In construction disputes, ‘delay analysis’ is essential for establishing the cause of delay, which in turn determines whether the contractor is entitled to an extension of time and associated costs or whether the employer is justified in imposing liquidated damages. This article enunciates various methods employed in the analysis of construction delays. It provides a detailed overview of the techniques used to identify, quantify and apportion delays among project stakeholders that are critical for the resolution of disputes pertaining to extension of time (EOT) and substantiation of EOT claims.MethodsThe 2nd edition of the Society of Construction Law Delay and Disruption Protocol, 2017, (SCL Protocol) identifies six primary methods for delay analysis, categorised broadly into prospective and retrospective methods as described below:Impacted as-planned analysis: This prospective method involves inserting delay events into a logic-linked baseline programme to assess their theoretical impact on the completion of the project. It assumes the baseline programme to be accurate and unaltered, making it suitable where delays occur early or where the use of this method is stipulated in the contract. However, it overlooks actual progress and subsequent changes on the baseline, thereby limiting its evidentiary strength.Time impact analysis (TIA): This is another prospective method that uses contemporaneously updated programmes that reflect actual progress up to the date of each delay. It provides a more realistic assessment than the impacted as-planned method and is useful for contemporaneous EOT claims. However, it does not consider subsequent developments and relies heavily on the quality of programme updates.Time slice windows analysis: This retrospective method divides the project into time slices, typically at monthly intervals, and evaluates delays in each window using updated programmes. It identifies the evolving critical path and attributes delay based on contemporaneous records. The accuracy of this method depends on the availability of consistent and reliable programme updates.As-planned vs. as-built windows analysis: This retrospective method compares planned and actual progress within a defined window without relying extensively on programming software. It is preferred where baseline or updated programmes are unreliable. The delay causation is established through a reasoned, record-based approach. Its strength lies in flexibility, though it demands clear justification of analytical logic.Longest path analysis: This retrospective method traces the longest path backwards from the actual completion date to reconstruct the as-built critical path. It then compares key dates to the baseline to identify delays and their causes. While it offers insight into actual project delay, it may not fully account for changes in the critical path over time and depends on a detailed as-built programme.Collapsed as-built (but-for) analysis: In this retrospective method, delay events are removed from the as-built programme to provide a hypothesis of what might have happened had they not occurred. It necessitates creating a logic-linked as-built programme, which is rarely available and often needs to be manually developed. Although intuitive, it can oversimplify causation and may not account for concurrent or switching critical paths.PerspectivesIn John Barker Construction Ltd v London Portman Hotels Ltd [1996] 83 BLR 31, it was held that a critical path analysis is a mandatory element of an EOT application, although a calculated assessment with reference to programmes of work would be required as opposed to an impressionistic assessment. In Skanska Construction UK Ltd v Egger (Barony) Ltd [2004] EWHC 1748, Judge Wilcox observed that “the reliability of [the expert’s] sophisticated impact analysis is only as good as the data put in,” thereby highlighting the need for factual robustness to avoid hypothetical conclusions. And in Thomas Barnes & Sons Plc (In Administration) v Blackburn with Darwen Borough Council [2022] EWHC 2598, His Honour Judge Stephen Davies confirmed that strict adherence to the six methods outlined in the SCL Protocol is not required, so long as the analysis produces conclusions that are “sound from a common-sense perspective”.In conclusionThe SCL Protocol provides a framework of recognised methods for analysing delays, each with its strengths and limitations. However, the courts tend to favour methodologies that rely on contemporaneous records and demonstrate a clear causal link between delay events and project completion. Therefore, regardless of the method chosen, parties must maintain an accurate baseline programme, periodic programme updates and comprehensive site records to substantiate EOT claims effectively.About the authors: Ronak Desai is a construction lawyer and heads International Construction Law Offices, Mumbai. Email: rd@constructionlawoffices.com | Assisted by Divya Pahade, Associate, ICLO