Disruption is one of the most difficult heads of claim in construction disputes. Unlike delay, which can usually be measured against a programme, disruption is the loss of productivity suffered by the contractor in carrying out the works in less efficient conditions than those it was entitled to expect. A disruption claim does not necessarily depend on the works being completed late — disruption can arise even where the contractor completes on time, by virtue of the additional resources required to do so.
The conceptual distinction between delay and disruption is fundamental. Delay is the additional time taken to complete the works as a result of an event affecting the critical path. Disruption is the additional cost (or reduced output) incurred as a result of working in conditions that prevent the planned productivity from being achieved. The two can occur together — disruption may cause delay, and delay may cause disruption — but they are distinct heads of claim and are quantified differently.
The recognised methodologies for quantifying disruption fall into two broad categories: productivity-based methods (which compare actual productivity with a benchmark of planned or undisrupted productivity) and cost-based methods (which compare actual cost with the cost that would have been incurred in undisrupted conditions). The SCL Delay and Disruption Protocol identifies a number of specific methods within each category, including the measured mile, earned value analysis, comparison studies, work or trade sampling, and various formulaic approaches.
The measured mile method is widely regarded as the most robust where the project records permit its application. It compares the contractor's productivity during a period when the works were not disrupted (the 'measured mile') with productivity during the disrupted period, and attributes the difference to the alleged disruption events. The strength of the method lies in its grounding in the contractor's actual performance on the same project, but it depends on the existence of an undisrupted period and on records of sufficient granularity to support the comparison.
Earned value analysis compares the value of work actually performed during a given period with the value that should have been performed according to the planned programme and budget. Where the actual value is less than the planned value, the difference may be attributable to disruption — but it may equally be attributable to other causes such as contractor inefficiency, sequencing issues or design changes. Careful analysis is required to isolate the disruption component.
The least robust methodologies are the so-called 'global claims' or 'total cost' approaches, which simply compare the total actual cost of the project with the total tendered cost and attribute the difference to disruption. Tribunals are generally suspicious of global claims because they assume that the entire cost overrun is the responsibility of the employer, and they require the claimant to disprove rather than prove causation. Global claims should be avoided where any more rigorous methodology is available.
Our quantum and disruption experts at Construction Expert Witness have substantial experience of preparing and defending disruption claims on Middle Eastern projects. We work from contemporaneous records wherever possible, apply the most robust methodology that the records will support, and present the analysis in a transparent and well-evidenced form.