How portfolio screening differs from site-level investigation

Site-level investigation asks: what is happening at this asset, and what should we do about it? Portfolio screening asks a different question: across these thousands of assets, where should we look first? The methods, outputs, and standards of evidence differ accordingly.

A screening produces indicators — movement statistics per location, comparisons against local context, flags and rankings. It deliberately trades depth for consistency and coverage. A site investigation produces interpretation: a careful reading of the full time series, surrounding movement field, data quality, and site context, framed for a specific decision.

Screening results should never be read as verdicts on individual assets. A flagged location means the data justify a closer look, not that a problem exists; an unflagged one means no signal was detected under screening assumptions, not that the site is certified stable. Organisations that respect this distinction get the full value of both tools: screening concentrates scarce inspection and analysis budgets, and site-level work is then spent where evidence suggests it will matter.

In practice the workflow layers naturally: screen the whole portfolio on public radar archives; review the ranked output with whoever holds asset knowledge; commission focused site assessments on the shortlist; and, where warranted, move individual sites into ongoing monitoring. Each step is priced and scoped on its own, so the programme scales with the evidence.