Hearing the Silence: Early Warning Signals in Megaproject Portfolios

Early warning signals are well developed for individual projects but absent at the portfolio level, where uncertainties are routinely flagged yet rarely linked to corrective control, a signal without response pathology. Through a 2-year embedded case study of a megaproject portfolio, this article extends early warning signal theory from project to portfolio, specifying three requirements that distinguish a portfolio signal: portfolio-native, mechanism traceable, and time-lagged to the horizon of portfolio-level levers. Six content-validated leading indicators operationalize the governance drivers of portfolio success; one indicator—proportion ahead of required date (PARD)—is operationally tested, bridging sensing capacity and corrective action in megaproject portfolios.