Disruption is the disturbance or hindrance of the contractor's intended method of working, resulting in loss of productivity. Unlike delay claims (which focus on the time for completion), disruption claims focus on the cost of inefficiency — typically additional labour and plant hours expended over and above what was planned. Core Principle 18 of the SCL Delay and Disruption Protocol provides detailed guidance on the analysis and presentation of disruption claims, and the role of the disruption expert witness.
Disruption can occur even where there is no delay to the completion date. A contractor may complete on time but at significantly increased cost because employer-caused interruptions, out-of-sequence working, design changes, late information or restricted access have eroded productivity. These additional costs are recoverable in principle, but require careful analysis to substantiate.
The SCL Protocol identifies several recognised methods of disruption analysis. Productivity-based methods include the measured mile (which compares productivity in undisrupted periods with productivity in disrupted periods on the same project), earned value analysis (which compares budgeted hours with actual hours by reference to physical progress), and industry studies (which apply published productivity factors to the disrupted activities).
Cost-based methods, by contrast, calculate the disruption cost by reference to the contractor's actual labour and plant cost, less the planned cost, with appropriate adjustments. Cost-based methods are generally less reliable than productivity-based methods because they capture all causes of additional cost, not only those attributable to employer-risk events.
A disruption expert witness will typically prefer productivity-based methods where the records permit, and will use the measured mile as the benchmark wherever possible. The credibility of the analysis depends critically on the quality of contemporaneous productivity records — daily labour returns, plant utilisation logs, and progress measurement records linked to specific work areas.
In Middle Eastern construction, where MEP fit-out, façade and finishing trades are particularly susceptible to disruption from interface delays and design changes, disruption claims are an increasingly important category of dispute. Engaging a specialist disruption expert witness early in the project — and certainly as soon as a dispute is contemplated — is essential to ensure that the records, the analysis and the presentation are aligned.