Sustainable Leisure-Oriented Bus Use in a Motorizing City: Car Ownership, Perceived Barriers, and Evidence from Harbin, China

Promoting public transport use in leisure contexts is important for extending sustainable mobility policy beyond commuting. However, the role of car ownership in realized leisure-oriented bus use remains insufficiently understood, especially among residents who already have bus use experience. This study examines how car ownership and perceived public transport barriers are associated with leisure-oriented bus use intensity in Harbin, China. Based on 688 questionnaire responses from residents with leisure-oriented bus use experience, this study combines group-difference tests, threshold-based binary logit models, and XGBoost-SHAP exploratory analysis. The results show that, within this bus user sample, car owners and non-car owners do not differ significantly in realized leisure-oriented bus use intensity. However, car owners report significantly higher perceived spatial constraints, temporal constraints, bus use resistance, and overall perceived barriers than non-car owners. The binary logit models did not provide robust statistical evidence that car ownership-related heterogeneity differed across bus use intensity thresholds, although the interaction results should be interpreted as suggestive rather than conclusive. Because the XGBoost model showed limited discriminatory performance, the SHAP results are retained only as exploratory and descriptive information rather than confirmatory evidence. The findings suggest that sustainable leisure mobility policies should distinguish between car owners and non-car owners among existing bus users, while avoiding generalization to all urban residents or complete non users.