Big data sources have been used extensively to analyze people’s travel patterns. This project breaks new ground by using big data on travel patterns to identify the incidence and severity of travel problems – defined here as any difficulty a person may experience in reaching desired destinations. Relying on a large-scale app-based mobility survey, data will be extracted on individual’s trip rates, travel horizons, trip speeds, and more, with the aim to detect individuals particularly likely to experience severe travel problems.