a grid. On a case a few years ago, I was asked to identify the causes of the delays to the demobilisation of an expensive piece of rented equipment: I therefore looked at the critical path to the demobilisation, which had nothing to do with the overall project critical path. Depending on what scope is being evaluated, the definition of ‘The Project’ may shift to ‘a project’, or several sub-projects, which directly affects which critical path is being looked at.

Delay Experts may calculate the critical path to projects which could look the same, but are actually defined with subtle yet consequential differences. For example, the critical path to the project overall completion may differ from that of the project substantial completion. Activities such as landscaping and site cleaning may strongly affect the critical path; yet, are they essential?

Ultimately, an Expert answers the questions set forth in their instructions. The scope object of the analysis usually originate from these instructions. If the scope cannot be unambiguously deducted from these instructions, an experienced Expert should clear any doubts by plainly identifying this scope in their report.

Taxonomy – Temporal perspective

Once the project object of a critical path analysis has been defined, one has yet to define the temporal perspective: prospective, retrospective, contemporaneous. These types of perspective have been defined by the industry because they answer different questions, respectively: what was the original plan? what happened in the end? What was the intent at some point during the course of the works?

A prospective critical path refers to a forecast, an intent under a hypothetical set of assumptions. It often relates to the baseline programme, usually attached to the contract or due within 60 to 90 days from the notice to proceed. This critical path indicates what is the sequence of activities which we can expect will dominate the project completion date, if everything unfolds according to the plan. This path is available from the beginning of the project. It is sometimes referred to as the as-planned or baseline critical path.

A retrospective critical path refers to a photo-finish, a recompilation of what actually happened. It often relates to the as-built programme, usually visible in the last progress reports, issued at project completion. This critical path indicates what was the sequence of activities which, in the events, dominated the project completion date. This path is only available at the very end of the project. It is often referred to as the as-built critical path, and sometimes to the true or actual critical path.[1]

A contemporaneous critical path refers to the critical path a project manager would establish on their weekly or monthly routine. It establishes what concerned the stakeholders at a given point in time (the data date) and how they adjusted the remaining schedule accordingly. This path accounts for all the experience learned from the project up to the data date. Ideally, it would include activity remaining durations based on the rates of productivity experienced on site, actual delays occurred up to the data date, known future delays, realistic mitigation plans such as re-sequencing, etc.

An actual critical path, or true critical path,[2] refers to the sequence of activities which, at the time they were being carried out, were perceived as dominating the project completion date. Figuratively, it is the timeline of these activities which prevented the project director to sleep at night. Establishing this path consists in merging a set of contemporaneous critical paths, then to only keep the sequence of these activities which were identified as critical at the time they were progressing. This path unfolds as the project develops. Actual critical paths and their role in delay analysis are often misunderstood; they will be the object of a dedicated article in the future.

Depending on the chosen type, critical paths often dramatically differ. The choice will largely depend on the instructions the expert is answering. This is another and one of the most common reason for delay expert opinions to diverge.

[1] Note the term actual can be misleading as the SCL Delay and Disruption Protocol defines the actual critical path as the path when the assessment is contemporaneous.

[2] Note the term true can be misleading as it may also refer to a retrospective critical path; I recommend the term actual critical path, which is consistent with the definition proposed by the SCL Delay and Disruption Protocol.

In this article:
It is not uncommon to see independent Experts of opposing sides strongly disagreeing on the critical path. Through this article we will see 5 reasons why opposing construction delay Experts may, in good faith, disagree on the critical path.
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