Prospective vs retrospective delay analysis: new TCC commentary Matthew Taylor A TCC decision last week has considered the difference between prospective and retrospective approaches to delay analysis. The decision finds that the two approaches will not necessarily lead to the same answer (contrary to suggestions made in a previous TCC decision). The decision may also provide support for the use of prospective approaches in the assessment of extension of time claims – a point which is likely to be controversial. Introduction Infrastructure, construction and energy disputes commonly involve issues which require delay to be assessed. Delay experts are often engaged by parties to prepare reports analysing the delays on a project. A range of delay analysis methodologies exist and there is broad consensus that no single methodology is to be preferred in all cases. The choice of methodology has both legal and factual aspects: it must meet the requirements of the legal issue under consideration, be consistent with the requirements of the contract and must also be appropriate to the evidence available and the factual characteristics of the project in question. A broad distinction between delay analysis methodologies can be made between those which are “prospective” and those which are “retrospective”. Prospective methodologies (such as “time impact” or “impacted asplanned” analyses) involve assessing criticality and delay contemporaneously at the time the events in question occurred. By contrast, retrospective methodologies take into account subsequent events and attempt to establish whether the events in question actually caused delay to completion when the progress of the work as a whole is considered.
Do both lead to the same result? In 2012, the TCC gave judgment in the wellknown Walter Lilly case. In considering claims for extension of time, the court was required to consider the appropriateness of what was said to be a prospective methodology. The court noted that: “The debate about the ‘prospective’ or ‘retrospective’ approach to delay analysis was also sterile because both delay experts accepted that, if each approach was done correctly, they should produce the same result.” This statement has proved to be controversial, with commentators pointing out that a retrospective approach, by definition, takes into account matters which a prospective approach does not. The court’s comments in this regard may perhaps be explained by the unusual circumstances of the Walter Lilly case and the fact that the prospective methodology adopted by the Claimant’s delay expert was “reality checked” against subsequent events. Is one to be preferred over the other? The circumstances in which the law might prefer a prospective approach over a retrospective approach are unsettled. Insofar as extensions of time are concerned, the original version of the SCL Delay and Disruption