The interconnected systems that carry millions of people through modern cities carry within them a hidden fragility: when one thread breaks, the whole web can tremble. A study published in Nature traces the precise mechanics of how disruptions cascade across multi-modal transit networks—subways feeding into buses, buses into trains—revealing that the very integration which makes urban mobility powerful also makes it vulnerable. The research offers city planners not a reason for despair, but a map: identifying where resilience can be built, where capacity must be strengthened, and how the rhyth