Disruption (vs Delay)

Delay and disruption are commonly grouped but are conceptually distinct. Delay is the extension of the project's Completion Date (or a Key Date) beyond what was planned, driven by events on the critical path. Disruption is the loss of productivity on activities that may not have been on the critical path — the work takes longer, costs more, and involves more resource than planned, even if the overall project still finishes on time.

Disruption typically arises from events like interference with the Contractor's intended sequencing, poor site access, late design information, or excessive instructions. The financial impact manifests as lower productivity rates — an activity that was planned at 100m/day achieved 60m/day because of interference — rather than as straightforward delay days. Recovering disruption costs requires proof of the productivity loss, the cause, and the financial consequence: a different and generally more difficult evidential task than proving critical path delay.

The SCL Delay and Disruption Protocol treats disruption explicitly and describes several analytical methods, including measured mile analysis (comparing productive periods against disrupted periods on the same project), industry productivity benchmarks, and modified total cost methods. Each has strengths and weaknesses, and the choice depends on what evidence the Contractor can produce. Projects where productivity was tracked contemporaneously have stronger disruption analysis available; projects where productivity was not tracked find disruption claims much harder to substantiate.