Geospatial Assessment of Metro-Based Multimodal Alternatives to Ride-Hailing and Associated Health Co-Benefits: A Utility-Based Counterfactual Framework

Ride-hailing provides convenient door-to-door mobility but may also reduce public transport use and transport-related physical activity. This study develops a spatially explicit utility-based counterfactual framework to compare observed ride-hailing trips with metro-based multimodal alternatives and assess potential health implications. Using over twenty million georeferenced ride-hailing orders recorded in Nanjing, China, in 2025, we generated complete multimodal alternatives by integrating origin–destination locations with metro and street-network data. The two travel options were compared in terms of generalized utility, travel impedance, spatiotemporal patterns, and physical activity. The results show that, under the baseline utility specification, 13.31% of ride-hailing orders were identified as having a comparatively competitive metro-based multimodal alternative. These orders were concentrated during weekday commuting peaks, around metro stations and corridors, and along inward flows toward central urban areas. Under a counterfactual scenario in which these identified ride-hailing orders were replaced by multimodal travel, transport-related physical activity was estimated to increase by 116.7 kcal per trip, resulting in remarkable gross health benefits when extrapolated to the citywide population. Overall, the framework provides a geospatial screening approach for identifying where and when multimodal alternatives may be competitive with ride-hailing, and highlights the importance of reducing access, egress, and transfer disutilities in improving multimodal competitiveness and associated health co-benefits.